Dolphin Communication Project

Dolphin Communication Project

The Dolphin Gazette 20.4
13 December 2019

The Dolphin Gazette 20.4

Field updates, holiday specials & more!

The latest issue of the Dolphin Gazette is now available! The fall issue of The Dolphin Gazette is always a fun one to write. Kathleen has returned from Roatan, holiday specials are in the air and collaborators share news! This issue is no exception. We hope you enjoy reading about upcoming field opportunities, our t-shirt fundraiser, holiday bundles, new papers....and, we hope you'll pass the Gazette on to a friend!

Click here to download a PDF of the gazette!

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E-kit delay notice
13 December 2019

E-kit delay notice

Due to upcoming field schedules and access to email, e-kit adoption orders received between 21 - 31 October may not be filled until 1 November. Of course, if we are able to fill kits more quickly, we certainly will! Thanks for your support!

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Spotted Dolphins of the Bahamas
13 December 2019

Spotted Dolphins of the Bahamas

Check out this video from our friends at Bahamas Marine Mammal Research Organization and Loggerhead Productions. It includes some great information about the spotted dolphins in The Bahamas – and DCP’s own Kel Sweeting makes a cameo with the Bimini dolphins!

Spotted Dolphins of the Bahamas from Conch Salad TV on Vimeo.

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DCP's 2015 Bimini Video
13 December 2019

DCP's 2015 Bimini Video

DCP is pleased to share with you our breathtaking new video showcasing our research at Bimini, The Bahamas. Produced by Terramar Productions, our 2015 Bimini Video introduces you to the dolphins around Bimini, as well as the scientists studying them. Kathleen and Kel both make an appearance, as well as a number of our colleagues and collaborators (and students) and of course our Adopt-a-Wild Dolphins!  DCP welcomes a number of secondary level and college level students from a variety of schools to Bimini each year. Want to join us on Bimini one day? Click here to learn more

 

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Dolphin Ringtones!
13 December 2019

Dolphin Ringtones!

Hey there adopt-a-dolphin folks!

Looking for your dolphin's ringtone? You've come to the right place! Click on one of the below links and enter the password you received in your adoption kit. It's at the bottom of the page with your dolphin's biography. If you run into any trouble, just  can send us an email.

General Bimini dolphin whistle (click here if you can't find your dolphin's name below) (password required)

Freckles (password required)

Tina (password required)

Noodle (password required)

 

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Adopt-a-wild-dolphin Holiday Bundle 2019
13 December 2019

Adopt-a-wild-dolphin Holiday Bundle 2019

Adopt-a-wild-dolphin Holiday Bundle 2019!

It's time to put a little more dolphin in your life by purchasing a dolphin-themed gift that will also help support dolphin science and conservation. The Dolphin Communication Project is offering a very special, limited edition Adopt-A-Wild-Dolphin Holiday Bundle this holiday season. For just $50 you can adopt one of five dolphins we have handed picked for this offer from our adopt-a-wild-dolphin lineup and you'll receive a dolphin bracelet from Wanderer Bracelets. The dolphins: Tina, Weiloo, Vee, Split Jaw, and Paul. You'll get all the goodies in our regular adoption kit (see below for details), and a beautiful dolphin bracelet desinged by Wanderer Bracelets! This bundle offer is only good until December 31st, 2019. DCP cannot guarantee arrival before Christmas (especially for international orders), so order early to avoid disappointment! Bracelet supplies are limited, so this offer is only valid while supplies last. 

This Holiday Bundle is just $50 - that's a 25% savings over purchasing an Adoption Kit & Wanderer Bracelet separately. And, it includes standard shipping within the US! (Expedited & international shipping are options available.)

To take advantage of this special offer read about Tina, Weiloo, Vee, Split Jaw, and Paul(their bios are below), decide on your favorite, and then fill out our order form. 

Pick your dolphin!
Name on Adoption Certificate

adopt a dolphin Tina
 

 Tina (#14): Tina is one of everyone’s favorite dolphins as she is easy to ID and very playful- with passengers and with other dolphins! First seen in 2002, she is sometimes seen in the company of Leslie (#80) and Nemo (#76). Recognized by the large spot and vertical scars on the left side of her peduncle, she often very curious about our camera but occasionally completely oblivious! Tina was named for Pete, Amparo, and Kyle Furey by Jessica Wood in November 2004.


Weiloo (ID#110): Weiloo is an older, juvenile, female Atlantic spotted dolphin. DCP has been observing her off the coast of Bimini, The Bahamas, since 2015, when she was already independent from her mom..

 

adopt a dolphin Split Jaw
Split Jaw (#22): Split Jaw was first seen in May of 2001 when the impressive wound on his jaw (the inspiration for his name) was pretty fresh. His jaw injury is now very well healed and Split Jaw is developing lot of spots! Split Jaw is extremely social!

 


Vee (ID#101) - Vee, a female Atlantic spotted dolphin, has been observed by DCP since 2012. We monitor her spot development carefully – so far, she has no nicks or scars! Because of this, researchers rely on her spot pattern to recognize her, year after year. Thankfully, she seems fairly interested in the boat and our cameras, which allows us to document her new spot development and associations over time.

Paul (#99)  has been observed off Bimini since 2011, the first summer after he was born. In the early years, when he was always by his mom (Leslie, #80)’s side, the pair spent much of their time with Lil’ Jess (#35) and her calf. Paul is easily recognized by the double notch in his peduncle. Paul Alexander Landis, aka Paul or PAL, was named in 2015 by Carl & Sylvia Landis, in memory of their son, Paul Alexander Landis, who loved the ocean.

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Know which dolphin is your favorite? Time to order! Just fill out the below form and we'll get your Holiday Bundle to you ASAP!

Pick your dolphin!
Name on Adoption Certificate

 

What's in your Adoption Kit?

Adoption Kit

 

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Thank you

Thank you for your order!

Your order has been received and is being processed.

If you ordered an electronic version of our adoption kit, we will email you within a few days with links to your electronic files.

If you ordered a hardcopy version of our adoption kit, please note the following: for orders submitted using Economy shipping, you should expect your order to arrive in 2 to 3 weeks, a USPS tracking number will be sent to you via email. Rush Expedited orders will be processed within 1-2 business days and shipped via USPS Priority Mail. The USPS tracking number will be sent to you via email for confirmation.

If you have any questions about your order, please email DCP at the following address: info {at} dcpmail {dot} org

We truly appreciate your order. Please know that your purchase helps fund our research and education efforts, and will help fulfill our mission to promote the scientific study of dolphins and inspire their conservation.

Thanks! DCP

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Ah! The Dolphin Gazette is here!
13 December 2019

Ah! The Dolphin Gazette is here!

Issue 18.4 of the Dolphin Gazette is a big news issue!

From a new mailing address to a revamped website, this issue of The Dolphin Gazette is a busy one! Kathleen fills us in on her recent trip to RIMS, holiday specials provide a do-good way to shop, Kel checks in from Bimini and more! Click here to download.

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Bimini Dolphins Photobook
13 December 2019

Bimini Dolphins Photobook

DCP is proud to announce the release of our official Bimini Dolphins Photobook! This 8x6  soft-cover photobook has been lovingly put together by our research team, and features photos of all of the 20+ wild Atlantic spotted dolphins that form our Adopt-A-Wild-Dolphin catalog. The book contains amazing images and short biographies of our dolphin friends, including Milo, Tim, Tina, Lone Star and all the rest of the gang. At just $30 for the album (which includes shipping) it's a great deal AND you'll have the satisfaction of knowing that all the money raised from the sale of our Bimini Dolphins Photobook will go toward DCP's research and education efforts. Check out images below of some of the DCP gang enjoying the book. Beagles love it too!

 Get your Bimini Dolphins Photobook today!


*Free standard shipping!

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December Dolphin Deal
13 December 2019

December Dolphin Deal

If you adopt a dolphin from DCP's Adopt-A-Wild-Dolphin program or donate $25 or more between December 2nd and New Year's Day, you'll receive a link to view our brand new adopt-a-wild-dolphin slideshow (in .m4v format)!

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Join #TeamDolphin this holiday season!
13 December 2019

Join #TeamDolphin this holiday season!

Get the official #TeamDolphin t-shirt!

Check out our official #TeamDolphin t-shirt. We’ve launched a holiday t-shirt fundraising campaign featuring a trendy version of DCP’s dolphin logo, together with our official #TeamDolphin hashtag. The shirts are available from Bonfirefunds.com - a company that helps non-profits (like us!) raise funds. If we can pre-order 50 t-shirts by the end of the campaign, Bonfirefunds will print and ship our #TeamDolphin t-shirts to all our awesome supporters who put in an order, and send us the funds raised during the campaign. 100% of the proceeds will go towards funding our non-profit research and education efforts.

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A DRT Summary

Our trip home was uneventful and followed by jet lag!

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Our Last Day in Tokyo

Our last day brought is to the East Garden of the Imperial Palace on a guided tour followed by a visit to the Diet (Government) Building for another tour.

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Sunday, Sunday

We visited Odaiba and the Panasonic Center (techonology), a food court, the Asakusa Kannan Temple, and then finished the day with Karaoke.

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Day Two in Tokyo

We visited the Edo Museum (and outside of the Sumo museum), McDonald’s, Shinjuku Station (largest and busiest in the world), Tokyo Government Building, Meiji Shrine, and had Sukiyake for dinner.

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Our First Full Day in Tokyo

Our day ranged along the following: Tsukiji, Hamarikyu Gardens, Starbucks, A Tea Ceremony, a Japanese Mall Food Court and Tokyo Tower

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Hiking to Nango

The “Shi no ki” is the biggest tree in Japan and the largest is on Mikura (13 m in circumference)

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DRT Dolphin Trip!

A morning wet suit and mask, fin, snorkel fitting before we arrived to the port for our trips.

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The Dolphin Species Song
13 December 2019

The Dolphin Species Song

 
In this week’s episode, we present The Dolphin Species Song! The Dolphin Species Song (produced by the Dolphin Communication Project) lists all of the known dolphin species - set to the tune of Gilbert and Sullivan's Modern Major General.  Watch the video version:
 
 
Lyrics:

Spinner, spotted, southern right whale northern right whale bottlenose
Hector's, Risso's, Fraser's, Striped, Indo-pacific bottlenose
The humpback comes in maybe 3 or 4 or even 5 species
But there are many more than these so pay attention please

La Plata, Ganges, Indus, Amazon, and the Tucuxi too
These are the dolphins that live in fresh water rivers yes it's true
The Baiji once was on the list but now it's gone it don't exist
pollution made it disappear it will be very sorely missed

Beluga's not a dolphin but I thought I'd name it anyway
White beaked dolphins have a white beak which is why there' named that way
Commerson he named a dolphin Heaviside he named one too
if you're a famous scientist those are the things they let you do

the long finned pilot whale is not a whale no it's a dolphin too
the short finned pilot whale has slightly shorter fins oh yes it's true
The melon headed whale does not have melons for a head and
it's a dolphin not a whale I hope I'm not confusing you

they call the orca killer whale though it's a dolphin like the rest
there's clymene, rough-toothed, hourglass, and dusky I like them the best
The Irrawaddy dolphin swims in rivers and the ocean
it's a quite uncommon notion to this fact I can attest

Long and short beaked common dolphin Hector's, Peal's, and Black oh my
Pacific and Atlantic white sided and striped and Maui's kind
There's false and pygmy killer whale Australian snubfin's the new guy
and now I think I've named them all so next time I think you should try

 

 

 

 

 

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Dolphin communication, cookie cutter sharks, dolphin news (Episode 10)
13 December 2019

Dolphin communication, cookie cutter sharks, dolphin news (Episode 10)

In this week’s episode, we will review breaking Dolphin News from around the world, focus our Science Spotlight on dolphin communication, and in our Kids’ Science Quickie, we’ll discuss cookie cutter sharks.

 

DolphinPod News


Men convicted of harassing a dolphin

The two British men accused of harassing Dave, a friendly dolphin often sighted off the coast of Kent, have been convicted by a British court. The two men reportedly swam with Dave early in the morning while returning home from an evening of drinking. They continued to swim with Dave even after authorities arrived and told tem to leave the water. Video of the incident shows Dave behaving aggressively toward the men, and showing signs of distress. Expert marine mammal witnesses testified that Dave was likely traumatized by the event. The two men were convicted of intentionally or recklessly disturbing a wild animal, and each were fined 350 pounds and sentenced to 120 hours of community service.


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 Science Spotlight


 

Listen to the science spotlight on dolphin communication:

Introduction to Communication

Before we discuss the many ways in which dolphins communicate, it is first important to get straight exactly what communication is. Quite simply, communication is the transmission of information .  This is a broad definition that covers all of the many ways that the word ‘communication’ is used, not just in terms of living organisms. Modern technology is based on communication protocols that allow printers to communicate with computers, web browsers to communicate with web servers, GPS systems to communicate with satellites, etc. Each of these systems relies on a structured communication protocol that allows these computer devices to receive and understand instructions. 

Animals too rely on structured communication systems to help transmit information. In fact, the ability to communicate information is ubiquitous in the animal kingdom : all life on this planet is able to communicate, both with other individuals of the same species, and with individuals of different species.  The methods used for communication are varied and complicated, and are not limited to vocalizations. Ants for example share large amounts of information with other members of the colony through chemical trails and pheromones. Bees are known to communicate complicated information about the location of flower patches by engaging in an intricate ‘dance’ that lets other bees know the distance and direction of tasty nectar-rich flowers. (Bee Audio)

The bee waggle dance: 

 

But communication need not necessarily always be thought of in these complex terms – sometimes messages are much simpler. A large bull moose, for example, grows enormous antlers that convey a relatively straight forward message: I’m big and strong – don’t mess with me! Communicating these kinds of simple messages is not restricted to the animal kingdom however. Flowers too communicate –many species of flowers demonstrate this ability when we take a special photograph using ultraviolet photography equipment. What may look like a beautiful solid-color yellow primrose or dandelion to the naked eye looks completely different when viewed in ultraviolet lighting conditions:  intricate patterns and stripes lead into the center of the flower where the pollen is located.  These patters evolved specifically to attract the attention of animals that see ultraviolet light – chiefly bees. (Bee Audio) In fact, much of a flower’s structure is designed to communicate information specifically with insects.  (Bee Audio) OK, enough with the bees!

A flower photographed in ultraviolet light: 

ultraviolet flower

Complex multi-cellular organisms like bees (Bee Audio) hey!, flowers and humans rely on communication systems at the cellular level to function properly. Communication occurs between your brain and your muscles through tiny electrical currents flowing through your nerves. Cells in your body communicate information with other cells by releasing and receiving various proteins, and a breakdown in these communication channels leads to devastating problems like cancer and diabetes.  
In fact, the ability to communicate is so commonplace for living beings that scientists are convinced that if alien life does exist, it too will have the ability to communicate. What’s more, scientists think that intelligent life, if there is any in the universe, will probably have developed mass communication abilities similar to that of humans, likely involving radio waves. The governments of the world are so sure of this idea that they have funded the multimillion dollar SETI project (Search for Extra Terrestrial Intelligence), which has spent 24 hours a day for the past few decades listening to the background noise of space with giant radiotelescopes hoping to hear something that resembles a communication signal from alien life forms. (Sci-Fi noise) So far, this is all they’ve heard. (Static)

 Carl Sagan explains SETI:

 

LanguageDarwin the Dolphin
So what then is language? In a previous episode of The Dolphin Pod , we discussed what the difference is between language and communication, so I won’t go into detail here. In brief, human language is a system of combining small meaningful elements into larger elements, forming phonemes, words and sentences that allow humans to convey infinitely complex amounts of information. After many years of study, scientists now think that some animals may possess small parts of this system within their own communication systems that allow them to generate some basic forms of human language-like communication, but nearly everyone agrees that only humans are able to learn and use language to the complicated extent that we know as ‘language’. The idea that we can plop a translation device onto a dolphin and turn their whistles into something akin to human language – like Darwin the Dolphin from Sea Quest  - is science fiction (Darwin Audio)

 

Animal Communication
Instead of human language, animals possess their own communication systems that allow them to transmit information. Scientists often define animal communication as follows: Bradbury & Vehrencamp (1998) provided this definition: “communication involves the provision of information (via a signal) by a sender to a receiver, and subsequent use of this information by the receiver in deciding how or whether to respond. As we have already discussed, these signals occur in many forms: a moose’s antlers signal that it is big and dangerous, changing the behavior of smaller moose – possibly discouraging them from entering into a fight. Bees transmit signals that tell other bees where flower patches are, influencing their behavior by encouraging them to fly out and have a look. These signals occur in different channels: for example, visual signals, auditory signals, chemical signals, etc. Scientists sometimes call these ‘modes’ of communication.

Dolphins produce a vast number of signals in a variety of modes which we will discuss here. The different channels or modes include: vocal signals, non-vocal auditory signals, visual signals and tactile signals. It is unlikely that dolphins transmit olfactory signals – those are signals that involve the sense of smell. Dolphins’ sense of smell is likely extremely restricted or entirely vanished, and their ability to smell underwater is probably non-existent. (Listen, Do you Smell Something ) There is a possibility that they may use taste to some extent – for example, dolphins may release chemicals into the water (e.g., from feces) that transmit information about arousal levels or reproductive status. But scientists aren’t too sure if this is the case.

Dolphin Communication - Vocal Cues
So let’s start by covering the most obvious form of communication that dolphins use: vocal signals. Dolphins produce two kinds of vocal signals: pure tones and pulsed sounds. Pure tones can take the form of whistles (Whistle), chirps (Chirp), screams (Wilhelm Scream) sorry – screams (Scream) and other continuous sounds that you are likely familiar with.
Scientists refer to these as ‘frequently modulated sounds’, which means that the pitch of the sound changes with time – rising and falling.

Scientist have leaned that dolphins are amazing vocal mimics – able to reproduce manmade whistle structures with precise accuracy. Dolphins produce whistles during social situations, when separated from friends, when excited, when happy and when panicked. Different whistles are produced in different situations, and scientists have been attempting to catalog and categorize whistles from study populations for some time. This is an extremely complicated process, and much has been written about how various species develop and use whistle communication. The whistles and other vocal calls of orca have received considerable attention, and scientists have discovered that family groups appear to reliably produce distinct categories of whistles and other calls that are stable across time, and that appear to be taught to new members of the group. These calls are so distinct that researchers are able to distinguish different family groups just by listening to their calls.
Here is an example of Orca Call Type N47 used almost exclusively by the A30 Matriline. (Orca Calls Here)

 

Scientists studying bottlenose dolphins have proposed the idea that each individual dolphin produces its own ‘signature whistle’ – a stable unique whistle structure that a dolphin develops during the first year of its life. Dolphins appear to be able to produce their own signature whistle quite reliably, but also the signature whistle of their friends.  Isolated or lost dolphins appear to frantically produce signature whistles, apparently calling out to their friends. The jury is still out on the exact nature of the signature whistle however – some scientists believe that the whistles may not be all that stable – changing over time throughout a dolphin’s life. And it may be, like the orca, that these signature whistles are simply variations of shared whistles within a group. Regardless of the details, it is clear that whistles form an important basis from which much acoustic communication takes place between individuals. It should be noted however that there are a number of dolphin species which do not in fact produce any whistles whatsoever. These species are thought to communicate vocally using only pulsed sounds 

Unlike whistles, pulsed sounds are brief sounds (called clicks) that occur in rapid succession at regular intervals. A series of clicks together is called a ‘click train’. Usually scientists classify these as either echolocation clicks, or ‘bursts pulses’. Echolocation clicks are used for sonar purposes (check out our episode on echolocation for more information ), and generally a dolphin will make a click and then wait for the echoes from that click to return before producing the next click. Echolocation is not a form of communication, but rather a method of ‘seeing’ the world through sound. By listening to the information coming back in the click echoes, dolphins can get a mental image of objects in their environment.

Burst pulses occur when dolphins release clicks so rapidly that it is not believe that they are able to gain any sonar information from the returning click echoes. Clicks can be released as high as 200 a second and still likely yield information for echolocation – but clicks released over that rate, and extending as rapidly as 2000 clicks per second – are thought to be communication signals, not echolocation signals. Dolphins of many species release bursts pulses when they are excited or angry, and burst pulses are thought to convey information about a dolphin’s emotional state. Some scientist have found a very specific burst signal produced by bottlenose dolphins that appears to be a ‘play’ signal – indicating to other dolphins that ‘it’s time to for games, so I’m not really being aggressive’. Burst pulses can be extremely loud, and dolphins may use them during aggressive encounters – possibly to hurt the ‘ears’ of other dolphins. Burst pulse sounds are often seen in social situation where males are herding female dolphins, where burst pulses are directed at the genital region of the fleeing females. They have also been observed when a mother emits a loud burst pulses directed at a misbehaving calf. Different kinds of burst pulse sounds used during aggressive encounters have been given names like ‘squawks’ and ‘barks’ – these click trains are often produced so rapidly that to the human ear, they sound like a continuous sounds, but in reality that are a series of tightly packed clicks. It’s not always easy to tell the difference between a burst pulse and an echolocation click train, and scientists are just now learning about how dolphins use burst pulses in social situations.

One interesting sound that we’ve discussed on previous episodes of the dolphin pod is the pop-creak sound that has been recorded from the Indo-Pacific dolphins around Mikura Island Japan. It sounds like a pop followed by what can be described as a bouncing ping-pong ball, and is often heard during aggressive chase encounters. Some scientists have described a similar pop sounds for other species as well – here is an example.

Non Vocal Acoustic Cues
Dolphins also produce a number of non-vocal sounds that they use for communication. Non-vocal in this sense means any sound that is not produced using the organs within a dolphin’s vocal area (e.g., air sacs, the larynx, etc) that nonetheless produce sound. For a human, screaming is a vocal sound, whereas clapping your hands together is a non-vocal sound. Here’s a list of non-vocal sounds that many species of dolphins use on a regular basis:

Tail slaps (or lob tailing): dolphins often hit the surface of the water with their tail (flukes), producing a very loud booming sound that can transmit great distances in the water. Often a tailslap is a sign of aggression, but this need not always be the case. Tail slaps may mean many things in many situations – for example, a signal that it is time to leave the area. It may simply be a means of getting the attention of friends who are some distance away. Some dolphins and whales also slap their tails as a means of hunting fish – stunning the fish with a powerful blow. This of course is not communication.
Flipper slaps: just like they would do with their tails, dolphins slap their flippers (that is, their pectoral fins) to sound. They may slap their flippers on the surface of the water, or onto their own body (e.g., their belly). This likely produces a similar effect to the tail slap.

Tail Slap:

 

Jaw claps and jaw pops: dolphins can produce extremely loud sounds by rapidly clamping their jaws together. This behavior bangs their teeth together, producing an acoustic signal that transmits large distances. Jaw claps are generally understood to be an aggressive signal, used as a threat. But jaw clapping also occurs during play – the difference between real aggression and play aggression is often very subtle, just like in the case of humans.

Jaw Clap:

   

Chuffs: dolphins exhale rapidly, and you can often hear the sound of an exhaling dolphin if you happen to by nearby when they break the surface. Dolphins may also exhale rapidly through their blowhole as a communicative signal, producing a loud sound called a ‘chuff’ – a chuff is another signal thought to denote aggression.

Breaches: Many cetacean species engage in breaching behavior which includes part of the body or the entire body leaving the water before crashing back into the surface. Some Breaches produce loud sounds (sometimes called percussive sounds) with many low frequencies that travel long distances. Breaching may occur for a variety of reasons – possibly it is a method of removing remoras or other parasites, but more than likely it is a communicative signal. Breaching may produce sounds that convey information about emotional or motivations states, or the sound produced may tell distant friends about a dolphin’s position and the direction it is moving. Breaches may help herd prey during hunting situations. Spinner dolphins produce dramatic spinning leaps which also produce loud sounds upon re-entry – given that many of these leaps are performed at night, these may be leaps whose primary purpose is the generation of noise. Scientist have just begun to classify the subtle differences between types of breaching behavior, and are beginning to understand how small changes in the structure of the breach may in fact communicate vastly different information in various situations.

Humpack Whale Breaching: 

  

Bubbles: dolphins often blow bubble streams and bubble clouds in a variety of social situations, and while these are primarily visual signals, the production of a large bubble cloud also produces a distinctive noise that can likely be heard over short distances.

Visual Cues
Although humans generally tend to think of communication occurring with sound (thanks in part to our reliance on language), much communication happens within the visual modality – both for humans and for dolphins. Visual cues include everything from gestures to movements to coloration. Let’s explore some of the common visual signals used by dolphin species:

Body coloration, spots and stripes: many species of dolphins have evolved complicated body markings that communicate information. For example, Atlantic spotted dolphins slowly develop spots as they age, with adult dolphins being covered in mottled spot patterns – this quickly conveys information about a dolphin’s age. Many color patterns – like counter-shading and the distinctive black and white markings of orcas – are likely used for camouflage or to help when hunting prey species. However, some of the markings also help species to quickly tell the difference between animals belonging to the same or different species. Some species of dolphin like Risso’s dolphin, accumulate scars and bite marks after a lifetime of fighting with other animals, and the amount of scarring seen may indicate to others that the animal is either a veteran fighter, or low on the totem pole.

spotted dolphins

Sexual dimorphism: for many dolphin species, there is an obvious difference between the males and females of the same species. In general for most species, males are larger and bulkier, although specific body parts for species often differ between males and females, for example longer rostrums, darker colors, etc. Sometimes these signals evolve as a means of competition between males – larger males are larger because they need to fend off competition from other males. Male Amazon river dolphins accumulate scars all over their body which turns their skin bright pink, making it easier to pick out males from females.  Male narwhals usually have a single long tusk – unlike females who rarely develop a tusk. This may be a signal to other males about the size and power of the individual sporting the biggest, manliest tusk. For the harbor porpoise, the female is actually larger than the male – but for the sperm whale, males are as much as three times larger than the females. These differences between the sexes signal vital information that individual use to determine how to approach social situations.

Postures: aside from static visual signals like coloration and body size, dolphins produce a number of visual signals. They can signal other dolphins with body postures – for example, by forming their body into an S-shape posture they convey anger or aggression. Some scientists speculate that this S posture is in fact an imitation of the S shaped posture assumed by sharks – something that also conveys aggressions for sharks. So in essence, dolphins may be pretending to be an angry shark. During aggressive encounters, dolphins will also flare out their pec fins in an attempt to make themselves look larger, and open up their jaws – a threat signal. We have witnessed an interesting behavior in Japan where a dolphin adopts a vertical position in the water, and slowly sinks to the sea floor without moving its body at all – the precise meaning of this position and behavior unknown.

Shark s-posture: 

s-posture

 Two dolphin groups fighting - pec flares, etc:

  

Bubbles: dolphin often release bubbles from their blowhole when making whistle sounds, although the release of bubbles does not always coincide with the production of whistles. Bubbles appear to be an extra communicative signal, and can take a variety of forms: bubble streams, bubble clouds, and bubble rings. A large bubble cloud is a conspicuous signal, and often is produced as a threat.

Dolphin blows a bubble cloud: 

 


Gestures: dolphins of course do not have arms or hands, and yet they produce a number of subtle movements that could be understood to be meaningful gestures. For example, a dolphin shaking its head back and forth rapidly, an open jaw, or dipping its head during a frontal approach is often a sign of aggressions. Looking or swimming away, as well as flinching may be a sign of submission.

Dolphin jaw threat: 

 

Synchronous behavior: dolphins have an unusual ability to imitate the behavior of other dolphins, as well as human researchers. In the wild it is thought that mirroring the behavior of your dolphin friends is a signal to other dolphins that the you are in a close relationship with your partners. Male alliances in Shark Bay Australia can synchronize their movements  perfectly, breaking the surface and taking a breath at exactly the same time, and executing turns and twists underwater with perfect precision. This synchronous swimming displays constitute a strong visual signals to anyone who is watching. When groups of dolphins are stressed or threatened, they often group together and synchronize their behavior – perhaps to display solidarity and group cohesion.

Aerial Displays: We’ve already discussed how jumping out of the water created a percussive sound when the dolphin land on the water’s surface, but it also produced an impressive aerial display when the dolphins are airborne. These displays can be viewed both from above and below the water, and may be used to convey information about the direction of travel, location of food or general excitement levels. They may also serve to reinforce social bonds, and may also be effective in herding fish. Some have speculated that impressive aerial displays may also occur during contents – where individuals try to out-do each other.

Spinner dolphins jumping: 

  

Object Carrying: Some dolphins in Australia have been observed using sponges as foraging tools – not a communicative signal at all, but in the Amazon River, the Boto (or animal river dolphin) has been seen carrying sticks and rocks in its mouth apparently as a visual display meant to wow potential mates. Males will collect objects and often swim out of the water holding the rocks or sticks in the air before slowly sinking back into the water. These object carrying displays may signal to the females that she has a hunky, strong male on her hands that is worth mating with.

A Boto carrying seaweed: 

Boto with seaweed

 

Poop: There is even one suggestion that dolphins might use poop as a visual signal! A few colleagues of ours from Japan have tested the idea that dolphins may poop directly in the path of human swimmers and other dolphins as a kind of warning signal. This ideas is still in the early stages of development, but it’s certainly worth noting!

Tactile Cues

Perhaps one of the most important modes of signaling in a dolphin’s world is the use of touch. Dolphins have skin that is quite sensitive to even the lightest touch – much like the skins of human beings. Dolphins are know to rub their bodies up against each other, but also to engage in intricate rubbing behaviors using the pectoral fins. Dolphins will rub their fins into the fins of other dolphins, engaging in a behavior that looks a lot like holding hands. They will also rub the bodies of their friends, moving their fins rapidly over the face, flank or genital region, producing what is likely to be a pleasurable sensation. Sometimes dolphins will seek out rubs by positioning their bodies under the fin of their friend. Researchers have observed a behavior where dolphins will rest their fin on the back of their friend, holding it in place for hours at a time – likely a signal to other dolphins of their friendship. Most all of the tactile behavior I mention here is thought to be a sign of friendly, affiliative contact.

But not all contact behavior is friendly. During aggressive encounters, dolphins can body slam each other, butt heads and ram each other with their rostrums. They also smack each other with their powerful flukes, and have even been observed leaping out of the water each other and slamming into each other while airborne. With sensitive skin, these kinds of aggressive contacts surely must hurt, and these are clearly aggressive signals.

Echolocation
Some people suggest that dolphins are able to share complex 3D images with each other using their echolocation, and often label this something like ‘holographic communication’. At present, there is no evidence that a dolphin’s echolocation ability is able to transmit anything like an image to other dolphins, so this suggestions is purely fanciful at this point. However, it has been shown that a dolphin who is positioned close to their friend can overhear the click echoes that are produced by their friend who may be echolocating on an object. By listening to these echoes, a listening dolphin might get a mental image of the object even though he/she is not engaging their own echolocation. This is not necessarily a form of communication – unless of course dolphins purposely echolocate on objects because they know that their friend will be receiving the click echoes. In this case, it may be something like communication – there is not yet any evidence that this is the case, although scientists are actively researching this area to learn just how dolphins use their echolocation in the wild.

Summary
There is of course much more that could be said about the ways in which dolphins communication, and I could talk for hours about this subject. But the information presented here should serve as a brief overview – enough to whet your appetite. For more information, have a look around the Dolphin Communication Project website, and listen to previous episodes of the Dolphin Pod where we cover some of these topics in more detail.



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Kids' Science Quickie



Kids' Science Quickie: Cookie cutter sharks

Dolphins and sharks are by no means friends. In fact, after humans, sharks are probably the #1 killer of dolphins in the wild. But not all sharks are deadly – and some species of shark , like the cookie cutter shark, would prefer that their dolphin victims stay alive after an attack. The cookie cutter shark is a relatively small shark, and it makes its living by biting off small chunks of its victim’s flesh – usually in a circular pattern. By taking out a painful but not necessarily fatal plug of flesh from a dolphin, the shark will get its meal, and the dolphin will live to see another day, and possibly provide a second meal to the shark the next time it gets hungry. To see images of a cookie cutter shark and a dolphin with a cookie cutter shark bite, visit thedolphinpod.com

Cookie cutter sharks:  

cookie cutter shark

Cookie Cutter Shark Bite on a Dolphin: 

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Dolphin Quiz



Name a species of dolphin that does not produce any whistle sounds

The winner of last week’s quiz was voyager, who correctly stated that hind limbs can be seen in a developing dolphin embryo – these limbs will disappear by the time the dolphin is born. Now, for this week’s quiz: name a species of dolphin that does not produce any whistle sounds.  Think you know the answer?  Winners will randomly be chosen from the correct answers, and will be announced on next week’s show.     

 

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Wrap-up:

That’s it for this week’s edition of The Dolphin Pod – thanks for tuning in. If you would like more information about the stories from this week’s episode, check out thedolphinpod.com. If you’ve got questions or comments about this week’s podcast episode, please contact us through the website. Why not consider signing up for the Dolphin Communication Project’s online community? You’ get access to a forum where you can discuss the The Dolphin Pod with other listeners. The DCP website offers a chance to adopt one of our dolphins from the Bahamas, as well as learn more about volunteer, internship and ecotour opportunities.

Don’t forget to join us next week for more dolphin science news and info. And remember, the dolphin pod is only a click away.

Tagged under
Dolphin personalities, dolphin mittens (flippers), dolphin news (Episode 9)
13 December 2019

Dolphin personalities, dolphin mittens (flippers), dolphin news (Episode 9)

In this week’s episode, we will review breaking Dolphin News from around the world, focus our Science Spotlight on dolphin personalities, and in our Kids’ Science Quickie, we’ll discuss dolphin mittens.

 
Dr. Stan Kuczaj

 

 

 

In this week’s science spotlight, we will be discussing dolphin personalities. For this episode, I interview Dr. Stan Kuczaj. Dr. Kuczaj is a professor of psychology at the University of Southern Mississippi, where he is the director of the Marine Mammal Behavior and Cognition program at USM. He was kind enough to join us today so we could discuss his research into dolphin personalities.

 

 

DolphinPod News

 

Dolphin saves stranded whales, Banish the Bags

Moko, a lone sociable dolphin living off the coast of New Zealand, purportedly saved two stranded pygmy sperm whales. Malcolm Smith, a local conservation officer, had attempted to push the stranded whales back into deeper water multiple times, but to no avail. When Moko arrived on the scene however, the whales apparently followed her past a dangerous sandbar and out into the open ocean.  While it is unlikely that Moko gave the whales specific instructions to follow her to safely, it certainly appears like her presence was instrumental in helping save these two whales from certain death.

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Banish the Bags campaign

The Daily Mail, a UK based newspaper, has launched a campaign to banish the use of plastic bags in Britain, citing the horrendous environmental damage that discarded bags cause. Dolphins and other marine animals, as well as land based animals and birds regularly eat or become entangled in discarded plastic bags, leading to slow and agonizing deaths due to starvation or suffocation. The Daily Mail is petitioning the UK government and local chain stores to implement an outright ban on bags, or at the very least to begin a scheme to charge customers for the use of plastic bags as a means of reducing the number of bags the end up in circulation. Thanks to the campaign, many retailers and supermarkets have already begun pledging to reduce the number of plastic bags they distribute.


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 Science Spotlight
Dolphin personalities

Listen to the interview:

In this week’s science spotlight, we will be discussing dolphin personalities. For this episode, I interview Dr. Stan Kuczaj. Dr. Kuczaj is a professor of psychology at the University of Southern Mississippi, where he is the director of the Marine Mammal Behavior and Cognition program at USM. He was kind enough to join us today so we could discuss his research into dolphin personalities.

Dr. Stan Kuczaj

More information and links: 

The Marine Mammal Behavior and Cognition program at USM

Sam Gosling’s page on animal personalities at the University of Texas

Highfill, Lauren E.; Kuczaj II, Stan A.  Do Bottlenose Dolphins (Tursiops truncatus) Have Distinct and Stable Personalities? Aquatic Mammals, Vol. 33, No. 3. (September 2007), pp. 380-389.

 

 

 

 


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Kids' Science Quickie
Dolphin mittens (flippers)

Kids' Science Quickie: 

The ancestors of dolphins were four-legged land based animals who walked the earth many millions of years ago. Over the course of evolution, their bodies slowly adapted to life in the ocean, drastically altering their once familiar dog-like appearance. Dolphins evolved a brand new blowhole structure on the top of their head in order to help them breathe, and what was once their nose with two nostrils became a new kind of structure that helps them create clicking sounds that they use for echolocation.  You can see evidence of dolphins’ land-based history by looking at the bones in their pectoral fins. Even though the pectoral fin is shaped a lot like a paddle, the bones that make up the fin still retain the structure of their ancestors: you can easily see what look like 5 fingers and a wrist. It’s almost as if dolphins evolved a giant mitten over their hands to help them steer in the water. To see an image of the bones in a dolphin’s flipper, visit www.thedolphinpod.com

cetacean fin bones

Ceatacean forelimb  - from www.locolobo.org/CetaceanEvolution

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Dolphin Quiz
What anatomical feature do you find in a dolphin embryo that you won't find on a dolphin when it's born?



We had quite a few correct answers to last week’s quiz, and our winner (chosen at random) is Brooke who correctly stated that humpback whales have two openings to their blowhole whereas bottlenose dolphins only have one. Now, for this week’s quiz: name a body part that you will see in the first few months of a developing dolphin embryo that you won’t find on a dolphin calf when it is born.  Think you know the answer? Surf on over to thedolphnipod.com and click on Dolphin Quiz – leave your answer in the comments section. Winners will randomly be chosen from the correct answers, and will be announced on next week’s show.     

 

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Wrap-up:

That’s it for this week’s edition of The Dolphin Pod – thanks for tuning in. If you would like more information about the stories from this week’s episode, check out thedolphinpod.com. If you’ve got questions or comments about this week’s podcast episode, please contact us through the website. Why not consider signing up for the Dolphin Communication Project’s online community? You’ get access to a forum where you can discuss the The Dolphin Pod with other listeners. The DCP website offers a chance to adopt one of our dolphins from the Bahamas, as well as learn more about volunteer, internship and ecotour opportunities.

Don’t forget to join us next week for more dolphin science news and info. And remember, the dolphin pod is only a click away.

Tagged under
Dolphins and whales in the Middle Ages, magnetite, dolphin news (Episode 8)
13 December 2019

Dolphins and whales in the Middle Ages, magnetite, dolphin news (Episode 8)

 
In this week’s episode, we will review breaking Dolphin News from around the world, focus our Science Spotlight on dolphins and whales in the Middle Ages, and in our Kids’ Science Quickie, we’ll discuss magnetite.
 
Dolphin illumination

The age of modern scientific study of dolphins, whales and other animals probably started around the 18th century. Before that time period, what did the average person on the street know about whales and dolphins and how did they come by this information? In today’s science spotlight, we will be speaking with Dr. Ranke de Vries, lecturer in Celtic Studies at Utrecht University in the Netherlands. Dr. de Vries studies ancient manuscripts from medieval periods.

 

 

Dolphin official olympic mascot, Hayden Panettiere receives Wyler prize

Dolphin chosen as official mascot of the 2014 Olympics in Sochi

The people of the southern Russian city of Sochi have chosen the dolphin as the official mascot of the 2014 winter Olympics. The vote was held on March 2nd. Over 130 different ideas were submitted as possible mascots.  Sochi was chosen to host the 2014 Olympics last year, and this will be the first time that Russia will host the winter Olympics.

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Hayden Panettiere to be honored for her work raising awareness of dolphin conservation

Heroes actress Hayden Panettiere will receive the Wyler prize at the upcoming Genesis Awards on March 29th organized by the Humane Society of the United States. The director of the human society stated that “She's an inspiring example to her generation, using her compassion, courage and celebrity to help animals in a very effective way.” Panettiere made the news last year after being involved in a high profile protest in the town of Taiji, where a large dolphin hunt takes places each year. Last year’s winner of the Wyler prize was Sir Paul McCartney.

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 Science Spotlight
Dolphins and whales in the Middle Ages

Listen to the interview:


The age of modern scientific study of dolphins, whales and other animals probably started around the 18th century. Before that time period, what did the average person on the street know about whales and dolphins and how did they come by this information? In today’s science spotlight, we will be speaking with Dr. Ranke de Vries, lecturer in Celtic Studies at Utrecht University in the Netherlands. Dr. de Vries studies ancient manuscripts from medieval periods.   

Dolphin illumination

More information and links: 

Link to Aberdeen bestiary:
http://www.abdn.ac.uk/bestiary/
 
The Medieval Bestiary - animals in the Middle Ages:
http://bestiary.ca/
On this page you can find links to bestiaries and to secondary literature.
 
Medieval Writing - bestiaries:
http://medievalwriting.50megs.com/word/bestiary.htm
 
Information on whales and dolphins in early Irish society:
Fergus Kelly, Early Irish Farming, Early Irish Law Series IV, Dublin, Dublin Institute for Advanced Studies, 1997, ISBN 1 85500 180 2
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Kids' Science Quickie
Magnetite

Kids' Science Quickie:

Have you ever heard of magnetite? Magnetite is a naturally occurring mineral that reacts to magnetic fields.  Scientists believe that many animals may have small amounts of magnetite in their brains, allowing them to sense magnetic fields produced by the earth. Animals like bats and birds (especially pigeons) are thought to navigate large distances without using any clues as to where they are other than the presence and shape of magnetic fields which they can sense using the magnetite in their brains. Whales and dolphins too are thought to have small amounts of magnetite in their brains allowing them to navigate enormous distances across the oceans. Scientists also suspect that some whales and dolphins may strand when the earth’s magnetic fields fluctuate beyond their normal position. Navigating by the magnetic fields they have used their entire lives, whales and dolphins may think that they are in the open ocean, but in reality they are dangerously close to shore. It would be a lot like trying to navigate your living room with a blindfold on after someone had moved around all of your furniture. Even humans have a small amount of magnetite in their brains, so the next time you trip over your shoelaces, you can blame it on fluctuating magnetic fields…

http://upload.wikimedia.org/wikipedia/en/7/7c/Magnetite_Russia.jpg

Magnetite

 

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Dolphin Quiz
What’s the main difference between the blowhole of a bottlenose dolphin and the blowhole of a humpback whale?




We had quite a few correct answers to last week’s quiz, and our winner (chosen at random) is Rebecca Frost who correctly stated that it was a trick question: dolphins do not have bones in their dorsal fins, only fibrous tissue. Now, for this week’s quiz: what’s the main difference between the blowhole of a bottlenose dolphin and the blowhole of a humpback whale? Think you know the answer?. Winners will randomly be chosen from the correct answers, and will be announced on next week’s show.  

 

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Wrap-up:

That’s it for this week’s edition of The Dolphin Pod – thanks for tuning in. If you would like more information about the stories from this week’s episode, check out thedolphinpod.com. If you’ve got questions or comments about this week’s podcast episode, please contact us through the website. Why not consider signing up for the Dolphin Communication Project’s online community? You’ get access to a forum where you can discuss the The Dolphin Pod with other listeners. The DCP website offers a chance to adopt one of our dolphins from the Bahamas, as well as learn more about volunteer, internship and ecotour opportunities.

Don’t forget to join us next week for more dolphin science news and info. And remember, the dolphin pod is only a click away.

Tagged under
Dolphin sleep behavior, dolphin teeth, dolphin news (Episode 7)
13 December 2019

Dolphin sleep behavior, dolphin teeth, dolphin news (Episode 7)

In this week’s episode, we will review breaking Dolphin News from around the world, focus our Science Spotlight on dolphin sleep, and in our Kids’ Science Quickie, we’ll discuss how you can tell how old a dolphin is by looking at its teeth.

Sleep

 

 Dolphins sleep behavior is fundamentally different to that of humans

 

In this week’s science spotlight, we will be discussing sleep in dolphins and humans. For this episode, I interview Dr. Brendan Lucey. A graduate of Johns Hopkins School of Medicine, Dr. Lucey is currently a clinical neurophysiology fellow at Brigham and Women’s hospital at Harvard Medical School, and has a keen interest in sleep and sleep disorders. He was kind enough to join us today so we could discuss how sleep works in dolphins, and how it compares to sleep in humans.

 

   

DolphinPod News

 New hearing pathway discovered, US Navy must abide by injunction, drunken men harass dolphin

Scientists discover a new pathway for hearing in beaked whales

A group of scientist published an article in the journal BIOINSPIRATION & BIOMIMETICS earlier this month describing a newly discovered sound reception channel in the skull of Cuvier’s beaked whale. Using advanced computer modeling systems, the researchers discovered an area  between the lower jaw bones, in the throat area, that appears to receive sound vibrations and direct them to the inner ear via a fatty channel. Traditionally, toothed whales are thought to receive sound vibrations through fatty channels in their lower jaw, but this new sound transmission channel – termed the gular pathway – may in fact be a more efficient means of receiving sound, and may perhaps even be the primary path of sound reception. The authors discuss the possibility that the gular pathway might be important to species other than Cuvier’s beaked whale, including bottlenose dolphins.

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Judge orders US Navy to comply with no-sonar law

A federal judge has ruled that President Bush's exemption of the US Navy to the National Environmental Policy Act, which limits sonar use off the coast of California, has no legal standing, and that the Navy must comply with the court ordered injunction. The injunction creates a 12 mile no-sonar zone off the cost of Southern California in an effort to protect endangered marine species from potentially deadly Navy sonar.


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Two drunken Englishmen charged with interfering with a dolphin

After returning from a trip to the pub, two intoxicated Englishmen bypassed signs asking people not to harass Dave the dolphin, a friendly dolphin living off the coast of Kent in England, and attempted to swim with Dave. The incident occurred in the wee hours of the morning back in June of 2007. According to the defendants, swimming with Dave was “cheaper than an exotic swimming with the dolphins holiday”. The men attempted to ride Dave, pulled on her dorsal fin and, according to local dolphin experts, ignored signs that the dolphin was displaying aggressive behaviors towards them. Local authorities were called in after witnesses reported the incident, and the men were promptly arrested. The landmark case is currently underway in England, and is the first time that anyone has been charged with the crime of ‘interfering with a dolphin’. Dave has not been seen since December 2007, and is presumed dead.


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 Science Spotlight
Sleep in Humans and Dolphins

In this week’s science spotlight, we will be discussing sleep in dolphins and humans.

Listen to the interview:

 For this episode, I interview Dr. Brendan Lucey. A graduate of Johns Hopkins School of Medicine, Dr. Lucey is currently a clinical neurophysiology fellow at Brigham and Women’s hospital at Harvard Medical School, and has a keen interest in sleep and sleep disorders. He was kind enough to join us today so we could discuss how sleep works in dolphins, and how it compares to sleep in humans.  

Sleep



 

 

 

More information and links: 

Article showing that dolphin mother's and calves rarely sleep during the first month of the calf's life

Article disputing the claims of the previous article, suggesting mother's and newborn calves do in fact sleep during the first month

Article describing an experiment where a dolphin performs a cognitive task every few minutes continuously for 5 days - without dropff in performance

National Sleep Foundation website 

American Academy of Sleep Medicine website

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Kids' Science Quickie
How can you tell how old a dolphin is?

Kids' Science Quickie: 

How can you tell how old a dolphin is? Believe it or not, the easiest way to tell a dolphin’s age is to look at its teeth. Bottlenose dolphins are born with around 25 teeth. Unlike humans, who lose their baby teeth, a dolphin will keep the full set of teeth it was born with for its entire life. And also unlike human teeth, dolphin teeth grow larger by producing growth layers in the root. These layers are visible and distinct for each year of a dolphin’s life. Scientists are then able to determine how old a dolphin is by cutting the tooth in half and simply counting the growth layers that they see, much like you can count the rings inside a tree trunk.  Officially, these layers are called dentinal growth layer groups, and are a very reliable way to tell the age of most dolphin species.

Dolphin tooth section showing growth layers
*image from Quekett Microscopical Club website 

 

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Dolphin Quiz
How many bones are in a dolphin's dorsal fin?



We did not have any winners from last week’s show where we  asked which cetacean species lives the longest. The answer is the Bowhead whale, which is thought to live well over 200 years. Now, for this week’s quiz: how many individual bones are in a dolphin’s dorsal fin? Think you know the answer? Winners will randomly be chosen from the correct answers, and will be announced on next week’s show.  

 

 

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Wrap-up:

That’s it for this week’s edition of The Dolphin Pod – thanks for tuning in. If you would like more information about the stories from this week’s episode, check out thedolphinpod.com. If you’ve got questions or comments about this week’s podcast episode, please contact us through the website. Why not consider signing up for the Dolphin Communication Project’s online community? You’ get access to a forum where you can discuss the The Dolphin Pod with other listeners. The DCP website offers a chance to adopt one of our dolphins from the Bahamas, as well as learn more about volunteer, internship and ecotour opportunities.

Don’t forget to join us next week for more dolphin science news and info. And remember, the dolphin pod is only a click away.

Tagged under
The truth about Dolphin Assisted Therapy, pink dolphins, dolphin news (Episode 6)
13 December 2019

The truth about Dolphin Assisted Therapy, pink dolphins, dolphin news (Episode 6)

 
In this week’s episode, we will review breaking Dolphin News from around the world, focus our Science Spotlight on Dolphin Assisted Therapy, and in our Kids’ Science Quickie, we’ll discuss pink dolphins.
 
In this week’s science spotlight, we will be discussing a popular but highly controversial form of animal therapy known as Dolphin Assisted Therapy. This episode features an interview with Dr. Lori Marino, senior lecturer in the Neuroscience and Behavioral Biology Program, at Emory University. Scroll to the bottom of this page for a full transcript of the interview.
 

 DolphinPod News

Deaths of Hector’s dolphins are on the rise

According to the New Zealand Department of Conservation, the number of Hector’s dolphins found dead in 2007 has nearly doubled since 2006. The endangered Hector’s dolphin is one of the rarest dolphins in the world, with a population estimated at just 7,000 individuals. Twenty five animals were found dead in 2007, up from 15 in 2006. Although some of the deaths were confirmed as being from natural causes, it is likely that a number of individuals died after being accidentally caught in fishing nets.  Before the introduction in the 1970’s of a particularly dangerous kind of fishing net known as the ‘set net’, there were as many as 26,000 Hector’s dolphins in New Zealand waters. Conservationists are calling for a total ban of set nets in order to stem the tide of dolphin deaths. 

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Bush exempts US Navy from Coastal Zone Management Act

Bush signed an exemption to environmental laws for the US Navy on January 15th, which could allow the Navy to conduct training exercises off the coast of California using mid-frequency active sonar, a known threat to endangered marine mammals. After lobbying by conservationist, a federal court issued an injunction in early January requiring the Navy to create a 12-nautical-mile, no-sonar zone along the Southern California coast. The Navy is currently in a legal battle in federal court, seeking to lift the ban on the use of mid-frequency sonar which it claims is required to effectively train its soldiers to detect enemy submarines.  Mid-frequency sonar has been linked to disturbance of whale and dolphin behavior, mass strandings and possibly even death caused by tissue damage for those animals exposed to the extremely loud sonar pings. The president’s exemption will not allow the Navy to by-pass the injunction, although it will strengthen their case in federal court.


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 Science Spotlight

The truth about Dolphin Assisted Therapy

For this week’s episode, I interview Dr. Lori Marino, senior lecturer in the Neuroscience and Behavioral Biology Program, at Emory University about Dr. Lori MarinoDolphin Assisted Therapy. Lori’s research focuses on brain and behavioral evolution in mammals, and she has written numerous scientific articles on dolphin cognition, dolphin behavior and dolphin intelligence. In addition, she has written a handful of articles discussing the pros and cons – mostly cons – of the highly controversial practice know as Dolphin Assisted Therapy.

 *Read a full transcript of the interview at the bottom of this page *

More information and links:

Read more about the WDCS campaign to ban Dolphin Assisted Therapy 

Dr. Marino and Dr. Lilienfeld's 2007 article:  “Dolphin-Assisted Therapy: More Flawed Data and More Flawed Conclusions” 

Read a report by the WDCS on Dolphin Assisted Therapy 

IDAT pamphletf you have questions about Dolphin Assisted Therapy or Dr. Marino's research, you can contact her here.  

Dr. Marino's CV 

WDCS Dolphin Assisted Therapy leaflet

Discuss Dolphin Assisted Therapy in the DCP forum 

 

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Kids' Science Quickie

Pink dolphins

If you’ve ever seen the Disney film Dumbo, you are likely familiar with Pink Elephants. But are there pink dolphins too? In fact, there are two species of dolphins that have pink colored skin. The Amazon River dolphin is famous for having pink colored skin, and is often called the Pink River Dolphin. But not all Amazon River dolphin have pink skin: the pink color accumulates slowly over time, and is the result of a buildup of scar tissues caused by fights with other dolphins. There is another dolphin famous for its pink complexion: the Indo Pacific Humpback dolphin. These dolphins live in the Indian and Pacific oceans, and not all populations have the same coloring. Some varieties are born pink, but become a darker grayish color as they get older. Some are born gray, but get more pink or even white as they get older, and some are nearly entirely white their entire lives.  Of course any species of dolphin or whale could be born with albinism, a condition where they lack any color pigmentation in their skin. This will also result in pink-ish or white skin color, and has been observed in many species. Last year, a pink bottlenose dolphin was spotted in Louisiana, and there is a famous white humpback whale named Migaloo who lives off the coast of Australia. 

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Dolphin Quiz



Which cetacean species lives the longest?

Last show’s winners were Tito and Chiara who correctly stated that Risso’s dolphins get their white scratches from fights with other dolphins involving a whole lot of biting. Now, for this week’s quiz: of all the species of dolphins, whales and porpoise, which individual species (according to the latest scientific research) is known to the live the longest, and how old can they get? Think you know the answer? Surf on over to thedolphnipod.com and click on Dolphin Quiz – leave your answer in the comments section. Winners will randomly be chosen from the correct answers, and will be announced on next week’s show. 

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Wrap-up:

That’s it for this week’s edition of The Dolphin Pod – thanks for tuning in. If you would like more information about the stories from this week’s episode, check out thedolphinpod.com. If you’ve got questions or comments about this week’s podcast episode, please contact us through the website. Why not consider signing up for the Dolphin Communication Project’s online community? You’ get access to a forum where you can discuss the The Dolphin Pod with other listeners. The DCP website offers a chance to adopt one of our dolphins from the Bahamas, as well as learn more about volunteer, internship and ecotour opportunities.

Don’t forget to join us next week for more dolphin science news and info. And remember, the dolphin pod is only a click away.

 

*************FULL TRANSCRIPT OF THE INTERVIEW****

JG = Justin Gregg, host of The Dolphin Pod
LM = Lori Marino

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JG: I am speaking with Dr. Lori Marino, senior lecturer in the neuroscience and behavioral biology program at Emory University. Lori’s research focuses on brain and behavioral evolution in mammals, and she has written numerous scientific articles on dolphin cognition, dolphin behavior and dolphin intelligence. In addition, she has written a handful of articles discussing the pros and cons – mostly cons – of Dolphin Assisted Therapy. Thanks for talking with us today, Lori.

 

LM: O, you’re very welcome.

 

JG: Can I get you to first explain what Dolphin Assisted Therapy is, and what it claims to do?

 

LM: Yes, sure. Dolphin Assisted Therapy is a form of animal assisted therapy. It’s an industry that is marketed as a treatment for a variety of illnesses – everything from autism to cancer. Basically, it involves patients, either children or adults, entering the water with captive dolphins, typically, and they engage in several activities from swimming with and riding on the dolphins to just touching the dolphins, to feeding the dolphins, and typically there are several sessions that are offered at usually between three and five thousand dollars for the whole treatment. So it basically involves people getting into a tank or a pool with dolphins and engaging in different interactive activities.

 

JG: And where do they offer these programs?

 

LM: DAT is offered all over the world. There are several facilities in Florida, in Hawaii, in the Bahamas, but there are also facilities all over Asia, all over Europe, the Middle East, South America, Dubai, I mean they are literally popping up everywhere.

 

JG: Hm. And how did you develop an interest in investigating the claims of DAT?

 

LM: Well, as you know I have been studying dolphins for many years and I began to get interested in the effects of captivity and the effects of human-dolphin interaction. And then also I have a co-author, Scott Lilienfeld who is a clinical psychologist, and he is very interested in pseudo-scientific claims. So we put our interests together and we began to realize that this was something that needed to be investigated. And then I became very interested in that, and concerned about the proliferation of a pseudo-science so we decided we would just take a look at the literature to see what it says.

 

JG: The two of you have written an article that appeared recently in 2007 called ‘Dolphin-Assisted Therapy: More Flawed Data and More Flawed Conclusions’. Can you describe a little bit about that paper and what it discusses, and what you have found?

 

LM: Yeah, sure. This is a follow-up to a similar study that we published in 1998, and basically what we did is, we looked at all the peer-reviewed papers on dolphin therapy since 1998 and we found that there were five published papers in the peer-reviewed literature that claimed that there was some therapeutic effectiveness to DAT, to Dolphin Therapy. So what we did is we conducted a rigorous analysis of the methodology used in these studies to see if the conclusions were warranted, and we basically applied basic research and knowledge, looked at whether or not these, given what each study, how each study was conducted whether the conclusions were warranted and the study was a valid study. And we found that all of the studies were so lacking in validity that none of the conclusions were warranted. And this echoed the findings of our 1998 paper, so basically to date, we have done a rigorous analysis of the methodology used in all the peer-reviewed DAT or Dolphin Therapy literature, and there is currently absolutely no evidence that this type of therapy is effective for treating illnesses.

 

JG: You list in the paper a number of threats to validity, but I just want to pick some of the big ones, and just have you quickly discuss what they mean in terms of these therapies. The first is the placebo effect. Can you describe what that is, and why it is such a problem?

 

LM: The placebo effect is a ubiquitous effect that you have to guard against in all treatment studies, and there is no exception here. Basically the placebo effect is improvement from someone expecting improvement, so if you give somebody a pill and say ‘this pill will make you feel better’, they will feel better, but you don’t know whether or not it is because you have told them that they will feel better, or whether there is a chemical in the pill that is actually helping them. So if people know the purpose of the therapy, then they are going to show some improvement that has nothing to do with the specific therapy, and none of these studies control for the placebo effect. And so what that means is that even though the placebo effect may actually be “real”, it may have nothing to do with swimming with dolphins.

 

JG: So it is not necessarily the dolphin – it could have been anything.

 

LM: It could have been anything, right, exactly, and the thing that it would be in the placebo effect would be telling someone that you are going to help them, that has a positive impact.

 

JG: Right, like the sugar pill, essentially. There are a couple of other threats; one of them is novelty. How does that affect the validity of these studies?

 

LM: That is another sort of non-specific effect, and basically, this has to do with the positive effects of any new and exciting experience. So we know that if you do something fun, you do something novel, you do something exciting, that it is going to be uplifting. It is going to have a good effect upon your mood, at least in the short term. And it is fun to swim with dolphins, it definitely is, but it does not make it therapy, and again, you have to keep in mind that this effect, the novelty effect, was never accounted for in any of these studies. So it could very well be that anything fun and exciting and new, is going to have a short-term positive impact on one’s mood, or one’s attitude and so on and so forth.

 

JG: So again, this is sort of the idea that there is nothing special about the dolphins -

 

LM: Nothing special about dolphins

 

JG: - it’s just that it was fun. It could have been snowboarding or something, anything.

 

LM: Exactly.

 

JG: So in these studies they had not really controlled for that, they had not another group going out snowboarding to see if they had the same effects.

 

LM: They did not control for that. The controls for all of these really confounding factors were non-existent.

 

JG: Right, which is a big problem, obviously.

 

LM: A huge problem.

 

JG: And there is another one you mentioned; ‘construct confounding’ I think is the term you used. Can you describe what that is?

 

LM: Very simply, construct confounding is a fancy term for the fact that when you put someone through an experience like a treatment with a drug or DAT, that there are many different factors in that experience that would account for the outcome. And so without experimental control you really cannot tell in DAT studies whether there was something about being in the water that was perhaps mood-elevating, or is it any large animal – does it have to be a dolphin? Could it be the extra attention that the students get, that the clients get from the tutors and the trainers? Again, is it the new environment? So there is no way to disentangle these factors to determine whether or not there is anything special about the therapy with the dolphins per se. None of these studies really did that adequately.

 

JG: So each of the five studies, they failed to sort of separate out all those variables –

 

LM: Absolutely.

 

JG: - just threw them all in a soup together and said ‘it works’.

 

LM: And just decided that it was the interaction with the dolphins that was the therapeutic agent when in fact they had not shown that at all.

 

JG: Right. Okay. Out of curiosity, because these are some fairly major flaws -

 

LM: These are major methodological flaws, I mean, these are just… what is important to notice is that these are very basic experimental controls that should be done in any good piece of research, regardless of whether it is DAT, and it is just not good research.

 

JG: The papers themselves, they wound up in some credible scientific journals, so I wonder, what are your thoughts on the fact that reviewers during the peer review process should have spotted these and have been a little more conservative?

 

LM: Well, you know, I think that it is unfortunate – I mean, obviously a lot of flawed studies get through to the publication stage and you know, no studies are perfect. But I think it points to the fact that in this domain of research, that we need to be more stringent, and that we need to set the bar a lot higher than it is for publication in this area. And I think that is true for a lot of the literature in human-animal studies, and animal therapy and so forth. For whatever reason it is not as stringent as it really should be.

 

JG: Hmm. You mentioned earlier that you had published a similar paper back in 1998, discussing some other, some previous DAT articles that had come out, and Dr. David Nathanson, I think he was [the author of] at least two of them. He crops up in the media quite a bit, talking about DAT. And in the 1998 paper you did a similar kind of methodological review. Can you quickly discuss what Nathanson’s claims were, and your discussion of them?

 

LM: Yes, sure. Basically, Dave Nathanson argues that DAT, dolphin therapy, increases learning through increased attention focus in kids and people with autism, other forms of developmental disabilities, and so forth. And he has made some pretty extreme claims because he actually has said that he thinks that dolphin therapy is more effective than traditional physical or speech therapy, and in fact these claims are really outlandish. And really, his major hypothesis that for instance the problem with kids with autism is that they cannot focus their attention is just at odds with everything we know in the mainstream scientific domain about what the problem is with autism. So he does not have the right hypothesis, and therefore his thinking about the treatment, why it works, is equally off.

 

JG: Interestingly enough, I was researching him for this interview, and I saw a recent paper, a 2002  {*actually a 2007} paper, where he discusses what looks like they build an animatronic dolphin and put it in the therapeutic pools, and they found that this animatronic dolphin had the same effect on the patients as a regular dolphin. Do you think that that is a sign that he kind of had a change of heart, like he is backing off from his really strong claim that it is special to dolphins? 

 

LM: Well, I do not know, I mean I read that article – it was very interesting. You know, the same methodological issues apply to the animatronic dolphin study as to studies with real dolphins, I mean, a good study is a good study and a poor study is a poor study, regardless of whether you are using a real dolphin or not. And I would say that, you know, if someone could show with good science that there were specific therapeutic effects to swimming with an animatronic dolphin, then you know, I suppose it wouldn’t be objectionable. But again, regardless of whether we are talking about an animatronic dolphin or a real dolphin, the onus is on Nathanson to show the effects with good basic research, and he has not done that yet.

 

JG: So it is kind of the same problem, I mean, you just swapped in a real dolphin - it could still be placebo effects, novelty effects, you do not know if that is the problem.

 

LM: Absolutely. The same problems apply, exactly.

 

JG: Interestingly, and this is going out there a bit, I was researching the websites for places that do offer this kind of therapy and reasons as to why it works – or their claims as to why it works, and there is the AquaThought Foundation online and they make some claims that the reason it is specific to dolphins and not, say, animatronic dolphins, is that dolphins are using their echolocation to somehow change neurotransmitter production or brainwaves and things like that, which is kind of out there from what is standard science anyway. There was a 2003 Brensing et al. paper that you mentioned in your recent article which kind of did it an experiment to talk about the dolphin healing energy idea. Do you think that article will close the door on that idea, or is there still some possible truths about those claims?

 

LM: I do not think there is any evidence that ultrasound can heal in the way people claim in the form of dolphin echolocation. The AquaThought Foundation has made this claim and there is absolutely no evidence to show that dolphin ultrasound has an effect on brain neurotransmitters – that is entirely unfounded. The Brensing paper really did a really good job at disputing these claims, so given that the Brensing paper really did show that there was really nothing much to this claim and the fact that as a neuroscientist I can tell you it is a preposterous claim, and there is no evidence for it, I think it just cannot be taken seriously at this point.

 

JG: Right. Out of curiosity, people speculate about this, and this has a lot to do with different things, but why is it that dolphins have been singled out as the animal that has all these ‘healing powers’ – why is it not pigeons or cats or dogs, why not other animals? What is it about the dolphin that makes them so special to so many different people who have these sometimes fantastic claims?

 

LM: It is so interesting because it is true that there has always been a mythology around dolphins, for thousands of years. It has always been that way – you go back to the ancient Greeks and they made dolphins into gods, and there have always been these sort of spiritual types of thoughts surrounding dolphins and so forth, and really, dolphins are the ultimate New Age animal, they really are, and I think it might have to do with the fact that they are intelligent – people perceive that they are intelligent, and interactive, but at the same time, they live in a strange environment: they live in the water, they are under the water, and mysterious and so there is this juxtaposition of two factors that these are clearly intelligent, curious beings, but they come from a strange world and it could be that those are the kinds of things that reaches folklore. Because it really it true that we know so little about them and so they are quite mysterious.

 

JG: Definitely. So it is sort of a meme running through the population at this point?

 

LM: I think it is, I truly think it is and I think that if you look on the Web and you look at a lot of New Age types of healing sites and things like that, things that do not explicitly have anything to do with dolphin therapy, you will often see dolphins – it is the iconography. So yeah, there people have all kinds of ideas about who dolphins are. 

 

JG: Yes, and so DAT is building on the effect.

 

LM: It is trading on that – exploiting that dolphin folklore, exactly, and people will not buy it when it comes to guinea pigs or cats, but they buy it when it comes to dolphins.

 

JG: So that is an important part then of the therapy, really, this mythology and folklore behind it.

 

LM: Well, it is an important part of getting people to pay thousands of dollars for the therapy.

 

JG: There are a lot of facilities out there all over the world, some of them charging an enormous amount, some of them charging less, some of them making some pretty fantastic claims and some of them making some more innocent claims. Do you feel that there are any facilities offering DAT that are worth visiting?

 

LM: No, I do not, I cannot recommend any DAT facility at this point, and the reason I say that is that there is absolutely no evidence that this is therapy. So any facility that advertises itself as a facility that is offering therapy - it is false advertising. And I think that parents of sick children should be made aware of this. There is no justification for asking people to mortgage their homes and fly halfway around the world to swim for five days with a dolphin – there is just no scientific justification for that. And I think it also desensitizes people to the plight of the animals in captivity. Also, there is a very real potential for harm to a person swimming with a dolphin in captivity – we have seen that time and time again, so really, it is a lose-lose situation for everybody but the people that run these facilities. There is just nothing to recommend it. Now if someone wants to have their children swim with a captive dolphin, and they are not under the expectation that this is therapy, well, you know, there are opinions about that, but the fact that this is touted as therapy is just basically modern snake-oil. And people need to be made aware that they are being exploited very badly in this situation.

 

JG: Playing devil’s advocate here, I am sure that there are people who could argue that even though it is a placebo effect, the effect is real, so being in the water with dolphins has some value for people who are participating in it. So even if there is a problem with this concept, the fact that the dolphins are in a facility otherwise doing nothing – what is the harm in bringing someone to the facility for therapy?

 

LM: Well, I think the harm is the financial cost to the parents, or to the patients, and then I think the harm - there is a real potential for harm to the person swimming with the dolphin. There are numerous documented cases of people that have been seriously injured by captive dolphins. In fact, there was a recent incident in Curaçao where three people were swimming with a dolphin in a marine park and the dolphin launched herself at the people and seriously injured them. And you know, these facilities are not going to want their customers to be aware of these incidents so they are not heavily advertised. So they are putting their lives and the lives of their children at enormous risk. And finally, I think patronizing facilities provides more motivation for people in the marine park industry to go out and capture more dolphins from the wild for these [parks] and I think that if people understood that for the most part these animals were taken from these brutal drives and captures, that they probably would not want to patronize these facilities, but that is hidden from the public. Even captive-born animals have been found to exhibit strong stress responses to people entering their tanks, so again, it really is a lose-lose situation. I mean, the child might – anyone might have a good time swimming with a dolphin, but when you really do think about all these other factors, people need to be made aware that they are contributing to a seriously exploitive industry.   

 

JG: Getting back to the dangers for human participants, I have also heard of the dangers of disease transmission between humans and dolphins. Is that a real problem?

 

LM: Absolutely. Yes, disease transmission is a very real possibility. You have to remember that DAT, even in the United States, is a totally unregulated business. There are no standards, no professional standards for a marine park that hangs out a shingle that says ‘We offer Dolphin Assisted Therapy’, there are no degrees in this, it does not even require that the people involved have degrees in psychology or therapy, so there is absolutely no standards, no professional regulations – so anything goes. And under those circumstances, you really are left to the devices of the people running the facilities.

 

JG: Yeah, you take their word for it, in a way.

 

LM: You have to take their word for it, and they are not going to tell you that this is dangerous and so on and so forth – they want to get you in and get your money. And so disease transmission, injury – all of these things are very real in this industry, and the public is kept in the dark about these things, by and large.

 

JG: You touched a little bit on the dangers not to the humans but to the dolphins involved. Can you talk a little bit about the dangers for the dolphins in the tanks, but also for the impacts that DAT and its popularity has on wild populations?

 

LM: In the United States, DAT facilities have animals that are primarily captive-born, because they have not taken from the wild in several years but there are studies that show that even captive-born animals show stress in captivity. We all know that there are problems with quality of life in a captive environment for any cetacean, and that leads to psychological and emotional problems in these animals that really are only exacerbated when you have people entering the water with them. Many of these animals really do not have much of a choice as to whether they participate in these sessions, even though the people in the marine parks would want to tell you that they do, but in fact they really do not. Now, the worst part of all this is that because dolphin therapy becomes so popular all around the world, it is contributing to a greater and greater degree to the capture of wild dolphins, because outside of the United States, there are very few countries who have a moratorium on taking animals from the wild. So for instance throughout Asia, almost all the DAT and swim programs and just general marine parks are stocked with animals that have been taken from these horrendous drive hunts and these brutal wild captures.

 

JG: Those are like the ones that popped up recently in the news in Japan, in Taiji.

 

LM: In Taiji, every year in Taiji in Japan, they kill tens of thousands of dolphins and other small cetaceans. And what happens is that when these animals are driven into the cove they are slaughtered in an unimaginably brutal way. I mean, their throats are slashed, they are pummelled to death, they die of heart attacks, it is just absolutely one of the worst things you will ever see. And amidst all of this horror you see trainers from various marine parks all over Asia who are there knee-deep in the waters that are basically red with these animals’ blood, and they are picking out the strong, healthy, young dolphins to take with them back to the marine parks. So basically they are using this slaughter as a way to get their inventory, and a live dolphin pays a lot more than a dead dolphin. So by doing this they are maintaining the motivation of the fishermen in Taiji to continue the slaughter and this is happening all around the world. We now know that dolphins taken from the wild in the Solomon Islands have made their way to Dubai for resorts, so people can swim with these dolphins, we know that this happens all over the world. And so when people go to a captive facility, especially outside the United States, and they see these dolphins, I want them to know where these animals came from and for every dolphin that stays alive for a couple of years in a marine park, five or six have died getting that one animal to survive in that facility – at least five or six, I think some studies have shown that the survival rate is one in ten. So they have to think about the carnage behind that scene, and that is what I want people to know about. And it is getting worse, it is not getting better.

 

JG: So in a very real way these DAT programs are directly leading to a reduction in wild dolphin population numbers.

 

LM: They are directly leading to these DAT swim programs, and in general the captivity industry of marine parks, especially outside the United States, is leading to the capture of wild dolphins and it has a negative impact upon wild populations. And as I said, it really is getting worse, and usually none of these drives or wild captures are accompanied by any data on how the population was impacted, so we can only assume that there are negative impacts on wild populations. Certainly the animal welfare issue is one that is just among the worst in the world in terms of what these animals go through when they are captured.

 

JG: So in a way if you are a customer at one of these places and you are paying a large sum of money to swim with a dolphin, and if those dolphins are directly sourced from wild populations, you in a way are paying for that dolphin -

 

LM: You are paying for dolphins to be tortured and captured. And killed. And of course, the people that frequent these facilities do not know this and they are good people, and they need to know this.

 

JG: Can you talk a bit about the people who do visit these [facilities], because you mentioned that these are vulnerable people themselves - so in a way they are being preyed upon with the idea of DAT, because not necessarily being a real therapy at all, they are paying huge sums of money.

 

LM: They are paying huge sums of money; I mean a lot of people come from poor circumstances but they are desperate – they have an autistic child, or a child with cancer, any parent would do anything to help their child. And so you have a very vulnerable population, and many, many people have done things like mortgaged their homes, taken up donations, used all of their savings to go to these facilities with the hope that their child will be helped, and that is just one of the most base forms of exploitation – to exploit the hopes of parents of sick children. I can’t really think of anything worse, and the thing is with these DAT programs, they usually charge several thousand dollars for say a week to two weeks of a few sessions with dolphins, and that does not include getting there and the hotel and everything. So these people end up spending thousands and thousands and thousands of dollars in hopes that they will help their child.

 

JG: So what advice would you have for anyone that is listening who is considering seeking Dolphin Therapy for a loved one who is suffering from a mental or physical condition?

 

LM: My advice is consumer beware – do not be fooled. Save your money, it is snake-oil, and no matter how you look at it, whether you care about the fact that your child could be in danger by swimming with this wild animal; whether you are concerned about the fact that you are contributing to these beloved animals being taken from the wild – wherever your concern lies, it is a losing proposition. Do not give in to these claims, because there is nothing to it – it is snake-oil. And so this is really an example of the worst kind of exploitation of vulnerable parents and sick people and animals. So just be smarter, buyer beware, and do not give in to the temptation, because they are being exploited.

 

JG: Are there any resources online or campaigns that you know of where you can learn more about DAT and the problems with it?

 

LM: Yes, there is a campaign that I have been working on with the Whale and Dolphin Conservation Society [WDCS], and they can go to the Whale and Dolphin Conservation Society website and find a lot of information on DAT, the information on the studies that I did with Scott Lilienfeld are on there, and some of the other studies that look at disease transmission and so forth. If anybody wants to contact me by e-mail, I am perfectly happy to be available to send out materials and also, talk with them.

 

JG: Fantastic – I will put some resources up on the Dolphin Pod website to the WDCS and [for] people who may want to contact you directly.

 

LM: Yes, absolutely, that will be fine.

 

JG: Great! Well, I am going to wrap this up, so thanks very much for this interview – this is fantastic information. I hope people learn something.

 

LM: I hope so, I hope so, I think the only way that this is going to end is if we let the public know that they are being victimized – not only the animals, but the public.

 

JG: Fantastic. Well, thanks very much Lori!

 

LM: Thank you.

Tagged under
Humpback whale echolocation, Pelorus jack, Dolphin News (Episode 5)
13 December 2019

Humpback whale echolocation, Pelorus jack, Dolphin News (Episode 5)

In this week’s episode, we will  review breaking Dolphin News from around the world, focus our Science Spotlight on humpback whale echolocation, and in our Kids’ Science Quickie,  we’ll discuss Pelorus Jack.

 

DolphinPod News

 

Sonar ban canary island, Risso dolphin rescue in Maui, Tasmania dolphin stranding rescue

Cambodia launches plan to save the endangered Irrawaddy dolphin. The Mekong River in Cambodia is home to approximately 100 Irrawaddy river dolphins – a critically endangered river dolphin species. The largest threat to this species is fishing, which leads to either accidental entanglements, or depleted food resources for the dolphin. In an effort to reduce human impact, the Cambodia government is launching a program to encourage tourists to the area to view the dolphins.  The program will help decrease use of the river for food by promoting alterative food sources for local villagers, as well as boost the local economy by developing local dolphin-watching tourism. 

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A man in Scotland has been fined for harassing dolphins while jet skiing. Believed to be the first successful prosecution of its kind, the jet skier was fined 500 Pounds for recklessly harassing a group of dolphins near Moray Firth in June of 2006.  Moray Firth in Scotland is home to a resident population of approximately 130 bottlenose dolphins. Dave MacKinnon, a wildlife crime officer for Grampian Police, told the BBC that “this incident will send a strong message to people who use the marine environment for their work and leisure. What we ask is that people using such crafts do so in a responsible manner for their safety and that of others including protected wildlife.”

 

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The New Zealand government has delayed a decision on protective measures for the endangered Maui’s and Hector’s dolphins. The government is reviewing a threat management plan calling for set-netting and trawling to be prohibited within two nautical miles of the Te Wae Wae Bay shore in order to protect Hector’s and Maui’s dolphins from possible entanglement. WWF-New Zealand released a statement saying “We are deeply concerned that the Government is delaying protecting our dolphins.  The decision means that more dolphins will die in fishing nets this summer.” New Zealand Fisheries Minister Jim Anderton and Conservation Minister Steve Chadwick announced that because of the huge number of submissions on the proposed plan, a decision would not be made until March of 2008.


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Science Spotlight


Do humpback whales echolocate?

There are many things that differentiate odontocetes or ‘toothed whales’ from mysticetes or ‘baleen whales. ’ The most obvious difference of course being that odontocetes have teeth and mysticetes have baleen. Coming in at a close second, however, is the fact that odontocetes echolocate while mysticetes do not. But, hold the boat folks:  this fact may not be a fact after all.  Just last year a team of scientists published an article in the Royal Society journal Biology Letters describing the first-ever recordings of something they termed “Megapclicks”: strange click sounds produced by humpback whales. The name Megapclick is derived from the scientific genus of the humpback whale Megaptera – combined with the word click.

In order to understand why this is an important discovery, let’s have a quick review of what echolocation clicks are all about .  Here is what dolphin echolocation sounds like. *play clip*

The dolphin makes a click sound that it sends out in the water. When the click hits an object, it creates an echo, which then travels back toward the dolphin. By listening to the click echoes, the dolphin can then produce a kind of “mental” image of the object. Typically, a dolphin will wait to produce a click until it receives the echo from previous clicks. This means that as the dolphin moves closer to the object, it starts producing clicks more rapidly. You can hear in this audio clip how the clicks seem to speed up – in this case, the dolphin is approaching our camera. *play clip*

Okay, with that information fresh in your mind, have a listen to this clip. *play megapclicks*

This is an audio recording made from a humpback whale, and upon first listen, it sounds an awful lot like the bottlenose dolphin echolocation recording. In order to make this recording, scientists from the Hawaii Institute of Marine Biology, Woods Hole Oceanographic Institution, University of New Hampshire, and NOAA’s National Marine Sanctuary Program placed recording tags on humpback whales . The tags, known as DTAGS, are attached by suction cup to the whale’s back. The tags record the whale’s position and movements, as well as the whale’s vocalizations. The clicks recorded by the tag had two important properties: 1) they were only recorded at night, and 2) they were recorded during feeding episodes. These two observations certainly suggest that these might in fact be echolocation clicks: that is, clicks used by the whale in order to locate and track prey.

There are other clues suggesting that these clicks might be echolocation. Firstly, the click trains (or series of clicks) usually ended in a rapid series of clicks called a buzz. This pattern, called a terminal buzz, has been observed in echolocating odontocete species and usually coincides with the final phase of prey capture. These terminal buzzes were also accompanied by a sharp roll – that is, the animal turned quickly on its side – another behavior associated with prey capture.

To watch a video 3-D model reconstruction of a humpback during one if its feeding dives using Megapclicks, visit the dolphin pod website for links.

Video of Megapclicks from NOAA 

As intriguing and convincing as this all sounds, the scientists involved are very cautious about stating that humpbacks are indeed echolocating. It may be that these click sounds are simply a way for the humpback to herd or startle fish. In order for this to truly be called ‘echolocation’, we would need to know if the humpbacks are actually even able to hear these clicks themselves, let alone if they are able to use the echoes to gain object or environmental information.

At the recent Society for Marine Mammalogy biennial conference in Cape Town , scientists working on Megapclicks presented their findings. After the presentation, someone in the audience asked if the scientists had considered the idea that these click sounds might in fact be a form of communication, or more precisely, part of the humpback’s song repertoire. Humpbacks are famous for producing elaborate songs , and, according to this expert, these Megapclicks apparently resemble one of the song elements.

This discovery highlights the fact that scientists still know so very little about the behavior of whales and dolphins. Only a few decades ago, we did not even know that dolphins had a sense of echolocation; although today, we understand it to be a fundamental aspect of their behavior, biology, physiology and evolution. Whatever Megapclicks are – whether echolocation or a simple vocalization – they will be keeping scientists busy for years to come.

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Kids' Science Quickie

Pelorus Jack

Pelorus Jack was a Risso’s dolphin who was famous for helping guide ships through a dangerous stretch of water in New Zealand known as French Pass. The legend of Pelorus Jack states that, back in the late 1800’s, Jack would appear whenever a ship approached the straight, and would help guide the ship through the treacherous rocks and currents into Pelorus harbor. Legend tells that a drunken passenger on a steamboat called Penguin once shot Jack with a rifle. After that, Jack would never appear to help guide the Penguin into harbor, although he still helped other ships. Ironically, the Penguin was wrecked years later while trying to navigate French Pass without Jack’s help. No ship ever wrecked in the pass when Jack was there to guide them. Jack was spotted regularly for over 25 years before disappearing in 1912 – presumably having died of old age. What do you think about the legend of Pelorus Jack – is his story science fact or science fiction? Do you really think he helped guide ships into the harbor? To learn more about the legend of Pelorus Jack and to conduct your own investigation, visit the dolphin pod website for links.

The Legend of Pelorus Jack

Pelorus Jack on Wikipedia

Pelorus Jack Encyclopedia of New Zealand entry 

 

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Dolphin Quiz

How do Risso's dolphins get white scratches?

Last show’s winner was Izzy who correctly stated that a “wholphin” is a hybrid cross between a false killer whale and a bottlenose dolphin. Now, for this week’s quiz: where do the white scratches seen on the skin of Risso’s dolphins come from? Think you know the answer?  Winners will randomly be chosen from the correct answers, and will be announced on next week’s show. 

Risso's Dolphin

Image from David Hofman's website 

 


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Wrap-up:

That’s it for this week’s edition of The Dolphin Pod – thanks for tuning in. If you would like more information about the stories from this week’s episode, check out thedolphinpod.com. If you’ve got questions or comments about this week’s podcast episode, please contact us through the website. Why not consider signing up for the Dolphin Communication Project’s online community? You’ get access to a forum where you can discuss the The Dolphin Pod with other listeners. The DCP website offers a chance to adopt one of our dolphins from the Bahamas, as well as learn more about volunteer, internship and ecotour opportunities.

Don’t forget to join us next week for more dolphin science news and info. And remember, the dolphin pod is only a click away.

Tagged under
Amazon River Dolphin, Dolphin Color, Dolphin News  (Episode 4)
13 December 2019

Amazon River Dolphin, Dolphin Color, Dolphin News (Episode 4)

 
In this week’s episode, we will  discuss how you can help conserve dolphin species,  review breaking Dolphin News from around the world, focus our Science Spotlight on the Amazon River dolphin, and in our Kids’ Science Quickie,  we’ll discuss colorful dolphins.
 
 
DolphinPod News

Cambodia conservation, Scottish jet skier fined, New Zealand conservation delay

Cambodia launches plan to save the endangered Irrawaddy dolphin. The Mekong River in Cambodia is home to approximately 100 Irrawaddy river dolphins – a critically endangered river dolphin species. The largest threat to this species is fishing, which leads to either accidental entanglements, or depleted food resources for the dolphin. In an effort to reduce human impact, the Cambodia government is launching a program to encourage tourists to the area to view the dolphins.  The program will help decrease use of the river for food by promoting alternative food sources for local villagers, as well as boost the local economy by developing local dolphin-watching tourism. 

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A man in Scotland has been fined for harassing dolphins while jet skiing. Believed to be the first successful prosecution of its kind, the jet skier was fined 500 Pounds for recklessly harassing a group of dolphins near Moray Firth in June of 2006.  Moray Firth in Scotland is home to a resident population of approximately 130 bottlenose dolphins. Dave MacKinnon, a wildlife crime officer for Grampian Police, told the BBC that “this incident will send a strong message to people who use the marine environment for their work and leisure. What we ask is that people using such crafts do so in a responsible manner for their safety and that of others including protected wildlife.”

 

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The New Zealand government has delayed a decision on protective measures for the endangered Maui’s and Hector’s dolphins. The government is reviewing a threat management plan calling for set-netting and trawling to be prohibited within two nautical miles of the Te Wae Wae Bay shore in order to protect Hector’s and Maui’s dolphins from possible entanglement. WWF-New Zealand released a statement saying “We are deeply concerned that the Government is delaying protecting our dolphins.  The decision means that more dolphins will die in fishing nets this summer.” New Zealand Fisheries Minister Jim Anderton and Conservation Minister Steve Chadwick announced that because of the huge number of submissions on the proposed plan, a decision would not be made until March of 2008.


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Science Spotlight

Amazon river dolphin object carrying displays

The Amazon river dolphin, otherwise known as the boto, is a freshwater river dolphin found in Southern America. The boto is often referred to as the ‘pink dolphin’, although not all individuals are pink. In fact, DCP learned this week at the Society for Marine Mammalogy’s Biennial conference that it is only the male botos that obtain a pink color, and that this is because of an accumulation of scar tissue.  The boto’s natural color is a bluish gray. Male botos engage in aggressive biting matches, which scar their skin, causing bright pink patches to appear. After a lifetime of bites, their whole bodies take on a pinkish color; a testament to a life of aggressive encounters with other males. Botos also have pronounced sexual dimorphism: the males are quite a bit larger than the females. Males can be two and a half meters in length, whereas the females only reach about 1.8 meters. It seems that male botos are special in many ways, and not just when it comes to size and appearance. It now appears that male botos are the only species other than man and chimpanzees that carry objects in order to impress females or intimidate other males. Chimpanzees are known to brandish objects like branches or big sticks in order to show off to other males and females; human males have a huge assortment of bling that we use for similar purposes; but the male boto makes his presence known by carrying rocks, clay and weeds.

Botos had often been observed playing with object found in their environment, and scientists used to think this is exactly what it was: playing. But boto expert Dr. Anthony Martin of the Sea Mammal Research Unit at the University of St. Andrews presented a paper at the Society for Marine Mammalogy biennial conference wherein some important discoveries were presented about this object carrying behavior to suggest that it is not play behavior at all. Over the course of three years, Anthony and his colleagues made 221 observations of botos carrying objects. The dolphins would typically grip the objects in their mouths and sometimes thrash about at the surface while holding the object aloft, or rise up vertically while holding the object before sinking back down again. For the 221 observations, it was found that it was almost exclusively adult and sub-adult males who brandished these objects. The carrying behavior was most often recorded in large groups of males. In groups where object carrying was observed, aggressive behavior was 40 times more likely to be recorded. These two facts suggest that these carrying bouts are in fact aggressive displays put on by males, possibly to intimidate other males. Object carrying was also observed at times of the year most closely associated with female fertility, another clue that this is likely socio-sexual behavior and not play.

Boto object carrying behavior made a brief appearance in the 2006 BBC series Planet Earth hosted by Sir David Attenborough. In the episode called “Fresh Water”, we see a male boto thrashing about a piece of seaweed. Although the documentary claims that a successful object carrying bout leads to mating attempts, Anthony points out that his research team has never once observed any mating behavior by the boto. Genetic evidence, however, does suggest that the males who carry the most objects do end up fathering the most calves, so Planet Earth is probably not too far off the mark.

The boto now joins the ranks of the Indo-Pacific Bottlenose dolphin and the Indo-Pacific humpback dolphin as the only three dolphin species having been observed using objects in their environments. For the boto, the objects are involved in a socio-sexual display, whereas the other two species appear to use sponges as a kind of foraging tool. It could well be that boto object carrying is another potential sign of culture in dolphins: a skill that is passed down from generation to generation. Whether culture or not, the boto’s object carrying is certainly a one-of-a-kind behavior and is very exciting news for dolphin scientists.

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Kids' Science Quickie

Dolphin colors

Dolphins come in many different colors. Some dolphins, like the killer whale, have dramatic black and white patches, whereas bottlenose dolphins are a soft gray color. If you take a look at images of various dolphin species, you will notice a trend that is true for most all species: the belly of a dolphin is usually a light color whereas a dolphin’s back is usually a darker color. Even bottlenose dolphins are not the same shade of gray all over – their bellies are much lighter. This kind of color pattern is seen in many animal species and is known as counter-shading. For animals living in the ocean, counter-shading is a kind of camouflage that helps them blend in and avoid detection. If you look down on a dolphin from above in the water, its dark coloring will help it to blend into the dark deeper waters or ocean bottom. But seen from below, the dolphin’s lighter belly helps it to blend into the bright sky or ocean surface. Many species of shark and fish have counter-shading as well. Penguins are another great example of an aquatic animal that uses counter-shading: their bellies are bright white but their backs are black. Counter-shading is a simple and effective form of camouflage, but it won’t keep you hidden well enough to avoid a penguin hug … *happy feet clip*

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Dolphin Quiz

What is a wholphin?

Last show’s winner was B. Bowman who correctly stated that MLDB stands for monkey lips/dorsal bursae. Now, for this week’s quiz: what is a wolphin? Think you know the answer?  Winners will randomly be chosen from the correct answers, and will be announced on next week’s show. 


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Feature


It's the year if the dolphin - again!

2007 has been designated The Year of the Dolphin. In an earlier episode of The Dolphin Pod, we discussed the origin of the Year of the Dolphin as a United Nation’s initiative. Now that we are in the last month of 2007, you might think it is time to say goodbye to the Year of the Dolphin. Well there is some great news for all you dolphin fans out there: the Year of the Dolphin has been extended into 2008! Bolstered by the great success of the campaign, the Convention on Migratory Species (or CMS) and its partners including the Whale and Dolphin Conservation Society, are extending the initiative through 2008 in order to ensure continued support for programs that help conserve marine mammals and their environments and ecosystems around the world. Robert Hepworth, Executive Secretary of CMS said in September when the announcement was made: “YoD is gathering momentum and we have officially endorsed a variety of activities in 30 countries since the campaign began in January 2007. We are still receiving new offers to support the campaign and publicize it around the world, most recently through a special event in Panama on 27 August targeted at Latin America. The Partners decided we should carry on the campaign into 2008 to give more individuals, organizations and countries the chance to participate in the Year of the Dolphin”.

As part of the campaign, the United Nations Environment Programme is helping to release an IMAX documentary focusing on marine mammals in 2008. Titled DOLPHINS & WHALES 3D: Tribes of the Ocean, the film is presented by Jean-Michel Cousteau – son of famed ocean explorer and documentary-maker Jacques-Yves Cousteau. The documentary features stunning images of whales, dolphins and other marine creatures shot in 3D, and is slated for release in February, 2008.

So what can you do to celebrate the year of the dolphin? Here are 5 simple things that will help make a difference:

1)      Sign an online petition focused on whale and dolphin conservation

2)      Support nonprofit organizations like DCP in their science, education and conservation efforts

3)      Participate in environmentally responsible dolphin and whale watching ecotours

4)      Only eat fish and other seafood that comes from sustainable and eco-friendly sources

5)      Educate yourself about the threats that dolphins face – and then start educating those around you

 

Even in light of the many conservation-based programs to protect dolphins, 2007 was also a sad year for dolphin conservation as it marked the year in which the Baiji – or Yangtze river dolphin – went functionally extinct. The bad news is that human activity is the reason why whale and dolphin species are threatened or endangered. The good news is that, with some initiative, humans can also ensure that the Baiji is the last cetacean species that we ever let go extinct. Why not follow our 5 steps for celebrating the Year of the Dolphin, and visit the Year of the Dolphin website to learn how you can become part of the solution.

 

Wrap-up:
That’s it for this week’s edition of The Dolphin Pod – thanks for tuning in. If you would like more information about the stories from this week’s episode, check out thedolphinpod.com. If you’ve got questions or comments about this week’s podcast episode, please contact us through the website. Why not consider signing up for the Dolphin Communication Project’s online community? You’ get access to a forum where you can discuss the The Dolphin Pod with other listeners. The DCP website offers a chance to adopt one of our dolphins from the Bahamas, as well as learn more about volunteer, internship and ecotour opportunities.

Don’t forget to join us next week for more dolphin science news and info. And remember, the dolphin pod is only a click away.

Tagged under
Dolphin Buoyancy, Dolphin Hair, Dolphin News (Episode 3)
13 December 2019

Dolphin Buoyancy, Dolphin Hair, Dolphin News (Episode 3)

In this week’s episode, we will discuss whale and dolphin watching with biologist Fabian Ritter, review breaking Dolphin News from around the world, focus our Science Spotlight on dolphin buoyancy, and in our Kids’ Science Quickie,  we’ll discuss hairy dolphins.

DolphinPod News

 

Mysterious dolphin deaths in Australia, Hayden Panettiere arrest warrant


A rash of dolphin deaths in Australia has biologists baffled. Sky News is reporting that nine bottlenosed dolphins have been found dead on the shores of the popular tourist area of Gippsland Lakes in Australia within the past 12 months. Researchers are unsure as to what is causing these deaths. One theory is that they are ingesting toxic chemicals which may be coming from local industry or blue-green algae blooms in the area.

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An arrest warrant has been issued for Hayden Panettiere after her clash with Japanese fisherman . Hayden, star of the hit TV series Heroes, was involved in a highly-publicized protest against the annual dolphin drive hunts in Taiji Japan. This week she told E! News "I learned today that I have an arrest warrant out for me in Japan because of what I did for Save the Whales,".  Hayden stated that she was thrilled that her protest is receiving international attention.


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Science Spotlight

Do dolphins float or sink?

Last week’s dolphin quiz asked the question : if a dolphin stops swimming and remains motionless, will it float or sink? The answer is quite simple: it all depends.  

A whole list of factors will cause a dolphin to sink or swim in water, including how much air it has in its body, the amount of blubber it has, and perhaps most importantly, how deep it is in the water. Whether or not an animal floats or sinks in water is a direct result of something called buoyancy. The principle of buoyancy was initially discovered by the famous Greek mathematician Archimedes, who was born in 287 BC. It works like this: when you submerge an object in water, the object will displace a volume of water equal to its own volume. Now, if the water that has been displaced has the exact same mass as the object, the object will stay in one place. But, if the object has less mass than the water that has been displaced, the object will float. The denser water will actually push the object up to the surface.  If on the other hand the object has more mass than the displaced water, it will sink. Mass will be determined by the material that the object is made of.  If you have an object made up of a very dense material, like steel, then that object will most certainly sink, whereas less dense material, like air, will float.

A dolphin’s body is filled with materials of various densities. Bones, which are denser than muscle. Muscle, which is denser than blubber. But, also air spaces – primarily the lungs. You can total all of these together to get the overall mass of a dolphin. Comparing the dolphin’s mass to the mass of the water that is displaced by the dolphin’s body when submerged will tell you whether or not the dolphin will float or sink. As a general rule, a healthy dolphin with its lungs filled with air will float at the surface: its body has less mass than the seawater it displaces. This is primarily because air is much less dense than seawater, which means a portion of the dolphin’s body volume is filled with a material much less dense than the water around it.

But that’s not the whole story. As a dolphin dives down in the water, another factor comes into play: hydrostatic pressure . This is the weight of the water itself. Water is heavy stuff, and as a dolphin starts to dive under water the increasing weight of the water on top of it will start to affects its body rather drastically. The hydrostatic pressure will cause the dolphin’s lungs to collapse: the air in a dolphin’s body is actually squeezed into a smaller area. At about 65 or 70 meters down, a dolphin’s lungs will be completely collapsed, and the actual size of a dolphin’s body will shrink. Compared to its size at the surface, the dolphin is now physically smaller – much like a sponge that you can crush in your hand into a tiny ball. But despite all this shrinking, the dolphin’s mass stays the same. Since the dolphin is now displacing less water because it has shrunk, but its mass stays the same, it actually starts to become heaver than the water it displaces the deeper it goes. So now the tables have turned and the dolphin will start to sink instead of float. This is something that all deep diving marine mammals use to their advantage when foraging in deep waters. Many species need to counteract their positive buoyancy at the surface by actively swimming down, but once they reach the magic shrinking point, they can relax and glide deeper down without moving a muscle. Not all species of marine mammals are positively buoyant at the surface: a few species of seals as well as some of the great whales are negatively buoyant at the surface. But dolphin species, as far as I have been able to determine, all appear to be positively buoyant at the surface.

Of course, this positive buoyancy assumes that they have lungs filled with air. When a dolphin or whale dies, the air in its body may disappear or even be replaced by water, causing it to sink. A few species of whale and dolphin (including the right whale and the sperm whale) appear to be positively buoyant even when dead, which causes them to float. As time passes, even the body of a dead whale or dolphin that has sunk to the bottom might actually start to float again as the process of decomposition begins creating gasses in its body that cause it to become positively buoyant.

It has also been noted that buoyancy changes depending on how much fat or blubber an animal has on its body. This may change with the season as some migratory species move from breeding grounds to feeding ground and their eating habits change.

Another factor that affects the buoyancy of dolphins while diving is the temperature of the water. In most of the ocean, the water tends to get colder the deeper you go. Colder water is denser than warm water, which means that as a dolphin starts to dive into deep cold waters, the increased density of the cold water will once again begin increasing the dolphin’s buoyancy.

So as you can see, there is no easy answer to the question ‘does a dolphin sink or swim’.  But who needs easy answers when you can have interesting ones, right?

Reading Resources:

T.M. Williams et al., "Sink or swim: strategies for cost-efficient diving by marine mammals," Science, 288:133-6, April 7, 2000.

Williams, T.M., J.E.Haun and W.A.Friedl. 1999. The diving physiology of bottlenose dolphins (Tursiops truncatus). J. Exp. Bio. 202:2739-2748.

P. L. Tyack, M. Johnson, N. Aguilar de Soto, A. Sturlese and P. T. Madsen, 2006. Extreme diving of beaked whales. The Journal of Experimental Biology, 209: 4238-4253.

Nowacek, D. P., Johnson, M. P., Tyack, P. L., Shorter, K. A., McLellan, W. and Pabst, D. A. (2001). Buoyant balaenids: the ups and downs of buoyancy in right whales. Proc. R. Soc. Lond. B 268,1811 -1816.

 Hooker, S.K., and R.W. Baird. 2001. Diving and ranging behaviour of odontocetes: a methodological review and critique. Mammal Review 31:81-105

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Kids' Science Quickie



Do dolphins have hair?

As you may know, dolphins are mammals . One of the defining characteristics of all mammal species is that they have hair on their bodies. But, what about dolphins? With their smooth streamlined shapes, it doesn’t look like they have any hair at all – do dolphins have hair? In fact, when dolphins are born, you can actually find a few stray hairs poking out of their chin. But soon after birth these hairs will fall out and all you will be able to see are hair follicles which are tiny pockmarks that the hair used to grow out of. Some of the larger whales have hair that stays with them their entire lives. Humpback whales have distinctive bumps on their lower and upper jaw from which tiny hairs protrude.  These hairs may actually help humpback whales to sense things in their environment, much like a cat’s whiskers.  Dolphins don’t really need hair to survive: they can keep themselves warm with a toasty layer of fat under their skin (called blubber). Having no hair on their bodies makes it easier for them to swim in water. This is the same reason that Olympic swimmers tend to shave all the hair off of their bodies.  Less hair equals less drag which means an easier time chasing after fish! Well, for the dolphins anyway… I don’t know if Olympic swimmers spend too much time chasing fish ...

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Dolphin Quiz

What does MLDB stand for?

Last week's winner was Allen McCloud who correctly stated that dolphins are positively buoyant at the surface but negatively buoyant at depth. Now, for this week’s quiz: Concerning a specific part of a dolphin’s anatomy, what does the acronym MLDB stand for? Think you know the answer? Surf on over to thedolphnipod.com and click on Dolphin Quiz – leave your answer in the comments section. Winners will randomly be chosen from the correct answers, and will be announced on next week’s show. 


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Feature

Responsible Whale and Dolphin Watching

According to Fabian Ritter, co-founder of the non-profit research organization M.E.E.R. (Mammals Encounters Education Research) an estimated 12-15 million people go whale and dolphin watching in more than 500 locations worldwide. Whale and dolphin watching tours can be found in over  90 countries on all continents. According to a study conducted in 2000, whale watching has a growth rate of 10-15% per year, with some countries witnessing growth rates of far more than 100% per year.  This makes whale and dolphin watching the fastest growing branch of the tourist industry.

I interviewed Fabian Ritter by email about the whale watching phenomenon, and asked him about MEER’s research on La Gomera. La Gomera is the second smallest island of the Canary Islands – a group of islands located off the north western coast of Africa, and owned by Spain. Whale and dolphin watching is big business in the Canaries , with dozens of species regularly visiting the water around the islands throughout the year. According to the official Canary Islands Web site, it is the second most popular whale watching tourist area in the world, with just shy of 1 million visitors a year coming to see the whales and dolphins.

Around La Gomera, tourists can spot bottlenose dolphins, short-finned pilot whales, Atlantic spotted dolphins and rough-toothed dolphins (all resident species). Striped and common dolphins, beaked whales, baleen and sperm whales, as well as several other species also pop by for regular visits.  In all, over 21 different cetacean species are seen regularly around La Gomera, which (relative to the size of the survey area) represents the highest cetacean species diversity in Europe.

But, a booming whale and dolphin watching industry does not always mean good news for the whales and dolphins involved. According to Fabian, humans can easily disturb cetaceans, primarily when watching from a boat, which is the preferred method for over two thirds of all whale watchers worldwide, or by trying to swim with them. This can cause groups to separate, change their behavior (including longer dive times, changes of swimming speed and direction, etc.), and interfere with their communication skills via engine noise, or by causing collisions, which may injure or even kill animals. These are the short-term effects.

If these short-term effects persist over longer periods of time, long-term effects may be observed (as is the case in several places around the world): Populations may change their behavioral budget, animals may abandon important (critical habitat) areas, noise and physical disturbances lead to stress and thus to a higher susceptibility to disease. This results in a lower reproduction rate and the decrease of population size.

A more indirect effect that whale watching may have is the false impression that the animals are “tourist attractions”, which “serve” humans. However, proper education and well-designed ecotours (in the sense of an education ecotour rather than a “fun trip”) may avoid the creation of such false images in the minds of visitors.

The biggest problem in La Gomera is boat-based whale and dolphin watching, as this has a far greater potential to disrupt cetacean behavior. Loud noises (e.g. fast turning propellers) and high speed boats are likely worse than slow moving boats that ideally have a propeller shrouding to prevent injuries.

Increasingly, swim-with-dolphins and whales tourism has proven potentially disruptive

According to Fabian, certain populations of wild cetaceans are already under serious threat from the whale and dolphin watching industry. David Lusseau working with bottlenose dolphins in New Zealand has found that the small population in Doubtful Sound is threatened to disappear as a consequence of unsustainable tourism practices. Also, Lars Bejder and colleagues found a significant effect on the reproduction rate of female bottlenose dolphins in Shark Bay, Australia .

Fabian suspects that the cetaceans off of Tenerife (another island in the Canary Islands), which probably are the most intensely watched cetaceans in the world (up to 30-35 boats going on 2-3 trips every day, or over 10.000 trips per year) will have difficulties thriving in the long term, although there is no scientific evidence  yet to suggest that long-term damage is occurring.

Currently, there is no universal standard, code of conduct, or regulatory body that oversees whale watching operators worldwide, although there are national regulations for some countries involved in whale and dolphin watching. Fabian suggests that the general attitude should be that humans should adapt our behavior to the needs and habits of the animals; that is so that the animals can avoid having to adapt theirs. And, that whale and dolphin watching tours should be promoted as a way to experience nature and to learn about it, rather than inflicting our desires onto nature. The management of the industry should be pro-active following the principles of sustainability with the establishment of properly enforced legislation dictating a maximum number of operations per area and time unit, a limit to the number of boats, as well as a set of rules of how to behave around the animals, and constant monitoring both of the populations and the effectiveness of the rules/regulations themselves.

Above all else, Fabian feels that common sense, sensitivity and experience are the most important tools to deal with cetaceans in a proper, i.e. sustainable, or better to say respectful way.

 

Wrap-up:
That’s it for this week’s edition of The Dolphin Pod – thanks for tuning in. If you would like more information about the stories from this week’s episode, check out thedolphinpod.com. If you’ve got questions or comments about this week’s podcast episode, please contact us through the website. Why not consider signing up for the Dolphin Communication Project’s online community? You’ get access to a forum where you can discuss the The Dolphin Pod with other listeners. The DCP website offers a chance to adopt one of our dolphins from the Bahamas, as well as learn more about volunteer, internship and ecotour opportunities.

Don’t forget to join us next week for more dolphin science news and info. And remember, the dolphin pod is only a click away.

 

Tagged under
SMM Conference, Spy Hopping, Surfing Dolphins, Dolphin News (Episode 2)
13 December 2019

SMM Conference, Spy Hopping, Surfing Dolphins, Dolphin News (Episode 2)

 
In this week’s episode, we will talk with Dr. Kathleen Dudzinski about the upcoming conference on marine mammalogy in Cape Town, review breaking Dolphin News from around the world , focus our Science Spotlight on a behavior known as Spy Hopping , and in our Kids’ Science Quickie,  we’ll discuss surfing dolphins. 
 
DolphinPod News

Hayden Panettiere in dolphin protest, stranding in Iran, tool use seen again in wild dolphins

Hayden Panettiere , who stars as the indestructible cheerleader Cliare Bennet on the hit TV series Heroes ,  was involved in a dolphin protest in Japan this week . In association with the anti-whaling group Sea Shepherd , Hayden and a group of surfers paddled into a small bay in Taiji Japan, where Japanese fisherman were preparing to slaughter a group of dolphins as part of their annual dolphin drive hunt. After a dramatic confrontation with the fisherman, an emotional Hayden returned to shore unable to prevent the hunt from taking place, and gave a brief interview with Sky News (AUDIO CLIP) . In a statement released last Friday, Hayden discussed her reasons for joining the protest:  She stated: "Because I am in the public eye I feel the need to be a voice of worthy and important causes whose efforts impact the lives of every person on Earth. These animals are being brutally and unnecessarily slaughtered – and who are we to say to they have less of a right to exist than we do."  You can find links to video footage of the incident on The Dolphin Pod website

A mass stranding of striped dolphins in Iran has environmentalists concerned . Over 150 striped dolphins have been found stranded near the southern port of Jask in Iran as part of a mass stranding that began in the end of September. Local Iranian scientists are guessing that the dolphins drowned after becoming entangled in fishing nets. Other possible explanations for the strandings include acute poisoning due to a toxin in the dolphins’ habitat, infectious disease, and exposure to low frequency active sonar used by military organizations. Iranian officials  stated that the cause of the strandings remains a mystery.

Scientists form Australia are reporting a sighting of tool use by a wild Indo-Pacific humpback dolphin . An adult Indo-Pacific humpback dolphin was observed by researchers in Hinchinbrook Channel , in northeast Queensland, Australia, carrying a sponge on its rostrum. Researchers suggest that the dolphin was somehow using the sponge as a tool during foraging. This is the second species of dolphin to be observed using tools in the wild – researchers had initially observed Indo-pacific Bottlenose dolphins using sponges in a similar fashion.


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 Science Spotlight

What is spyhopping?

What is spyhopping? In this week’s Dolphin Pod News, we heard a short audio clip wherein Hayden Panettiere mentions a cetacean behavior known as spy hopping . Describing her encounter with Japanese hunters and a group of pilot whales trapped in the cove, Hayden said: “There was one point when they were literally spy-hopping, which is when they jump out of the water and stick their heads up out of the water and they can look around”. What exactly is spyhopping and why do whales and dolphins do it? Well for once, the answer to this question is as obvious as it seems it should be. Whales and dolphins hold their heads out of the water in order to visually inspect the environment above the water line. Many species of whales and dolphins are known to engage in spy hopping. Perhaps the most prolific spy-hoppers are orca and humpback whales; two species who receive quite a bit of attention from the tourist industry. Spy hopping behavior consist of the cetacean holding itself vertically in the water and kicking with its tail fluke in order to hold its head above the water line. Some individuals are able to keep this up for minutes at a time. It is quite similar to treading water for a human, although likely somewhat more difficult for cetaceans because they are less buoyant in water than we are.

You may recall from an earlier episode of The Dolphin Pod that dolphins and whales have eyeballs that are specially designed for underwater vision. Whales and dolphins evolved from land animals many millions of years ago, and their eyeballs had to evolve in order to adjust to permanent underwater living. But the changes in their eyeballs were remarkable in that, despite their ability to see quite well underwater, both dolphins and whales have retained excellent vision in air. Although perhaps ‘retained’ is not the correct term; in order for a dolphin’s eyeball to have evolved the ability to see equally as well in water as in air, new anatomical structures were required.

 

These include a rounded fish-eye like form to the eyeball together with a highly mobile lens that is capable of dramatically changing position. The end result of all this fancy evolution is that, when a dolphin or whale engages in spy hopping behavior, it is able to see almost as well as you or I can at the surface.

Scientists have observed that spyhopping occurs frequently when dolphins or whales interact with tourist boats. It is simply a case of that they wish to see what all the fuss is about at the surface, and the best way to do this is to hold your head out of the water. Echolocation is entirely ineffective in air. The difference in density between air and water means that any echolocation directed at the surface will be completely useless – all of the sound waves will bounce off of the surface, making it impossible for a whale or dolphin to tell what is going on without sneaking a peak. Spyhopping is seen frequently around Vancouver Island in British Columbia – where groups of tourist in whale watching vessels flock to see the largest dolphin of all: the orca.  The vast majority of objects and phenomena that a dolphin or whale needs to know about can be found under the water. But humans, in our strange surface-skimming boats, present a curious new object to whales and dolphins; an object that must be inspected both above and below the water’s surface to be fully appreciated.

But spyhopping is only one of the many cetacean behaviors that take place ‘at the surface’.  Aside from breaking the surface to breath and spyhop, whales and dolphins are known to lunge out of the water, and to porpoise – a behavior where they arc out of the water but remain mostly horizontal while travelling at speed; presumably to reduce drag when in a hurry. They also engage in a variety of behaviors that fall under the umbrella of ‘breaching ’. Breaching can take many forms, from shallow side-flops, to high jumps many meters above the water’s surface. In the case of spinner dolphins or dusky dolphins, these breaches and jumps can be accompanied by crazy spins or other twists and turns, forming complex aerial displays. Scientist are still puzzled as to the meaning of the various forms of breaching. Different forms of breaching and jumping may be used as visual communicative signals, as means of orientation, as social signals associated with play, fighting or courtship, as a means of stunning fish, in order to create a loud sounds used in communication, or as a way to remove parasites.  Spyhopping on the other hands appears to be a very simple behavior with an obvious goal; to see what’s going on

 
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Kids' Science Quickie

Surfing dolphins

Surf’s up dude! Humans aren’t the only animal that likes to catch a wave every now and then. Even though they don’t use surf boards, dolphins love to go surfing! Just like human body surfers, dolphins have been known to ride the crests of big waves as they roll into shore. Just before the wave will crash into shore, the dolphins will turn around and rush back into open water. They can even be seen leaping clear out of the water from the top of a wave. The waves and the currents that they create help to push the dolphins along in the water, allowing them to attain fast swimming speeds with minimal effort. This is similar to the way that newborn dolphin calves stick close to their mother’s side in order to help them swim.  As a mother dolphin swims quickly through the water, she forms something called a ‘slipstream’ next to her body as the water rushes past her. If the baby dolphin is inside this slipstream, he or she will be carried along with mom.

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Dolphin Quiz

Do dolphins float or sink?

The winner of last week’s quiz is Brianna Bowman, who correctly stated that the Median Notch is the indentation between the two flukes of a dolphin’s tail.

Now for this week’s quiz:  if a dolphin stops swimming g and remains motionless, will it float or sink?

Think you know the answer? Surf on over to thedolphnipod.com and click on Dolphin Quiz – leave your answer in the comments section. Winners will randomly be chosen from the correct answers, and will be announced on next week’s show. 

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Feature

Getting Ready For The Biennial Conference on the Biology of Marine Mammal

The Biennial Conference on the Biology of Marine Mammals is a gathering of marine mammalogists and other scientists from around the world. This year the 17th Biennial conference will be held in Cape Town, South Africa, from November 29 - December 3, 2007.  The conference is put on by the Society for Marine Mammalogy , and may just be the largest gathering of marine mammal scientist in the world.  What follows is my interview with Dr. Kathleen Dudzinski about the conference.

INTERVIEW HERE

 

Wrap-up:
That’s it for this week’s edition of The Dolphin Pod – thanks for tuning in. If you would like more information about the stories from this week’s episode, check out thedolphinpod.com. If you’ve got questions or comments about this week’s podcast episode, please contact us through the website. Why not consider signing up for the Dolphin Communication Project’s online community? You’ get access to a forum where you can discuss the The Dolphin Pod with other listeners. The DCP website offers a chance to adopt one of our dolphins from the Bahamas, as well as learn more about volunteer, internship and ecotour opportunities.

Don’t forget to join us next week for more dolphin science news and info. And remember, the dolphin pod is only a click away.

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Top 5 Dolphin Myths, Ben Underwood, Dolphin News (Episode 1)
13 December 2019

Top 5 Dolphin Myths, Ben Underwood, Dolphin News (Episode 1)

This is our first episode for the new and improved version of The Dolphin Pod.  In this week’s episode, we will unveil the new dolphin pod format, review breaking Dolphin News from around the world, focus our Science Spotlight on the top 5 myths about dolphins, and in our new Kids’ Science Quickie,introduce you to a blind teenager who uses echolocation like a dolphin in order to navigate his surroundings.

 

The Dolphin Pod has been relaunched
The Dolphin Pod has officially moved to our new home on the Dolphin Communication Project’s Web site. In addition to our slick new look on the web, the format and content of our podcast has been expanded and updated. In addition to our feature story, each weekly episode will now include Dolphin Pod News Highlights – a rundown of important news items from around the world featuring dolphins, dolphin science and dolphin conservation. In addition, our Science Spotlight segment will take an in depth look at a specific dolphin-related science topic each week, similar to the kinds of topics we have been exploring in past episodes of The Dolphin Pod. Our brand new Kids’ Science Quickie segment will feature an eye-catching and entertaining news story told in just 60 seconds that will appeal to our younger listeners. And for the trivia junkies out there, each episode will feature a Dolphin Quiz.

Listeners are encouraged to leave comments and ask questions by visiting our new website. Visit www.dolphincommunicationproject.org and navigate over to The Dolphin Pod. Each week’s podcast episode will be available in it’s entirely on the web, or you can listen to the various segments individually. You can also find specific topics that interest you by searching items that are tagged with keywords.
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DolphinPod News

 



Prosthetic tail, Baiji sighting, friendly dolphin injured

A lone Baiji may have been sighted in the Yangtze River. The Baiji is a freshwater dolphin species decaled functionally extinct earlier this year.  In September, Reuters reported that a Chinese fisherman may have seen and even videotaped a Baiji. Even if this sighting can be confirmed however, it will not change the status of this extinct species; a lone Baiji or even just a few Baiji will not be enough to bring the population back to sustainable numbers.

An injured dolphin in Clearwater Florida will be getting a prosthetic tail. According to All Headline News, Winter, an 18 month old bottlenose dolphin now residing at Clearwater Marine Aquarium in Florida, will be receiving a specially designed prosthetic tail. Winter was found entangled in a crab trap in 2005, and her badly inured tail needed to be amputated in order to save her life.

The new tail is helping her to swim and even jump. A similar prosthetic tail was fitted to Fuji – a dolphin residing at an aquarium in Okinawa Japan.

The Whale and Dolphin Conservation Society reports that Dave, a friendly dolphin sighted frequently off the cost of Kent in England, has been seriously injured after an accidental encounter with a boat propeller
. It is not yet know if she will survive her injuries. Like other solitary dolphins who regularly interact with human swimmers and boaters, Dave was at risk of injury from this unusual form of human-dolphin interaction. In 2006, two other friendly dolphins frequently seen in the UK coastal waters died of injuries possibly related to human interaction.
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Science Spotlight

Top 5 Dolphin Myths Dispelled


In this week’s science spotlight, we thought we would take a moment to dispel a few common dolphin myths.  Given the popularity that dolphins enjoy, it is certainly understandable that at least some of the information available in the media, the internet and from the minds of our fellow human beings is not always scientifically sound. Here are 5 commonly heard myths concerning dolphins: Number 1) Dolphins have the best hearing of any animal I actually heard this one just last night on an episode of Ugly Betty. Ignacio suggests that Hilda ‘has the ears of whatever animal hears best’. ‘A dolphin’ chimes in Betty. Unfortunately for Betty, there is little scientific evidence to back up this claim. To begin with, how should we define good hearing? Is it sensitivity to quiet vibrations? If so, dolphins are certainly not anywhere near the top of the list. Many species of snake for example are able to hear the ultra quiet pitter patter of tiny rodent feet from many meters away, to say nothing of the phenomenal vibration sensing abilities of many insects. Perhaps Betty was referring to the ability of dolphins to hear high frequencies? For a large mammal, dolphins certainly do have an impressive ability to hear high frequencies – up to 160 kHz for some species. But other mammals, including echolocating bats, are able to hear up to a staggering 250 kHz. It should also come as no surprise that many species of moths, particularly those hunted by bats using high frequencies, are also able to hear as high as 250kHz. And some animals, like elephants, regularly communicate with sub-sonic frequencies – as low as 1Hz – far below the threshold that humans or dolphins can hear. So no Betty, however you spin it, dolphins certainly aren’t the animal that hears the best. Number 2) Dolphins can stun prey with echolocation If you are a regular dolphin pod listener you may remember all the way back to last year when we covered this topic in detail. The hypothesis that dolphins use their killer sonar to immobilize their prey has been around for decades, but a recent article released in August of 2006 provides evidence suggesting that dolphin echolocation is simply not powerful enough to stun fish. The article in fact describes the scientists‘attempts to stun fish using artificial dolphin echolocation, but no matter how hard they turned up the dial, the fish didn’t seem to be the least bit bothered.

Number 3) Dolphins are one of the only animals to have sex for pleasure

This particular myth tends to pop up with regularity in conversation whenever the subject turns to sex. Even the writers at the ever vigilant snopes.com l end credence to this particular myth. The problem here is that volumes could be (and have been) written on the definition of sexual behavior in animals and the description of pleasure. It isn’t enough to simply go by the dictum that animals have sex to reproduce and therefore any sexual act occurring at times when egg fertilization is impossible must then be understood as occurring for reasons other than reproduction. The truth here is that animals almost never engage in a sexual act with the specific intent of producing offspring; during ovulation or otherwise. It is more accurate to state that animals (including humans and dolphins) are often driven to engage in sexual acts because the act itself is rewarding – it stimulates pleasure centers in the brain through the release of endorphins or other pleasure-inducing brain cocktails. The ultimate cause of this behavior is reproduction, but the proximate cause can be any combination of stimuli that happen to be present at the moment; pheromones, visual stimuli, etc. Occasionally these sexual acts occur at times when the female is not fertile, but it’s not a fertility-state that should be the litmus test for sexual pleasure – it should be the pleasure itself. So if you happen to spot two dung beetles engaged in a lengthy sexual act, you should still be able to state they these beetles are making whoopee for the sheer pleasure of the act itself. Who’s to say dung beetles don’t enjoy sex as much as humans do? Furthermore, what you and I might call a sexual act might be nothing of the kind for an animal like a dolphin. Dolphins often engage in forceful mounting behaviors involving erections that clearly do not involve reproduction, and in fact look more like social dominance or simple aggression. Is it fair to label this as sex for pleasure? Not really. It seems that the scope of the problem here is far too great to simply be summed up in a simple statement to the effect that dolphins engage in sex for pleasure and other animals do not. If it were this simple, we should all have great difficulty explaining why the neighbor’s poodle habitually mounts your leg whenever you pop over for a visit.

Number 4) You will never find sharks where you find dolphins

Sharks and dolphins are not friends. That is not a secret. The wild dolphins that we study in the Bahamas and Japan are covered in bite marks attesting to a lifetime of close-calls involving hungry sharks. Young calves are especially vulnerable to shark attacks, with many newborns not surviving their first year. Dolphins, like many other animals in the ocean, are constantly on the lookout for sharks, and they are doing their utmost to avoid any potentially lethal encounters. But it would be unwise to assume that the presence of dolphins means that they have managed to elude all sharks in the area, and that it is safe to go in the water.  After all, if dolphins were able to avoid shark attacks 100% of the time, why are so many of them covered in shark bites?

Number 5) Dolphins have their own language

This particular topic was covered at length in a previous podcast episode titled Do Dolphins Have a Language? The short and sweet answer to this question is No – they don’t have a language. For the long and equally as sweet answer, check out the episode.
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Kids' Science Quickie

Ben Underwood, the Boy who can Echolocate


Ben Underwood is a teenager living in Sacramento California, and has been completely blind since the age of three. But that doesn’t stop Ben from roller skating, riding a bicycle, or playing basketball. Ben once said that he isn’t really blind – he just can’t see. He may not have use of his eyes, but he is able to paint a picture of the world around him using sound. Ben uses his own special form of echolocation; by making clicking sounds with his tongue, Ben bounces sounds off of objects and listens to the echoes they create. Using this technique, he can hear things like chairs, tables, walls and more, allowing him to walk around the house and outdoors without any trouble at all. This is exactly how dolphins find their way around in the water – dolphins also make click sounds that bounce off of rocks or fish, helping them to hunt and to navigate their environment. To learn more about Ben and his amazing echolocation ability, visit thedolphinpod.com where we have posted a video of Ben. Or visit his website at benunderwood.com ************************

Dolphin Quiz

Median Notch
This week’s dolphin quiz focuses on dolphin anatomy. Which part of a dolphin’s body contains an anatomic feature know as the Median Notch? Think you know the answer? Surf on over to thedolphnipod.com and click on Dolphin Quiz – leave your answer in the comments section. Winners will randomly be chosen from the correct answers, and will be announced on next week’s show. 

Wrap-up:
That’s it for this week’s edition of The Dolphin Pod – thanks for tuning in. If you would like more information about the stories from this week’s episode, check out thedolphinpod.com.  If you’ve got questions or comments about this week’s podcast episode, please contact us through the website. Why not consider signing up for the Dolphin Communication Project’s online community? You’ get access to a forum where you can discuss the The Dolphin Pod with other listeners. The DCP website offers a chance to adopt one of our dolphins from the Bahamas, as well as learn more about volunteer, internship and ecotour opportunities.

Don’t forget to join us next week for more dolphin science news and info. And remember, the dolphin pod is only a click away.

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The Inaugural Episode
13 December 2019

The Inaugural Episode

 

This is the very first episode of our innovative science podcast dedicated exclusively to all things dolphin. The Dolphin Pod will bring you up-to-date and scientifically accurate information on dolphin behavior, cognition, communication, anatomy; you name it, and we'll talk about it. We will also, on occasion, cover dolphin events in the news, summarize and explain the results from recent studies on dolphins and interview scientists currently working on dolphin-related research projects. A special series of episodes will be recorded live from the field, where we will get up close and personal with dolphins in their natural environment, and the researchers studying them. Of course, we will be chatting with the researchers, and not the dolphins. Sorry! In the next few episodes, we will learn why the killer whale is called a whale even though it is actually a dolphin, why this famous dolphin sound {play sound} is probably the worst example of a normal dolphin sound that you can find, and why even your dog would be impressed with the ultrasonic hearing and sound production ability of dolphins. Thank you for subscribing to The Dolphin Pod; we hope you enjoy it. On behalf of all of us; welcome to the pod!

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The Hollywood Dolphin Squeak
13 December 2019

The Hollywood Dolphin Squeak

Learn why the most famous dolphin squeak of all is actually a fraud. This episode looks at one of the most recognizable and famous dolphins sound of all time, and gives an in depth explanation as to why it may not really be a very good example of a dolphin sound at all.

You may recognize this sound [play sound] - it is the ever-popular and greatly over-used dolphin squeak sound that is played whenever a dolphin makes an onscreen appearance for TV or in the movies. But, there is something fundamentally wrong with this sound. True, it was most likely recorded from a real live dolphin, but it is certainly not a typical dolphin sound. Here's why: dolphins spend their entire lives under water - that's an amazing place to be if you want to use sound as a form of communication. The speed of sound in water is around 1482 m/s approximately or 4.5 faster than the speed of sound in air: 331.5 m/s. Not only does sound travel faster in water, but it can travel farther. If it is loud enough and at the right frequency, and if the water conditions (like temperature and salinity) are just right, a sound may travel for thousands of kilometers. Given the ideal conditions that an undersea environment provides for sound transmission, it is no surprise that dolphins have evolved to be very vocal animals. Dolphins make a huge variety of sounds underwater, but they can be more or less put into two different categories: whistle; which are frequency-modulated pure tone sounds, and pulsed sounds; that sound like clicks, creaks, or rusty hinges. Generally, whistles are used for communication, and the pulsed sounds are used for echolocation, or dolphin sonar. This isn't always true, however.

Some click sounds are used for social communication. For example: rapidly-produced, high-intensity clicks called squawks are thought to be used during aggressive encounters - dolphins appear to hit each other with a burst of loud click sounds as a means of hurting their opponent. Kind of like a wild west shoot out, but with sound-waves instead of six-shooters. So what is so wrong with that famous (or perhaps infamous) squeak sound we heard at the beginning of this episode? [play sound] Well, that sound was produced in air, not under water. And that is something that dolphins never usually do. The overplayed Hollywood squeak sound that we are all so familiar with was likely produced for the benefit of human listeners, and is in no way a normal part a dolphin's natural communication system. Hmm - it seems that dolphins are much more adept at altering their own communication system to communicate with humans that the other way around.

Learn more about the sounds that dolphins and other marine animals make: Discovery of Sound in the Sea

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Stunning New Research
13 December 2019

Stunning New Research

A special research news update – the hypothesis that dolphins can use loud bangs or deafening click sounds to debilitate, stun or even kill their prey has been kicking around the scientific world since the 1980s. Learn how new research reveals that this Killer Dolphin Sonar hypothesis is not all that it’s cracked up to be.

Can dolphins kill or stun prey with loud sounds? It certainly seems that way if you believe following headlines: Dolphins' killer sonar confirmed from ABC Science Online February 2001. Killer clicks from New Scientist 1 January 2001. These are, of course, thrilling headlines and far more interesting than the contents of the research papers that they describe. Why quote the following tedious academic prose: "The propagation of click echoes vis-a-vis the contours and composition of the ensonified object must also be considered when conceptualizing efficacious listening positions" When you can say Mysterious monsters are killing fish with murderous death beams as appeared in The Santa Cruz County Sentinel. However, sometimes reality can indeed live up to the hype - 'stunning prey with a blast of sound' is something that happens every day in the ocean. The diminutive snapping shrimp is capable of producing a 200 dB blast using its specially designed claw, rendering unconscious any unsuspecting prey that happen to be passing by. But, can dolphins do something similar? The hypothesis that dolphins can use loud bangs or deafening click sounds to debilitate, stun or even kill their prey has been kicking around the scientific world since the 1980s. It is known as the 'acoustic prey debilitation' hypothesis, and was first introduced in a popular article by Ken Norris and Bertel Mohl that appeared in The American Naturalist in 1983. This hypothesis addressed the question of how sperm whales, with their flimsy looking jaws, were able to capture and eat the fearsome giant squid that kept turning up in their stomachs. These squid typically had no teeth marks on them at all, which begs the question; how did these whales manage to catch and then swallow an entire giant squid seemingly without a struggle? One possible explanation was that they used loud sounds to debilitate the squid so they could slurp them up without a fight. This hypothesis became very popular with the media (as we have seen), but actual real live scientific evidence to support it was strikingly absent for decades. Nobody had ever actually seen a sperm whale or dolphin do anything like this! 20 years later or so, a group of scientists led by Ken Marten published an article in the journal Aquatic Mammals detailing some initial evidence that dolphins might be making a variety of sounds to stun their prey before gobbling them up.

But, conclusive proof was still lacking. However, new evidence from a paper just published in August 2006 in the Journal of the Acoustical Society of America provides some rather convincing evidence that seems to blow the acoustic prey debilitation hypothesis (also known as the prey stunning hypothesis) out of the water - so to speak. A research team led by Kelly Benoit-Bird performed a series of simple experiments: herring, cod and sea bass - some of the favorite food of dolphins - were placed in water tanks with video cameras recording their every movement. Click sounds recorded from real dolphins; both orcas and bottlenose dolphins, were played back to the fish at varying intensity levels and repetition rates. The result: no matter what the researchers threw at them, the fish didn't seem in the least bit bothered by all the fuss. Even with clicks being played back at the highest volume that dolphins are capable of producing, the fish didn't even flinch. It seems that dolphin sounds simply don't have the oomph to rightfully be called a 'killer licks. Is this the final chapter in the 'killer sonar' book? Probably not. Although this latest paper seems to prove that dolphins can not stun or kill their prey with sound, you never know when someone will dig up new evidence to prove that they can. That's the beauty of science! It isn't the nail in the coffin just yet, but it is certainly seems that Killer Clicks are not all that they're cracked up to be.

The classical music clip used in this episode is performed byTwo Violins © 2005: Two Violins
You can read about this new study on the website of The Acoustical Society of America: Click here for the abstract of this new paper

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So high it Hertz
13 December 2019

So high it Hertz

Just how well can dolphins hear? You may be aware that dogs have a hearing range well above that of human beings; they are capable of hearing high frequencies that humans simply are not able to hear. But, did you know that dolphins have a hearing range that far exceeds that of humans and even dogs? Learn more about the ultrasonic hearing abilities of dolphins in this week’s episode.

You may be aware that dogs have a hearing range well above that of human beings - they are capable of hearing high frequencies that humans simply are not able to hear. But, did you know that dolphins have a hearing range that far exceeds that of humans and even dogs? In fact, dolphins are able to hear, and to produce, some of the highest frequency sounds of all mammals. Let's put this into perspective. Humans have a hearing range of around 20 Hz to 20kHz. (that is, 20,000Hz) The Hertz scale is a measure of how many times a second a sound wave is produced.. Here is an example of a 60 Hz sound [play sound] - that is, 60 sound wave cycles per second. The human voice produces a range of frequencies when we speak, but the main frequencies are between 500Hz and 2 kHz. Here is an example of a 1 kHz tone [play sound] - a tone that is pretty easy for humans to hear. The top range of human hearing is up around 18 or 20 kHz - depending on your age and gender. As humans get older, we begin to lose our ability to hear these higher frequencies. I will now play an example of a 15kHz tone [play sound]. Did you hear it? If not, it might be an indication that you are getting on in years. Of course, it is possible that your speakers or headphones are not able to produce a tone that high, so for now, let's blame it on the speakers. So what about dogs? Well, dogs are able to hear frequencies more than twice as high as humans - up around an impressive 45 kHz. But dolphins can do even better than that! For the species whose hearing has been researched the most, the bottlenose dolphin, we know that they can hear frequencies as high as 150kHz. Yes, that's right - 150kHz! If a jump from 1 kHz to 10 kHz sounds like this [play sounds], can you imagine how much higher 150kHz must be?

Dolphins use high frequency click sounds as part of their echolocation, producing and listening to sounds in these high frequency ranges. These clicks can sometimes be heard by the human ear because they contain frequencies below 20kHz, but the loudest frequencies produced in a click are up around 120 kHz. These high frequencies help a dolphin to pick out fine detail when is uses its echolocation to investigate an object. There is one other mammal that can best the dolphin when it comes to producing and hearing high frequencies: the bat. Bats can produce and hear frequencies as high as 250kHz! Now that is a frequency response that not even the most expense 5.1 surround sound home cinema would be able to cope with.

Tagged under
Is that a dolphin or a whale
13 December 2019

Is that a dolphin or a whale

This week’s episode features a discussion of the terms whale, dolphin, and porpoise. Did you know that a killer whale, otherwise known as an orca, is actually a dolphin? Orcas are in fact the largest dolphin species in the world today. So, why are they called whales and not killer dolphins? Well, that is a good question, and there is no easy answer. So instead of an easy answer, here is a complicated one.

Did you know that a killer whale, otherwise known as an orca, is actually a dolphin? Orcas are in fact the largest dolphin species in the world today. So, why are they called whales and not killer dolphins? Which, by the way, sounds downright terrifying? Well, that is a good question, and there is no easy answer. So instead of an easy answer, here is a complicated one: There are around 35 species of oceanic dolphin. All of these species can be correctly referred to as dolphins because they are in the scientific family known as delphinidae. Species in this family all have cone shaped teeth, a single blowhole on the top of the head, among other morphological traits that separate them from the other families. What makes this a little confusing is that the common name for many of these dolphin species has the word 'whale' in the name. The killer whale is a fine example. But there are more, including the melon-headed whale, the pygmy killer whale, the false killer whale, the long-finned pilot whale, and the short-finned pilot whale. To complicate the issue even further, all of the species I just listed are sometimes called blackfish, although they are of course not actually fish, and not really whales, but simply dolphins.

You think that is confusing? Try figuring out how the word porpoise fits in. In North America, many people refer to dolphins (the species in the family delphinidae) as porpoises. They may even call a bottlenose dolphin, the most famous dolphin of all, simply a porpoise. This term came about from fisherman who call most dolphin species a porpoise to differentiate between them and the dolphin fish, otherwise known as mahi-mahi. Now the problem is that science recognizes the porpoise as a different kind of animal altogether. There is a scientific family known as phocoenidae that contains 6 species of what are officially known in science as porpoises. So to be scientifically proper, a porpoise is an animal belonging to the phocoenidae family, and the term porpoise should only be used to describe one of those 6 species. Unless of course you are a fisherman and you want to call a melon-headed whale a porpoise, which you might do, even though it is actually a blackfish or officially a dolphin.

But let us return to the first question: what us a whale? Well according to official scientific terminology, there is no such thing as a whale at all. Science does not formally use the standalone word 'whale' to refer to any of the animals found in the scientific order cetacea; that is the order containing all animals commonly referred to as whales, dolphins and porpoises. The term whale is usually used in the common name of the largest of the animals in the order cetacea, including the blue whale, the sperm whale and the beluga whale. That is because the word whale in English was in use for many centuries before scientists came on the scene and tried classify all of the cetaceans, and it was probably applied rather indiscriminately to most large animals seen swimming in the oceans. Nowadays, a scientist might refer to animals like the blue whale (a species with baleen instead of teeth and grooves on their throats) as rorquals, or they might call the Sperm whale by the name Physeter. Because common names often vary from place to place and language to language, the only way to be sure of what animal you are talking about is to use its scientific name. In English, a Killer Whale therefore was probably originally referred to as a whale simply because it is large; it otherwise has very little in common with an animal like the Blue whale. As we now know, science recognizes the Killer Whale as a dolphin because it is in the delphinidae family.

But here is one more snag: there are 5 species of freshwater river dolphins that are NOT in the dolphin family, but in separate families altogether. These river dolphins are nonetheless correctly referred to as dolphins. As you can see, it is not easy to tell a dolphin from a whale. When in doubt, you can always just shout 'hey, look - there's a cetacean! ' Maybe that is cheating, but at least you will be correct! Wouldn't it be easier if we all just spoke Latin?

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The Dim Dolphin Controversy
13 December 2019

The Dim Dolphin Controversy

The subject of this week’s special episode is a controversial article by Professor Paul Manger of Johannesburg’s University of the Witwatersrand concerning the dolphin brain and dolphin intelligence. This article has caused quite a stir in the scientific world and in the media, producing headlines like: “Scientist says dolphins are dimwits”. In an effort to better understand the science behind this controversial viewpoint, The Dolphin Pod interviewed Prof. Manger about his article. In addition, we interviewed Dr. Lori Marino, Senior Lecturer in Neuroscience and Behavioral Biology at Emory University in Atlanta Georgia.

The Dolphin Pod has attempted to provide an unbiased view of this controversial subject by examining the evidence supporting and contradicting Prof. Manger’s hypothesis. This episode is longer than our usual podcasts (stretching to 26 minutes) and contains a fair helping of scientific jargon, which has been explained throughout. The Dolphin Pod wishes to thank Prof. Manger and Dr. Marino for participating in this discussion – they have both been very generous in taking the time to respond to our questions.

Note: to help keep things clear, you will hear a distinctive ‘bleep-bleep’ sound at the beginning and end of a quotation read from the written responses of Prof. Manger or Dr. Marino.

 (FOR A COMPLETE TRANSCRIPT OF THE INTERVIEW SCROLL DOWN TO THE END OF THE PODCAST TRANSCRIPT)

A recent scientific article claiming that dolphins are not as intelligent as previously thought has been seized upon by the media, and has gained much attention in recent weeks. News outlets like MSNBC, YahooNews, the Times of India, and Aljazeera have produced a series of headlines including:

Scientists say dolphins are dimwits
Ignorance is bliss for dolphins
Dumb Dolphins

And my personal favorite:

Dolphins are flippin' idiots

The author of the article in question, Prof. Paul Manger of Johannesburg's University of the Witwatersrand, has fanned the flames of this 'dim dolphin' controversy with his comments to the press. In a widely distributed interview with Reuters' reporter Ed Stoddard, Prof. Manger is quoted as stating:

"You put an animal in a box, even a lab rat or gerbil, and the first thing it wants to do is climb out of it. If you don't put a lid on top of the bowl a goldfish will eventually jump out to enlarge the environment it is living in. But a dolphin will never do that. In the marine parks, the dividers to keep the dolphins apart are only a foot or two above the water between the different pools."

Concerning the trouble that dolphins have with tuna nets, Prof. Manger stated: "If they were really intelligent they would just jump over the net because it doesn't come out of the water"

Both the article itself and these statements have drawn a storm of criticism from the scientific community, and created a buzz of commentary on the internet. One online editorial proclaims: 'Dolphins Dumb - Scientist is Dumber'. But, behind this controversy is a peer-reviewed scientific paper that has not been adequately subjected to detailed discussion in the media. The paper is titled "An examination of cetacean brain structure with a novel hypothesis correlating thermogenesis to the evolution of a big brain". This paper, authored by Prof. Manger appeared in the May, 2006, issue of Biological Reviews of the Cambridge Philosophical Society. Concerning his paper, Prof. Manger told The Dolphin Pod that 'most reporters have taken small sound bites and missed the point'.

In an effort to better understand the science behind this controversial viewpoint, The Dolphin Pod interviewed Prof. Manger about his article. In addition, we interviewed Dr. Lori Marino, Senior Lecturer in Neuroscience and Behavioral Biology at Emory University in Atlanta Georgia. Dr. Marino has published many scientific articles on the evolution of the dolphin brain and dolphin cognition.

If you are interested in reading the questions posed to Prof. Manger and Dr. Marino by The Dolphin Pod, together with their answers, a full transcript of these interviews can be found on The Dolphin Pod website: www.thedolphinpod.com

To get started, let's examine what Prof. Manger's article is all about:

Prof. Manger's novel hypothesis, which he introduces in his article, is that the size of the cetacean brain (that is, the brain of whales, dolphins and porpoises) evolved as a means of regulating temperature, and not for processing information. It is important to point out that this is a novel, controversial hypothesis - scientists generally assume that all animal brains have evolved first and foremost for information processing, and not heat production. But, Prof. Manger hypothesizes that the unique evolutionary history of cetaceans led to the development of a different kind of brain built for a different purpose. Prof. Manger presents many arguments to support his hypothesis, including the following main points:

1) Cetaceans evolved large brains designed for thermogenesis (that is, heat production) because of a decrease in ocean water temperature that coincides with the increase in brain size approximately 30 million years ago.

2) The structure of the cetacean brain appears to be designed for thermogenesis and not information processing, correlating with the well known sleep physiology of cetaceans.

3) The research results claiming that cetaceans (dolphins, in particular) are intelligent are based on unproven assumptions and, in actuality, cetaceans are not particularly intelligent, as intelligent behavior is the result of complex neural processing for which there is no evidence in the brains of cetaceans.

In terms of causing controversy in the scientific world by introducing a new hypothesis, Prof. Manger is in good company - in 1925, Raymond Dart, a former head of the Department of Anatomy (now the School of Anatomical Sciences) at the University of the Witwatersrand where Prof. Manger currently lectures, introduced a novel hypothesis claiming that modern humans evolved from an early African hominid that he termed Australopithecus africanus. At the time, this idea was heavily criticized by Dart's colleagues who would simply not accept that modern humans came from Africa. This hypothesis is of course widely accepted today. Will the same hold true for Prof. Manger's controversial ideas concerning the cetacean brain? Only time will tell. In the meantime, let's look in detail at each of the three arguments presented by Prof. Manger to see what evidence there is to support or contradict them.

First, let's discuss the hypothesis that cetaceans evolved large brains designed for heat production:

The early aquatic ancestors of cetaceans had relatively small brains. However, about 30 million years ago something remarkable happened: cetaceans started to evolve much larger brains, soon reaching the size we see in modern cetaceans. Prof. Manger argues that this sudden increase in brain size is related to a major cooling of the earth's oceans that took place at about the same time that we see large-brained cetaceans cropping up. The brains of cetaceans, argues Manger, likely grew larger in order for these animals to stay warm in the cooler waters. According to this hypothesis, cetacean brains have a large cerebral cortex with an abundance of heat generating cells that the brain uses to keep warm while awake and, more importantly, while asleep. For most mammals, when we go to sleep, our body temperature drops quite significantly - a little over 1 degree Celsius. Prof. Manger argues that this is something very dangerous for an aquatic mammal living in cold water. According to Prof. Manger, in water, a resting mammalian body loses heat at a rate 90 times faster than in air. The cetacean brain compensates for this heat loss by initiating a strange form of sleep that lacks REM (rapid eye movement), and where only one half of the brain sleeps at a time. This allows the cetacean brain to continue producing heat and keeps the body's muscles moving, preventing excessive heat loss when resting. This type of sleep will also increase production of a neuro-chemical called noradrenaline that will increase the metabolism (and thus, heat production) of the non-neural cells of the brain. Prof. Manger believes that it was the need for thermogenesis alone that triggered the evolution of the cetacean brain into its modern form and told The Dolphin Pod that "there is no need to posit at all a need for complex information processing as an evolutionary pressure leading to larger brain size in cetaceans."

Looking for evidence of a relationship between current oceanic water temperatures and the brains of living cetaceans, Prof. Manger compared high and low water temperatures from the ocean habitats for various cetacean species, as well as temperature range to cetacean body size, brain size, and EQ (encephalization quotient). EQ is measurement of expected brain size relative to body size. Prof. Manger found a significant correlation between EQ and temperature range, which suggested that the scaling of brain-to-body size found in cetaceans must somehow be linked to oceanic temperature; something you may expect to find if cetacean brains are indeed designed for producing heat.

Dr. Lori Marino, however, does not agree with this interpretation of the data. She points out that the link between cooler water temperatures and the emergence of large brains could just as easily have been connected with a change in the way cetaceans hunted their prey. Perhaps cooler water temperatures meant that there were fewer fish available, forcing cetaceans to evolve larger and smarter brains so as to better find food. Furthermore, she states: "although EQ increased dramatically in cetaceans around 30 million years ago, brain size did not increase all that much. The dramatic increase in EQ about 30 million years ago that Manger touts as support for his hypothesis is due to a significant but modest increase in average brain size from 749 g (archaoecetes) to 782 g (Oligocene odontocetes) and a much more dramatic decrease in average body size from 1,654 Kg to 207 kg. Manger's hypothesis relies upon a much larger increase in brain size than what actually occurred. By focusing on EQ, Manger is being misleading."

Dr. Marino's research into the evolution of cetacean brains offers a very different explanation as to the reason cetaceans (particularly dolphins) evolved large brains - an explanation that is commonly accepted in the scientific community. Dr. Marino says "My ideas about why cetaceans became so encephalized and intelligent focus on behavioral ecology, sociality, and communication. Many cetaceans show convergent capacities with some other mammal groups, such as primates and elephants". In other words, dolphins evolved large brains to meet the demands of their environment, and it was their environment that required them to produce more complicated and 'intelligent' behavior - primarily social behavior.

The two hypotheses offered by Dr. Marino and Prof. Manger offer alternative explanations as to why cetacean evolved large brains. I thought perhaps these two explanations could meet somewhere in the middle, and asked Prof. Manger if a brain that evolved for thermoregulation might, as a secondary effect, also be a brain better equipped for processing information, to which he answered: "This may be a possibility, but not in the case of the cetaceans."

Support for this statement can be found in Prof. Manger's second argument, which suggests that the structure of the cetacean brain appears to be designed for thermogenesis and not information processing. He cites more than 20 examples as to why the cetacean brain could not be the brain of an intelligent animal, including:

1. Poorly differentiated neuronal morphology (this means that there are not a lot of different kinds of cells in the dolphin brain. And, the cells that are there are not designed in a way to increase their accessibility to large amounts of information and thus complex processing)

2. Low number of neurons and cortical areas (Neurons are the kind of brain cells that are thought to carry out the bulk of information processing and organize themselves in areas of the cortex that carry out a specific range of functions)

3. Lack of a distinct pre-frontal cortex (the pre-frontal cortex is understood to be the part of the mammalian brain (in humans especially) that carries out the most complex information processing)

4. A large ratio of glial cells to neurons (more on this later)


In my email interviews, Dr. Marino makes some rather strong objections to these claims, which Prof. Manger counters with some equally tough rebuttals. It was, to say the least, a colorful exchange! You can read these remarks in their entirety on The Dolphin Pod website. To whet your appetite, here is a sample of one exchange concerning Prof. Manger's discussion of the pre-frontal cortex. Dr. Marino suggests that "there is no reason to expect that if the dolphin brain has an analogous region to the prefrontal cortex that it would be, in fact, in the front of the brain!" Prof. Manger states in response that "In every single study of the organization of the cerebral cortex of mammals, the prefrontal cortex has been located at the anterior pole of the cerebral hemisphere. All studies, including the thalamic connectivity studies, support the parcellation of the cerebral cortex I have made in the paper."

It should be apparent from these statements that something as seemingly straightforward as a description of the structural organization of the cetacean brain is anything but! And this debate, mind you, is not yet the most controversial in Prof. Manger's paper. Let's continue by expanding a bit on Prof. Manger's point concerning the high ratio of glial cells to neurons found in the dolphin brain.

If neurons are the kinds of brain cells that process information, then glial cells are traditionally considered cells that support the function of neurons by providing nutrition and structure to the brain. Prof. Manger cites in his paper the results of studies done by other scientists that demonstrate that cetaceans brains have a very high ratio of glial cells to neurons. He contends that this fact likely reveals that the cetacean brain is, in his words, 'not optimally wired, presumably impacting negatively on processing efficacy and power of the cetacean cerebral cortex". In other words, cetaceans simply do not have the right type of cell structures to do anything complex with their brains. According to Prof. Manger, it is this overabundance of glial cells that is helping the dolphin brain to generate heat, not process information.

Again, Dr. Marino criticizes this interpretation of glial cell function. She states the following: "One of Manger's most ironic flaws is his outdated view of the role of glial cells in the brain. The older view was that glia were there to provide nutritional and structural support for neurons and that they were basically inert units - "brain glue". However, recent research has shown that, in addition to these previously-known features, glial cells also play an important role in the modulation and coordination of neuronal activity in the brain. They do not just support but actually participate in information-processing and we have only begun to understand the complexity of the role glia may play."

Prof. Manger responds to this however with the following statement "I am well aware of the evidence suggesting the possible role of glia in neuronal activity, and would never deny this. I have forwarded the possibility that this large amount of glia is related to thermogenesis, others, such as Dr. Marino may prefer to think of these as related to intellectual processes, but given the number of coincidences I have gathered and outlined in my paper, it is difficult to support an alternative position."

Prof. Manger argues that it is the combination of all of these brain structure shortcomings that reveal that something is amiss with the cetacean brain. He told The Dolphin Pod: "there are just too many features at several structural levels of the dolphin brain that are not organized in a manner that indicates normal neural processing of information. There is too much comparative neuro-anatomical data that indicates that the brain of the cetacean is not built for complex information processing."

It is obvious by listening to the diametrically opposed points of view expressed by Prof. Manger and Dr. Marino that the relationship between brain structure and intelligence is highly controversial and by no means settled at this point. It is likely that many more decades of research will be required before there is any consensus!

Prof. Manger's final argument, and the one that has landed him in the most hot water with both the general public and other scientists, is the following: The research results claiming that cetaceans (dolphins, in particular) are intelligent are based on unproven assumptions and in actuality cetaceans are not particularly intelligent.

Prof. Manger's evidence from his paper that dolphin behavior studies do not convincingly argue that dolphins are intelligent contain two main arguments:

Argument 1) Dolphins don't have a language

He states in his paper: "The vocalisations of cetaceans have been the subject of speculation ever since Lilly (1962) entertained the possibility of a dolphin language, or 'dolphinese '. Despite extensive efforts to either impose a language upon cetaceans, or decipher their vocalisations, it is clear that no such language exists." I should point out here that this view is very much in step with the modern scientific view of the structure and function of the natural communication system of dolphins.

Argument 2) The claims that dolphins and primates have complex brains capable of similar cognitive and computational abilities are questionable.

Prof. Manger briefly discusses why three abilities cited by Dr. Marino in a 2002 article appearing in the journal Brain Behavior and Evolution -- social group behavior, language comprehension, and self-recognition ability -- do not provide convincing evidence of cognitive complexity in the dolphin brain.

These arguments consist of only a small portion of Prof. Manger's paper, and many scientists have protested that Prof. Manger has not adequately addressed the large body of behavioral evidence that exists stating that dolphins live cognitively complex lives. Dr. Louis Herman of the Kewalo Basin Marine Mammal Laboratory in Honolulu Hawaii, who has spent decades researching the cognitive abilities of dolphins has stated in a posting to the MARMAM email discussion list: "A problem is that Manger's review of the cognitive literature is limited and includes little of the large body of contemporary laboratory and field data showing advanced cognitive skills in dolphins."

In a book chapter titled 'Intelligence and rational behavior in the bottlenose dolphin', appearing in Rational Animals? published by Oxford Press in 2006, Dr. Herman describes his own work with dolphins as follows: "Behavioural studies we carried out during the years subsequent to 1980, as well as many completed earlier, have catalogued a wealth of data on dolphin cognitive traits and abilities that together provide compelling evidence for a level of intelligence commensurate with expectations based on the size, structure, and development of the brain."

I asked Prof. Manger if he believed there is any convincing behavioral evidence from experimental research with cetacean species (particularly dolphins), that might suggest that they indeed have cognitive abilities on par with or exceeding that of primates, citing Dr. Herman's work as an example. Prof. Manger answered very simply: "no."

Dr. Marino has voiced tough criticism of this stance: "Manger blatantly dismisses a whole generation of experimental and observational work on dolphin cognition, behavior, and sociality by hand-waving. This is simply not how science works. The data on dolphin cognitive complexity is there regardless of whether Manger wants it to be there or not. No amount of protesting or hand-waving will make it disappear. Manger neglects most of the large contemporary body of published, peer-reviewed data coming from Herman's lab demonstrating impressive and varied cognitive abilities in dolphins that is fully in keeping with expectations from the large size of the brain and its complex structure."

Concerning Prof. Manger's criticism of her 2002 paper, Dr. Marino states, "there are three indisputable findings that Manger simply cannot make go away without completely dismissing the validity of the entire peer-reviewed scientific process. First, bottlenose dolphins recognize themselves in mirrors. In 2001, Diana Reiss and I provided irrefutable evidence of this in our paper in PNAS (Proceedings of the National Academy of Sciences). Manger claims that we relied upon latency measures to infer cognitive activity. In that paper, we tested several hypothesis based on a number of parameters, including latency. But, the critical outcome measure was behavior at the mirror with respect to the mark. So he is simply incorrect. Second, years of research by Louis Herman and his colleagues have shown that bottlenose dolphins can comprehend syntactic sentences and abstract concepts. Short of reviewing the entire literature here I can only suggest that Manger go back and do that for himself and then articulate in a more cogent way just what it is about this research that he doesn't accept. Third, again, work by people like Richard Connor, Hal Whitehead, and many others have documented complex behaviors such as alloparenting, division of labor, coalition formation, cooperation, and intergenerational transmission of learned behaviors in cetaceans. If Manger wants to suggest that these characteristics are not complex, well, I would like to see what would pass as complex for him. In general, what Manger does is dismiss everything in the literature but provides no alternative criteria for what would be acceptable evidence of cognitive complexity".

The Dolphin Pod asked Prof. Manger what behaviors are evidence of intelligence in animal species, he stated: "The evolution of intelligence and comparing intelligence across species is a very difficult task. However, much depends on your definition of intelligence. Personally, I look at two factors:
How fast is information being processed?
How much information is being processed simultaneously?"

Prof. Manger provides more detail as to how to go about testing intelligence in animals, which you can read in the copy of my interview with him on The Dolphin Pod website. Prof. Manger believes that, given the structural problems with the dolphin brain that were described earlier, dolphins would be unlikely to perform well on the kinds of tasks he outlines. He states: "It is my feeling that due to the structure of the brain cetaceans would have great difficulty in achieving a task set up as described above, a task which both rats and goldfish can achieve."

But, the evidence presented by Prof. Manger that suggests that the structure of the cetacean brain is an important factor in determining a dolphin's level of intelligence on the whole does not sway many other scientists. Dr. Lance Barrett-Lennard of the Vancouver Aquarium Marine Science Centre provided a rather concise summary of this viewpoint in an interview with The Globe and Mail with the following statement: ''A dolphin could have a brain the size of a walnut and it wouldn't affect the observations that they live very complex and social lives.''

Concerning the observations of complex social behaviors, Prof. Manger states in his paper: "Other social behaviours listed by Marino (2002), such as alloparental care, cultural transmission, fission-fusion societies, interpod warfare, and intrapod alliances, all rely on behavioural observations and have not been sufficiently documented to allow independent scrutiny."

This view, however, is not widely accepted. Two decades of research on the behavior of wild bottlenose dolphins in Shark Bay, Australia, have produced a series of studies describing in great detail the social complexity of this population. In a book chapter titled 'Social cognition in the wild: Machiavellian dolphins?' in Rational Animals?, Dr. Richard Connor and Dr. Janet Mann review field studies of this dolphin population. They offer compelling evidence for the evolution of a cognitively complex dolphin brain able to cope with a complicated social environment. Connor and Mann state in this chapter: "our Shark Bay discoveries suggest strongly that, apart from primates, no animal group offers more potential for productive exploration of the relationship between brain size, cognitive skills, and behaviour than cetaceans."

I asked Prof. Manger if he envisions future papers where he may address these criticisms and offer an alternative interpretation of the current behavioral data in more detail. He responded by saying: "I am uncertain as to the extent and usefulness of future papers dealing with the reported behaviour in dolphins and whales, as without the appropriate brain, there is no intelligent behaviour."

This seems to be where the largest gap exists between Prof. Manger's arguments and the current scientific mainstream opinion. Whereas Prof. Manger states: "we cannot divorce structure from function in the way that many who study dolphin behaviour have been doing currently and for the last 50 years", Dr. Herman has written that 'it is behavior, not structure, that measures the intellectual dimensions and range of the species". Those studying dolphin behavior say that the proof of dolphin intelligence is in their behavior, but Prof. Manger believes that the proof of a lack of intelligence can be found in the structure of the dolphin brain. These two viewpoints do not meet in the middle.

I believe I am correct in stating that Prof. Manger's ideas are very much outside of the main-stream of thinking when it comes to our understanding of dolphins as intelligent animals. Prof. Manger's ideas have received rather strong criticism from both scientists and the general public. Concerning this flood of criticism, Prof. Manger told The Dolphin Pod: "It has also been said that I am funded/paid off by the tuna industry and the whaling countries, which is complete nonsense. I am a scientist who has examined the data and forwarded a hypothesis that was extensively peer-reviewed. There is no conspiracy theory here. … several people have suggested that I "hate" dolphins and condone a "mass slaughter" of the remaining marine wildlife. Again, this is nonsense. My science is directed at finding the truth of the matter. I study the brains of various animals in an attempt to understand the animals themselves in a more realistic manner. With a proper understanding, we can devise appropriate management strategies of animals that will, in the long-term, maintain and protect biodiversity against the human factor in the environment."

Prof. Manger's hypothesis and his interpretation of the behavioral data concerning dolphin intelligence are controversial, and have certainly shaken things up in the dolphin world. But, science is science, and if a hypothesis should fail, it should do so based on solid evidence against it, and not simply because it is an unpopular point of view. How the behavioral evidence that dolphins are cognitively complex animals is to be reconciled with Prof. Manger's observations concerning the oddly-structured dolphin brain, and how this all relates to dolphin intelligence is likely something that science will be busy working out for years to come.

Read a complete transcript of the interviews with Prof. Manger and Dr. Marino

 

Interviews with Prof. Paul Manger and Dr. Lori Marino: the dim dolphin controversy

Table of Contents (click on link to navigate)
Round 1 questions Prof. Manger
Round 1 questions Dr. Marino
Round 2 questions Prof. Manger
Round 2 questions Dr. Marino

Questions Round 1 Dr. Manger

The Dolphin Pod: What kind of research/evidence is necessary to lend support to the thermogenetic hypothesis of cetacean brain evolution?

Prof Manger: To support such a hypothesis, data on four fronts must be supported. First, there must be a point in the course of cetacean evolution when temperature would become a significant environmental selection pressure. Second, the fine structure of the extant cetacean brain must show features that are in accord with temperature being an influence. Third, the altered brain-body weight scaling of extant cetaceans must be shown to be influenced by temperature, and fourth, the actual size of the extant cetacean brain must be shown to be the result of water temperature acting as a selective pressure. Currently information relating thermogenesis to cetacean brain evolution is summarized in my paper and involves:

1) Unihemispheric slow wave sleep (USWS)
2) Excess glia and its function
3) The potential interaction of noradrenaline with glia and USWS
4) The startling historical coincidence of increased brain size with drops in water temperature in cetacean evolution
5) The strong relationship between EQ and water temperature range in extant cetaceans
6) The birth weight of young cetaceans

Additional information that is currently published includes the fact that the newborn cetacean swims continuously in early life (Lyamin's studied published in Nature).

Future experimentation could include studies that look at:
1) The effect of changes in water temperature on the physiological nature of sleep in the cetaceans. Would increased water temperature lead to more pronounced USWS? If water temperature were raised enough could clear signs of REM sleep be found? This must be done with physiological recording of the EEG of the two hemispheres of the sleeping cetaceans.
2) How does the locus coeruleus of the cetacean compare to other mammals? Does it have more neurons than would be expected for a mammal of its brain weight? If yes, then perhaps the cetacean brain is producing a great deal more noradrenaline that even currently anticipated.
3) What are the specific thermal mechanisms at a molecular level that are generating heat in the mammalian brain and what form do these take in the dolphin brain?

The Dolphin Pod: In this paper, as in your 2003 paper in J. Sleep Res., you hypothesize that unihemispheric slow-wave sleep and lack of REM sleep in cetaceans functions to compensate for heat loss to the water during sleep, and that a need for thermoregulation was the selective pressure leading to the evolution of USWS. Do any of the data you describe in this paper concerning variations in ocean temperatures for core habitats of and blubber thickness for various species (both cetaceans and other marine mammals) lend support to this hypothesis?

Prof Manger: Yes. The relationship between brain weight and body weight (EQ) and the range of water temperature (TR) are strongly correlated. Blubber thickness is known to correlate with body size in all marine mammals (paper by RYG, M., LYDERSEN, C., KNUTSEN, L. Ø., BJORGE, A., SMITH, T. G. & ØRITSLAND, N. A. (1993). Scaling of insulation in seals andwhales. Journal of Zoology (London) 230, 193-206.), thus I would expect some correlation to exist between ocean temperatures and blubber thickness, but in cetaceans the clear and strong correlation is between EQ and TR.

The Dolphin Pod: Are there, for example, correlations between differences in structure or firing rates of locus coeruleus neurons and ocean temperatures ranges across species?

Prof Manger: This unfortunately has not been studied, and may be very difficult to study. Recording discharge rates of locus neurons in freely moving animals requires extensive invasive surgery to implant the electrodes, and then requires the sacrifice of the animal at the completion of the experiment to verify electrode placement. I seriously doubt whether permission to undertake such a technically difficult study would ever be granted, although the results would be extremely interesting. A very recent study by Ridgway and colleagues (Functional imaging of dolphin brain metabolism and blood flow, J Exp Biol 209:2902-2910) does indicate that what I have hypothesized regarding firing rates of locus neurons does coincide with USWS. Perhaps more imaging data of this sort may provide further support for the ideas I propose.

The Dolphin Pod: Does the thermogenetic hypothesis of cetacean brain evolution assume that the need for more complex information processing was not an evolutionary pressure for a large EQ in cetacean species,

Prof Manger: Yes.

The Dolphin Pod: or simply that it had a secondary or minor influence?

Prof Manger: There is no need to posit at all a need for complex information processing as an evolutionary pressure leading to larger brain size in cetaceans. The microstructure of the cetacean brain indicates that the brain is not a complex information processor.

The Dolphin Pod: Could greater 'information processing' power have been an emergent property of a brain that evolved for thermoregulation?

Prof Manger: This may be a possibility, but not in the case of the cetaceans. There is too much comparative neuroanatomical data that indicates that the brain of the cetacean is not built for complex information processing (see comments re: Elston's work on primates below).

The Dolphin Pod: If thermogenesis is the primary reason for the evolution of large brains for cetaceans, why is the difference both in EQ and CI for mysticetes vis-à-vis odontocetes so large?

Prof Manger: This is not the case. The largest odontocete, Physeter catadon, has an EQ of 0.44 which is just above the EQ found for two species of Balaenopteridae (B. borealis and B. physalus both of which have EQs of 0.43). The difference you are perceiving here is one that is related to size, the baleen whales in general are much larger than the toothed cetaceans, and thus due to negative allometric scaling (the body weight increases more rapidly than brain weight, i.e. for every doubling in body weight of a cetacean the brain only increases by a factor of 1.3) may be interpreted as a difference, but this isn't the case.
In terms of the CI there is only one available data point for the mysticetes. More research on the volumetric divisions of the brains of the mysticetes and odontocetes (such as the work by Stephan, Baron and colleagues on primates, insectivores and bats) is required to determine the accuracy of this single data point (which I obtained from the literature).

The Dolphin Pod: Were these two sub-orders subject to different evolutionary pressures in terms of thermogenesis?

Prof Manger:
No. The microstructure of the mysticete brain appears to be the same as that of the odontocete, indicating similar evolutionary pressures creating a brain that worked (and continues to work) in the environment of the most common recent ancestor of the two sub-orders.

The Dolphin Pod: You discuss how acoustic specialization of the odontocete brain for processing biosonar is likely not a driving force behind the evolution of large brain size for this suborder. Is there a fundamental difference in the neuroarchitecture of odontocete and mysticete brains due to the presence of areas dedicated to biosonar processing that may explain the difference in CI and EQ between these two suborders?

Prof Manger: It really isn't known if there is a difference in the way the brains of the two groups process acoustic information, the experiments just haven't been done. I would imagine there would be some differences due to the echolocation in odontocetes, and these might be most easily identified in a structure like the inferior colliculus (which creates an auditory space map). Unfortunately, well-preserved brains of mysticetes are not readily available for scientific observation. Much more information regarding the structure of the mysticete brain is needed to answer your question fully.

The Dolphin Pod: Some authors have described a large area of 'nonprojectional cortex' in the odontocete brain. According to your findings, is this an accurate description for any of the areas of the dolphin brain that you describe, and how does this area of the cortex relate to either a discussion of thermogenesis or information processing?

Prof Manger:
I am not aware of any region of the cetacean cortex that may be termed "non-projectional cortex". For example, the paper by Revishchin and Garey (1990) The thalamic projection to the sensory neocortex of the porpoise, Phocoena phocoena. J Anat 169:85-102. indicates that all regions of cortex receive direct thalamic projections. I am not aware of any region of the cetacean cortex that might be described as non-projectional. This is perhaps an old-fashioned term for regions of the neocortex that are not considered primary sensory areas (these being primary motor, somatosensory, visual and auditory areas). We now know that these "associational" "secondary" or "tertiary" regions of cortex receive direct thalamic projections in all mammalian species. So there is no "unexplainable" region of cortex in cetaceans.

The Dolphin Pod: In your opinion, is there any convincing behavioral evidence from experimental research with cetacean species (particularly odontocetes), that might suggest that they indeed have cognitive abilities on par with or exceeding that of primates? As examples:

a.. Herman's work with symbol manipulation
b.. Xitco's work with pointing, reference and joint attention

Prof Manger: No.

The Dolphin Pod: A follow-up question: if, for example, the results of these experiments are due to a 'basic form of learning', why have the results of these and similar experiments not been replicated more often in species other than dolphins and primates?

Prof Manger: One reason is due to a lack of trying. If you examine the literature on the cognitive abilities of birds you might be astounded at what a bird can achieve. Such features as cognitive dissonance in parrots, following of human eye gaze in corvids, tool use and manufacture, and even deliberate deception have been well documented (reviewed in Butler A, Manger P, Lindahl B, Arhem P. Evolution of the neural basis of consciousness: a bird-mammal comparison. Bioessays 27: 923-936 (2005)).

Also, I might ask at this point, why have many of the behavioural tests done in other animals not been achieved with dolphins? For example, I am not aware of a radial arm maze test (that investigates spatial memory) ever having been performed on dolphins? I feel your question here should be reversed, and we should be asking why have many of the standard behavioural paradigms used in many other species not been used on dolphins?


The Dolphin Pod: In your opinion, what are the strongest neurological correlates of intelligence for brains in general?

Prof Manger: The brain is a hierarchically organized processor of information. This spans from the molecular level, through receptor complexes, synapses, parts of neurons (such as dendrites), single neurons, clusters of neurons, nuclei and cortical areas, systems, with behaviour being the expression of this processing. Dolphin brains are mammalian brains, and as such, follow the patterns established early in mammalian evolution. For a brain to be a complex processor of neuronal information all levels of this organizational hierarchy must be functional, otherwise the brain fails. For example, in recent work with colleagues (Elston GN, Benavides-Piccione R, Elston A, Zietsch, B., Defelipe J, Manger P, Casagrande V, Kaas JH. Specializations of the granular prefrontal cortex of primates: implications for cognitive processing. Anat Rec A Discov Mol Cell Evol Biol. 2006 Jan;288(1):26-35.) we have shown that with increases in brain size in primates, the complexity of the neuron increases dramatically. This increase in complexity, and thus functionality, will have a flow on effect to higher levels of brain organization, and thus result ultimately in more complex behaviour. There are too many examples within the brains of cetaceans that violate the evolutionary patterns found in other mammals. These are listed in the paper, but include:

Low cell density
Lack of layer 4
Thin thickness for brain size
Low number of cortical areas
No/inordinately small pre-frontal cortex
High glia:neuron ratio
Low corticalization index
Small and poorly differentiated hippocampus
Unbalanced proportion of elements of the neuropil
A majority of poorly differentiated and aspinous neurons

There are just too many features at several structural levels of the dolphin brain that are not organized in a manner that indicates normal neural processing of information, thus the hierarchy typical to mammals fails. Any level of this hierarchy can become more or less complex during evolution. Increases in complexity will lead to increased behavioural sophistication and vice versa. All levels of neural organization must be investigated. Size can be important, as allometric increases in overall brain size may cause spandrels in complexity at lower levels of organization and thus increased complexity in neural processing, and this may indeed be found in primates and other species, but there is no evidence for this in cetacean species. A somewhat convoluted answer, but in brief, the whole shebang must be working, a weak link causes failure.

The Dolphin Pod: You state that the evidence in favor of significant intellectual capacities of dolphins is tenuous. In your opinion, what behaviors are evidence of intelligence in animal species, and which animals display these behaviors? How do dolphins measure up when compared to the overall intelligence of other animal species?

Prof Manger: The evolution of intelligence and comparing intelligence across species is a very difficult task. However, much depends on your definition of intelligence. Personally, I look at two factors:

1) How fast is information being processed?
2) How much information is being processed simultaneously?

The crucial demands for any behavioral model used to test intelligence are: (1) The instrumental response of the animal has to be a complex behavior, i.e. consisting of a sequence of locomotor actions rather than just a simple behavioral response to a stimulus. This should reflect the animal's understanding of the cognitive task (the application of knowledge). The experimental environment should thus allow more than one equivalent behavioral response. (2) The task semantics (rules of behavior) must contain a complex logic (if - then); only in this case can an animal learning the task be compared with human-like intellectual activity. In order to solve this kind of logic problem the animal should demonstrate substantial cognitive abilities (i.e. be capable to forecast the result of its actions). (3) The rule governing behavior should be set up in a general form so that learning a task would require the generation of several working hypotheses. Moreover, an animal can interpret the task rule in its own manner depending on its cognitive abilities and experience. (4) Learning should not be completed after one trial. To meet this criterion the amount of information in the experimental environment should exceed the amount of information that an animal is capable of processing simultaneously.
In aiming to study behavioral self-organization in animals (spontaneous vs. trained), the learning procedure should be such that it allows the animal to control the experimental situation - a free-choice learning procedure satisfies this condition. The main feature of the free-choice method is that it presents to the animal all of the information about the task from the beginning of the learning period. Another characteristic feature of this method is that the experimenter does not interfere in the animal's behavior in any way. The different prompted signals used by an experimenter during training or during an autoshaping procedure that guide an animal to a task goal, help to form the desired habit and make solving the problem easier. In the free-choice learning paradigm, the session time is the only condition limited by the experimenter.

Dolphins have not been tested in this manner in any of the reported behavioural studies, therefore, they cannot be "ranked". It is my feeling that due to the structure of the brain the cetaceans would have great difficulty in achieving a task set up as described above, a task which both rats and goldfish can achieve (papers documenting this have beeb published by Kira Nikolskaya - but in Russian).

The Dolphin Pod: Many scientists researching dolphin cognition might argue that examination of neuroarchitecture at this stage in our knowledge of how brain structure relates to behavior, is unlikely to reveal anything useful about the cognitive abilities of an animal. The bulk of claims that dolphins are intelligent animals in recent decades have come from behavioral studies. For example, Schusterman's work with both dolphins (with a high EQ) and sea lions (with a low EQ) has revealed that both species are capable of learning cognitively complex tasks - tasks that other (presumably 'less intelligent') animal species have difficulty learning. Do these kinds of results reveal that complex cognition functions independently of structural measurements like EQ and neuroarchitecture? How would you respond to criticisms of your own claims in this paper that state that intelligence is a measure of intelligent behavior, and not brain structure, thus an argument for the intelligence of an animal based on neuronal-structure is 'old fashioned'?

Prof Manger: These would be rather facile claims, as they indicate that if anything "looks" like intelligent behaviour to the observer, then it must be intelligent - even if no nervous system at all exists! For example, a hypothetical bacteria to which water is lethal may avoid water through a simple sensory mechanism. This may be considered intelligent behaviour, as the bacteria avoided a lethal situation. Do we really consider this intelligent behaviour?

The Dolphin Pod: Is there anything else that you would like to add, clarify or comment on regarding your hypothesis, dolphin intelligence or criticisms of your ideas that have appeared in the media?

Prof Manger: There has been a great deal of criticism of the ideas I have forwarded, however, I am yet to find any criticisms from people who have fully understood the hypothesis in it's entirety - most have taken small sound bites and missed the point. I would encourage people to thoroughly read what I have written and when understood then find fault. A healthy, open, and honest scientific debate is appropriate. Statements calling to have me "muzzled", "dismissed", "ostracized", and so on will do no good to the central point of research, which is the revelation of the truth - even if it is uncomfortable and threatens heartfelt beliefs.

It has also been said that I am funded/paid off by the tuna industry and the whaling countries, which is complete nonsense. I am a scientist who has examined the data and forwarded a hypothesis that was extensively peer-reviewed. There is no conspiracy theory here.

Lastly, several people have intimated that I "hate" dolphins and condone a "mass slaughter" of the remaining marine wildlife. Again this is nonsense. My science is directed at finding the truth of the matter. I study the brains of various animals in an attempt to understand the animals themselves in a more realistic manner. With a proper understanding we can devise appropriate management strategies of animals that will in the long-term maintain and protect biodiversity against the human factor in the environment.

 

Questions Round 1 Dr. Marino


The Dolphin Pod: Do you believe that ocean temperatures could have been the primary or even sole evolutionary pressure responsible for the large brain size (i.e. EQ) of odontocetes?

Dr. Marino: We currently do not have enough resolution on the paleoclimatic data for the Eocene-Oligocene transition to determine whether changes in oceanic temperatures played a role in selecting for larger brains in cetaceans back then. However, even if we were to obtain that level of resolution the most we would be able to say is that there is a temporal correlation between oceanic cooling and increases in encephalization in cetaceans. Obviously some factors did play a role in shaping the evolution of the cetacean brain but selection does not always work in a direct manner. It is highly plausible that oceanic cooling could have produced a change in prey availability that would have provided an impetus for changes in behavioral ecology in cetaceans that led to increased encephalization. Any number of scenarios are plausible at this point.

But it is critical to point out that when we test for correlations between EQ and current maximum and minimum temperature for oceans in which modern cetaceans live we find that only body size is important. The colder the water the bigger the body. But brain size has nothing to do with it once you control for body size.

The Dolphin Pod: Could the cetacean cortex (containing an unusually high number of glia cells) have evolved for thermogenesis and not information processing? Are there other hypotheses as to why cetaceans have an unusually high glia:neuron index?

Dr. Marino: One of Manger's most ironic flaws is his outdated view of the role of glial cells in the brain. The older view was that glia were there to provide nutritional and structural support for neurons and that they were basically inert units - "brain glue". However, recent research has shown that, in addition to these previously-known features, glial cells also play an important role in the modulation and coordination of neuronal activity in the brain. They do not just support but actually participate in information-processing and we have only begun to understand the complexity of the role glia may play.

The Dolphin Pod: Is Dr. Manger correct in stating that there are "no neurological correlates for the purported intellectual abilities of cetaceans"?

Dr. Marino: No, he is not correct in any meaningful way. We know, for instance, that the life history periods typical of highly cognitive lifestyles are correlated with residual brain size in cetaceans, just as they are in primates and birds. Long lives, long juvenile periods and long periods of adult reproductive time are thought to be favored by what we call "cognitive buffering", the ability to cope with life threatening situations (famine, predation, fluctuations in climate) with flexible behavior.

The Dolphin Pod: Is Dr. Manger correct that the following features of the cetacean brain have negative impacts on cortical processing:

1.. poorly differentiated neuronal morphology
2.. low number of neurons and cortical areas
3.. lack of a distinct pre-frontal cortex
4.. small hippocampal formation


The main substantive point that Manger misses is this. Cetacean brains have been on an independent evolutionary trajectory for close to 55 million years. During all that time the dolphin brain evolved a unique combination of features. The result of this process is that one cannot readily make one-to-one comparisons between cetacean brains and the brains of other mammals without taking this different evolutionary history into account. Manger accepts that cetacean brains are highly different from other mammal brains but his arguments belie the fact that he understands what this means. Here are my specific comments:

Poorly differentiated neuronal morphology - the view of the dolphin cortex as a primitive homogeneous simplified mass of tissue is a very outdated interpretation of dolphin neurobiology. Manger's acceptance of this outdated view is revealed by the fact that he states on page 11 of his paper that the dolphin cortex can best be described by terminology originating from 1909 and claims that essentially no new conclusions about the dolphin cortex have been reached since 1879. This is simply not true. In fact, one of his most stunning omissions is a widely-read 2005 paper on cetacean cortical complexity by Patrick Hof, Rebecca Chanis, and myself in which we describe the cortical cytoarchitecture of the bottlenose dolphin brain and show that the dolphin cortex is highly differentiated and contains a wide variety of different neuronal morphotypes.

Low number of neurons and cortical areas - This is a puzzling claim to make because no one knows how many neurons are in cetacean brains and we do not have adequate data on the number of cortical areas either.

Lack of a distinct pre-frontal cortex - This argument relies upon a very concrete way of looking at brain anatomy. Manger is absolutely correct in that there is little tissue anterior to the motor and somatosensory regions of the dolphin neocortex. He is also correct in that what little tissue there is does not resemble primate prefrontal cortex. However, he does not seem to understand that when we speak of identifying "prefrontal cortex" in any meaningful functional way what is meant is that we are seeking the functional and architectural analog to the primate prefrontal cortex in the dolphin brain. There is no reason to expect that if the dolphin brain has an analogous region to the prefrontal cortex that it would be, in fact, in the front of the brain!

Small hippocampal formation - The hippocampal formation in cetacean brains is reduced. But only certain components of it are small. Other components, such as the amygdala, are well developed. Moreover, Manger is not correct when he states that the cetacean limbic lobe is under-developed. In fact, the limbic lobe and the insular cortex are extremely elaborated in cetacean brains and many authors have remarked on this feature of cetacean brains in the literature. Finally, Manger neglects to mention that cetacean brains contain a paralimbic lobe that is not found in other mammal brains. We do not know the function of the paralimbic lobe in dolphins but it is fair to mention it in a comparative context.

The Dolphin Pod: Dr. Manger singles out your 2002 paper from Brain, Behavior and Evolution, discussing how three cited examples of complex cognitive behaviors in cetaceans (social group behavior, language comprehension, and mirror self recognition) are actually poor indicators of cognitive complexity in cetaceans as these are based on 'unreliable assumptions'. Are his criticisms accurate?

Dr. Marino: I'm not sure what kind of 'unreliable assumptions' Manger thinks these studies are based on. But there are three indisputable findings that Manger simply cannot make go away without completely dismissing the validity of the entire peer-reviewed scientific process. First, bottlenose dolphins recognize themselves in mirrors. In 2001 Diana Reiss and I provided irrefutable evidence of this in our paper in PNAS. Manger claims that we relied upon latency measures to infer cognitive activity. In that paper we tested several hypothesis based on a number of parameters, including latency. But the critical outcome measure was behavior at the mirror with respect to the mark. So he is simply incorrect. Second, years of research by Louis Herman and his colleagues have shown that bottlenose dolphins can comprehend syntactic sentences and abstract concepts. Short of reviewing the entire literature here I can only suggest that Manger go back and do that for himself and then articulate in a more cogent way just what it is about this research that he doesn't accept. Third, again, work by people like Richard Connor, Hal Whitehead, and many others have documented complex behaviors such as alloparenting, division of labor, coalition formation, cooperation, and intergenerational transmission of learned behaviors in cetaceans. If Manger wants to suggest that these characteristics are not complex, well, I would like to see what would pass as complex for him. In general, what Manger does is dismiss everything in the literature but provides no alternative criteria for what would be acceptable evidence of cognitive complexity.

The Dolphin Pod: Do you believe that Dr. Manger's discussion of vocalizations and language comprehension in cetaceans convincingly argues that cetaceans (particularly odontocetes) do not have an atypical capacity for artificial language usage and comprehension for a non-human animal species?

Dr. Marino: As he does with the corpus of literature showing dolphins are cognitively and socially complex, Manger refuses to acknowledge the prodigious body of work by Louis Herman and his colleagues showing that bottlenose dolphins can mentally represent and understand abstract concepts and comprehend an artificial syntactically-based communication system containing thousands of unique sentences composed of symbolic gestural and auditory "words". The only other species to show this rare capacity are bonobos and humans.
Manger fails to understand that the key feature of a language that gives it power is not the word but the sentence. Herman's work has shown that bottlenose dolphins are able to process instructions given to them in sequences of symbols (sentences) as long as five words in length, and in which word order, a syntactic device, as well as word meaning or reference, determines the meaning of the sentence as a whole. Manger neglects most of the large contemporary body of published, peer-reviewed data coming from Herman's lab demonstrating impressive and varied cognitive abilities in dolphins that is fully in keeping with expectations from the large size of the brain and its complex structure.

The Dolphin Pod: Do you think that the current behavioral evidence suggesting that dolphins are capable of cognitively complex behaviors is, as Dr. Manger states, 'tenuous, and based upon untested, unproven, unquestioned, and anthropomorphic assumptions"?

Dr. Marino: Absolutely false. This is Manger's most egregious claim and one that deserves very little attention. Manger blatantly dismisses a whole generation of experimental and observational work on dolphin cognition, behavior, and sociality by hand-waiving. This is simply not how science works. The expression "The proof is in eating the pudding" is apropos' here. The data on dolphin cognitive complexity is there regardless of whether Manger wants it to be there or not. No amount of protesting or hand-waiving will make it disappear.


The Dolphin Pod: Dr. Manger offers a new method for calculating corticalisation index (CI) by separating out gray and white matter. This new method places the CI of odontocetes well below the average of most other mammals. In your opinion, is this new method for calculating CI superior to the method first used by Glezer et al. (1988)? Does this reveal anything significant concerning the organization of the dolphin cortex?

Dr. Marino: This index per se reveals nothing about cortical complexity because the large quantity of white matter in the cetacean brain is exactly what one would predict on the basis of scaling of a brain of large absolute size. In other words, when brains get large the amount of white matter increases simply to maintain processing speed and efficiency. Furthermore, recent comparative MRI studies show that the human brain has a higher relative amount of white matter in the prefrontal cortex than other primates. More connections are presumed to contribute to faster information processing, contrary to what Manger concludes for cetaceans. In fact. Manger's own data, presented in his Table 2, shows that when computing the volume of grey matter as a percentage of total brain volume, humans fall below the other primate species he lists.

The Dolphin Pod: According to your research, has Dr. Manger correctly described the neuroarchitecture of the cetacean brain, and is he correct in stating that cetacean brains "do not indicate a structure supportive of high levels of intellectual capacities"?

Dr. Marino: As I mentioned previously Manger's view of dolphin neuroarchitecture is grossly outdated and he fails to appreciate the fundamental consequences of evolutionary divergence on brains.

The Dolphin Pod: Do you believe that Dr. Manger's hypothesis that "unihemispheric slow-wave sleep and lack of REM sleep in cetaceans functions to compensate for heat loss to the water during sleep" could explain the evolution of unihemispheric slow-wave sleep in cetaceans?

Dr. Marino: I don't immediately accept his argument for one simple reason - there is no evidence for it. Manger relies upon comparisons of cetaceans with other aquatic mammals to bolster his argument. But it is this very comparison that weakens his hypothesis. Despite his claim to the contrary, the brains of cetaceans, pinnipeds, and sirenia are all extremely different on a number of dimensions and there are no commonalities across them that point to selection for thermoregulation in an aquatic environment.

The Dolphin Pod: Following from your own research, what do you believe to be the major evolutionary pressures that facilitated the evolution of large brain sizes in cetaceans?

Dr. Marino: My hypotheses about evolutionary pressure for large brain size in cetaceans are data-based. Dolphins and other cetaceans are extremely cognitively and socially complex. They also possess sophisticated echolocatory, cross-modal perceptual, and vocal learning abilities. My ideas about why cetaceans became so encephalized and intelligence focus on behavioral ecology, sociality, and communication. Many cetaceans show convergent capacities with some other mammal groups, such as primates and elephants. My colleagues and I are focusing on identifying the common selection pressures across these groups that might have led to convergent cognition.

The Dolphin Pod: Do you have any further remarks on this paper (its claims and methods), or comments relating to the criticisms of your own work that were brought up in this paper?

Dr. Marino: No further comments.

Questions Round 2 Prof. Manger


The Dolphin Pod: Do you agree with Dr. Marino's comments:
(Qouted from Dr. Marino): "We currently do not have enough resolution on the paleoclimatic data for the Eocene-Oligocene transition to determine whether changes in oceanic temperatures played a role in selecting for larger brains in cetaceans back then. However, even if we were to obtain that level of resolution the most we would be able to say is that there is a temporal correlation between oceanic cooling and increases in encephalization in cetaceans. Obviously some factors did play a role in shaping the evolution of the cetacean brain but selection does not always work in a direct manner. It is highly plausible that oceanic cooling could have produced a change in prey availability that would have provided an impetus for changes in behavioral ecology in cetaceans that led to increased encephalization. Any number of scenarios are plausible at this point."

Prof Manger: Of course several scenarios can be put forward, and indeed what Dr. Marino proposes may be correct. But given the data I have put forward, isn't the simplest explanation the most preferred one - Ockham's Razor? Why convolute the issue with speculations regarding information that we don't have? I have based my conclusions on the available evidence - that published by experts in the field. There does appear to be a good temporal correlation between water temperature and encephalization in cetaceans as outlined in my paper, and given that they are mammals living in water and the high rate of heat loss to the water, surely it is logical to conclude that this will be a significant environmental pressure? In terms of changes in diet, later evolution in the baleen whales saw the genesis of the baleen oral apparatus, however, these were not present in the earlier members of this suborder, thus dietary changes have occurred, and these are correlated to anatomical changes, but this does not appear to correlate with the period when temperature would have been a significant environmental pressure nor when there were significant alterations in the anatomy, size and scaling of the brain.

(Qouted from Dr. Marino): "But it is critical to point out that when we test for correlations between EQ and current maximum and minimum temperature for oceans in which modern cetaceans live we find that only body size is important. The colder the water the bigger the body. But brain size has nothing to do with it once you control for body size."

I am not privy to these calculations, so it is difficult to speculate upon them - how does one control for body size when body size is one of the variables examined? Not only this, EQ is already a control for body size. I can only point out that I did indeed publish the statistically significant correlations between water temperature and body size in my paper, and showed the same with brain size, but none of these correlations indicated a high predictive value (see figure 15), however, the correlation between EQ and water temperature range showed the strongest correlation and highest predictive value. This last correlation is therefore the one I focused upon.

The Dolphin Pod: One of your strongest claims is that the glia:neuron ratio is quite high in cetacean brains, and that this is evidence that this kind of brain could not be a good information processor. Is it correct to say that glia cells play a very limited if any role in information processing in the brain? See Marino's comments below:
(Qouted from Dr. Marino): "One of Manger's most ironic flaws is his outdated view of the role of glial cells in the brain. The older view was that glia were there to provide nutritional and structural support for neurons and that they were basically inert units - "brain glue". However, recent research has shown that, in addition to these previously-known features, glial cells also play an important role in the modulation and coordination of neuronal activity in the brain. They do not just support but actually participate in information-processing and we have only begun to understand the complexity of the role glia may play."

Prof Manger: I am well aware of the evidence suggesting the possible role of glia in neuronal activity, and would never deny this. This is why I state in the paper that (pg 314): "It has been suggested that one role of glia in the vertebrate brain is thermogenesis (Donhoffer, 1980; Szelenyi, 1998)." and go on to discuss the evidence supporting thermogenesis as a functional attribute of glia. In fact in different vertebrates, only the mammals and the birds have highly expressed numbers of glia, which is associated with being warm-blooded. Ascribing the above expressed "outdated" and ironically flawed (sic) view of glia to my way of thinking is not correct. In the cetaceans we see an extraordinary abundance of glia, which requires an explanation. I have forwarded the possibility that this large amount of glia is related to thermogenesis, others, such as Dr. Marino may prefer to think of these as related to intellectual processes, but given the number of coincidences I have gathered and outlined in my paper, it is difficult to support an alternative position.

The Dolphin Pod: A follow up question: it has been suggested that Einstein was 'more intelligent' than other humans because his brain had a larger number of glia cells than the average human brain.

Prof. Manger: This is not the case. The reference and abstract of this paper is given below (taken directly from that provided on PubMed):

"Diamond MC, Scheibel AB, Murphy GM Jr, Harvey T. (1985) On the brain of a scientist: Albert Einstein. Exp Neurol.88:198-204. Neuron:glial ratios were determined in specific regions of Albert Einstein's cerebral cortex to compare with samples from 11 human male cortices. Cell counts were made on either 6- or 20-micron sections from areas 9 and 39 from each hemisphere. All sections were stained with the Kluver-Barrera stain to differentiate neurons from glia, both astrocytes and oligodendrocytes. Cell counts were made under oil immersion from the crown of the gyrus to the white matter by following a red line drawn on the coverslip. The average number of neurons and glial cells was determined per microscopic field. The results of the analysis suggest that in left area 39, the neuronal: glial ratio for the Einstein brain is significantly smaller than the mean for the control population (t = 2.62, df 9, p less than 0.05, two-tailed). Einstein's brain did not differ significantly in the neuronal:glial ratio from the controls in any of the other three areas studied."

The Dolphin Pod
: Some studies have shown that glia cell growth in the rat brain increases when rats are exposed to an enriched environment. Does this not suggest that a larger number of glia in any brain might correspond to more information processing and not less?

Prof. Manger: These studies also show significant differences in neuronal morphology (increased dendritic branching, greater spine density etc. which will more directly lead to greater information processing) with enriched environments, thus it is impossible with present knowledge to really support the specific conclusion you indicate above.

The Dolphin Pod: Concerning your 4 features of the cetacean brain that have a negative impact on cortical processing, Dr. Marino made the following comments - do you have a response to these criticisms?
(Qouted from Dr. Marino): "Poorly differentiated neuronal morphology - the view of the dolphin cortex as a primitive homogeneous simplified mass of tissue is a very outdated interpretation of dolphin neurobiology. Manger's acceptance of this outdated view is revealed by the fact that he states on page 11 of his paper that the dolphin cortex can best be described by terminology originating from 1909 and claims that essentially no new conclusions about the dolphin cortex have been reached since 1879. This is simply not true. In fact, one of his most stunning omissions is a widely-read 2005 paper on cetacean cortical complexity by Patrick Hof, Rebecca Chanis, and myself in which we describe the cortical cytoarchitecture of the bottlenose dolphin brain and show that the dolphin cortex is highly differentiated and contains a wide variety of different neuronal morphotypes."

Prof Manger: This paper wasn't cited in mine as my paper was "in press" when this paper was published, therefore it wasn't a "stunning omission" but something that occurred due to timing of the publication process. For the most part, this paper really doesn't add anything new to the literature from what was described in earlier studies. There is no part of the paper that demonstrates neuronal morphotypes previously undescribed (defined by actually anatomy of the neurons themselves and not done with basic stains such as cresyl violet which labels Nissl bodies to reveal the location of the cell body but not the dendritic branching, axonal morphology or chemical nature of the neuron), and on the whole reflects everything that has previously been described - e.g. the location of the giganto-pyramidal cells (which was described in 1951!). There are several claims for additional cortical areas, however, these are not documented in a manner that allows independent scrutiny - for example, no photomicrographs of transitions between cortical areas are given. Moreover, no architectonic map, as provided by Kesarev et al (1977) is provided. On the whole, this study does little except assert statements that are not supported by documentation, and the documented photomicrographs are not different from those previously published.

What appears to be missing in Dr. Marino's above statement is an understanding of the hierarchical nature of neuronal processing of the brain. The hierarchy moves from molecules to molecule complexes to synapses, part of neurons, individual neurons, neuronal clusters, cortical areas/nuclei, and systems resulting finally in behaviour. Changes in morphology can occur at any level of this hierarchy, if for example the neurons were to become more complex, the end result of processing, or behavioural expression, would be more complex without the need for changes, say at the organizational level of cortical areas. If one part of the hierarchy is rather simple in organization, such as the neurons in the dolphin brain (simple in terms of the dendritic arborization and synaptic connectivity), then the hierarchy will be processing less complex information.

The 1909 terminology used in my paper comes from Brodmann's seminal publication on cortical architectonics, and his architectonic map is still widely used today in neurology and the neurosciences. Brodmann is perhaps the most widely respected figure in the field of cortical architectonics, and his work is exemplary. His terminology is used by most neuroscientists, so to indicate that the terminology I have used is outdated is ludicrous.

(Qouted from Dr. Marino): "Low number of neurons and cortical areas - This is a puzzling claim to make because no one knows how many neurons are in cetacean brains and we do not have adequate data on the number of cortical areas either."

Prof Manger: In the paper, on page 310, I have listed the available data indicating the exact published numbers of cortical neuronal density in 3 species of cetaceans and 12 other mammalian species. Cetacean neuronal density is far below that seen in other mammalian species, this is not a puzzling claim, it is published data. Also, see the recently published paper by Poth et al (2005) Brain Res. Bull. 66:357-360.

Regarding the number of cortical areas, I used the only published complete architectonic map of cetacean cerebral cortex, that of Kesarev and colleagues, as a baseline. This study clearly indicates a low number of cortical areas in comparison to many other mammalian species. The results of this study are backed up by the available physiology, also described in the paper. Moreover, a recent study using computer assisted architectonic methods [Fung et al., (2005) Brain Res Bull. 66:353-356] provide evidence for two auditory cortical areas they call PAC (primary auditory cortex) and SAC (secondary auditory cortex) in Pontoporia that are almost identical in location and extent to the regions demarcated Pi and Pli by Kesarev et al (1977) in Tursiops. Thus there is absolutely no reason to question the conclusions I have derived regarding the number of cortical areas in the dolphin - more than one previous study supports my parcellation of cetacean cerebral cortex, the only one claiming to go against it is that of Marino and colleagues.

(Qouted from Dr. Marino): "Lack of a distinct pre-frontal cortex - This argument relies upon a very concrete way of looking at brain anatomy. Manger is absolutely correct in that there is little tissue anterior to the motor and somatosensory regions of the dolphin neocortex. He is also correct in that what little tissue there is does not resemble primate prefrontal cortex. However, he does not seem to understand that when we speak of identifying "prefrontal cortex" in any meaningful functional way what is meant is that we are seeking the functional and architectural analog to the primate prefrontal cortex in the dolphin brain. There is no reason to expect that if the dolphin brain has an analogous region to the prefrontal cortex that it would be, in fact, in the front of the brain!"

Prof Manger: In every single study of the organization of the cerebral cortex of mammals, the prefrontal cortex has been located at the anterior pole of the cerebral hemisphere. This includes studies in monotremes, marsupials, insectivores, chiropterans, primates, ungulates, carnivores, etc. etc.! The observed physiology of the cetacean cerebral cortex indicates that it is organized in the mammalian pattern, with visual cortex posteriorly, auditory laterally, and somato-motor anteriorly. Is Dr. Marino seriously suggesting that the dolphins are an exception to the observed rule of areal organization of mammalian cerebral cortex? To support this claim Dr Marino must known something no-one else does, or has done as yet unreported experiments. As reviewed in my paper, there is no region of the cetacean cerebral cortex that can be readily described as pre-frontal. All studies, including the thalamic connectivity studies, support the parcellation of cerebral cortex I have made in the paper. Dr. Marino appears to be "inventing" a new part of cerebral cortex, one that doesn't exist - see comments below on the "paralimbic lobe" of cetaceans.

(Qouted from Dr. Marino): "Small hippocampal formation - The hippocampal formation in cetacean brains is reduced. But only certain components of it are small. Other components, such as the amygdala, are well developed."

Prof Manger: The hippocampal formation consists of the hippocampus proper, the dentate gyrus, the entorhinal cortex and the subiculum. The amygdala is not part of the hippocampal formation. The hippocampal formation is the portion of the brain responsible for the formation and recall of long-term or enduring memories, and in conjunction with the pre-frontal cortex enables short-term or working memory (both having been demonstrated conclusively in goldfish and are absolutely essential for production of language in humans). The fact that components of it are reduced and poorly organized indicates a compromise in the functioning of this system that is very important for memory and hence all the cognitive processes that require memory.

In my paper I clearly indicate that the amygdala, apart from a loss of the nuclei involved in olfaction, is normally organized (pg. 312). The amygdala is that part of the brain that processes species relevant environmental stimuli and generates the overall state of the brain that we call emotion. It has nothing to do with memory, but rather serves as an interface between the environment and species relevant emotional behaviour.

(Qouted from Dr. Marino): "Moreover, Manger is not correct when he states that the cetacean limbic lobe is under-developed."

Prof Manger: Here Dr. Marino is now questioning the studies and conclusions of several recognized experts of dolphin neuroanatomy. The studies are referenced on page 312 of my paper. She is incorrect in her assertion here. For example, Kruger (1966) indicates that the relative volume of the thalamic portion of the limbic system is almost half that seen in other mammals.

(Qouted from Dr. Marino): "In fact, the limbic lobe and the insular cortex are extremely elaborated in cetacean brains and many authors have remarked on this feature of cetacean brains in the literature."

Prof Manger: The insular cortex is not part of the limbic system. It is that part of the cortex that overlies the claustrum, and is found in all mammals. I have not read anywhere of this regions of the cetacean brain being "extremely elaborated" except in descriptions of the number of gyri and sulci, which applies to the cetacean brain as a whole.

(Qouted from Dr. Marino): "Finally, Manger neglects to mention that cetacean brains contain a paralimbic lobe that is not found in other mammal brains. We do not know the function of the paralimbic lobe in dolphins but it is fair to mention it in a comparative context."

Prof Manger: This is a very unusual assertion. I assume it relates to Dr. Marino's attempt to find an analogue to pre-frontal cortex in cetaceans. The term "paralimbic lobe" has two definitions in the scientific literature, one used for mammals in general, and the other for cetaceans. For mammals, the term paralimbic lobe is referred to as those structures that directly project upon the limbic system, such as the posterior orbital gyrus, insula (or claustro-cortex), nucleus accumbens, caudate nucleus, habenula, interpedunclar nucleus, various hypothalamic nuclei, temporal cortex, and claustrum. These are structures found in all mammals, thus in this sense, the above statement of Dr. Marino is incorrect.

What Dr. Marino appears to be referring to though, is the "paralimbic lobe" of the cetacean cerebral cortex described by Morgane et al., (1980) Brain Res Bull 5 (suppl. 3). In this extensive description of the surface anatomy of the cetacean cerebral cortex Morgane and colleagues describe a region of cortex lateral to the cingulate gyrus (part of the limbic system) that they term, using an anatomical nomenclature (nothing to do with function), the paralimbic (or "around the limbic") lobe. Consequent studies (physiological and connectional) have shown this "paralimbic lobe" to be the primary and secondary visual cortex, as described in my paper (the regions designated Os, Om, and Olm by Kesarev). In later studies of this region of the brain, Morgane and colleagues (1988, J Comp. Neurol. 273:3-25) do not use the term paralimbic lobe, but rather refer to it as visual cortex. Thus, we do know the function of the apparently mysterious paralimbic lobe - it is visual cortex.

Yes, I did not refer to the "paralimbic lobe" in my paper, but used the correct assignation of visual cortex - nothing mysterious in this as all mammals have a visual cortex.

The Dolphin Pod: Concerning your new method of calculating CI and its implications, Dr. Marino made the following comments - do you have a response?
(Qouted from Dr. Marino): "This index per se reveals nothing about cortical complexity because the large quantity of white matter in the cetacean brain is exactly what one would predict on the basis of scaling of a brain of large absolute size. In other words, when brains get large the amount of white matter increases simply to maintain processing speed and efficiency. Furthermore, recent comparative MRI studies show that the human brain has a higher relative amount of white matter in the prefrontal cortex than other primates. More connections are presumed to contribute to faster information processing, contrary to what Manger concludes for cetaceans. In fact. Manger's own data, presented in his Table 2, shows that when computing the volume of grey matter as a percentage of total brain volume, humans fall below the other primate species he lists."

Prof Manger: The CI index reveals the amount of the brain devoted to neural processing, i.e. the proportion of the brain where synapses are found - this being the neuropil. The neuropil is incredibly important in determining the potential processing power of a brain, as it is in this region of the brain that neurons communicate. By showing that for their brain size the amount of space potentially dedicated to the neuropil is lower in cetaceans than would be expected is a further indication of a brain not built for complex information processing. On top of this I demonstrated that the proportions of the cetacean neuropil are probably quite unbalanced in comparison with other mammals, being occupied more by glial processes and myelin rather than dendritic aborizations and axonal branching - another indication of a poor processor. Yes, the human is slightly lower than other primates, but the cetaceans are far lower than would be expected for their brain size, which is radically different for most mammalian species.

The Dolphin Pod: The strongest (scientific) objections to your paper seem to be coming from scientists who have collected or written about laboratory and field data concerning dolphin cognition. Although you critique some of these laboratory experiments in your paper, many argue that you failed to fully address the bulk of evidence for intelligent dolphin behavior from the current literature. You have outlined in a previous answer some ideas concerning what intelligent behavior is and how to test for it. Do you envision future papers where you may address these criticisms and offer an alternative interpretation of the current behavioral data in more detail?

I think the major problem here, and the threat perceived by many scientists (not only scientifically, but also financially), including Dr. Marino, is the fact that intelligence, measured by intelligent behaviour, is the observable expression (or lack of expression in terms of behavioural inhibition) of neural activity and processing, and of course, if the processor is not built appropriately, as indicated in my paper and the studies of many previously, then the actual ability for the production of intelligent behaviour must be missing. We cannot divorce structure from function in the way that many who study dolphin behaviour have been doing currently and for the last 50 years. In fact, even with a 50 year search for intelligence in dolphins no "smoking-gun" has appeared. I am uncertain as to the extent and usefulness of future papers dealing with the reported behaviour in dolphins and whales, as without the appropriate brain, there is no intelligent behaviour. I think the onus is now on the cetacean behaviourists to prove beyond doubt that what they are doing cannot be explained by a simpler mechanism rather than jumping to the cognitive conclusion.

The Dolphin Pod: To take one example that you mention: you pointed out that the intelligent behavior exhibited by avian species may be surprising to some, and mentioned eye-gaze following in corvids. Many would argue that eye gaze following in corvids is indeed evidence of complex cognition in these animals, as it is similarly argued for some of the primate species capable of following eye gaze. This kind of behavior has not been observed in some of the conventionally acknowledged 'less intelligent' animals like rats, or even some of the more 'intelligent' species like horses. It has, however, been shown that dolphin species exhibit gaze following behaviors similar to those observed in corvids and primates. Following from your ideas concerning the dolphin brain, what do you believe are the reasons for this specific discrepancy?

Prof Manger: My first reaction here would be to examine contextual ambiguities - those parts of any experiment that do not gel with the sensory or motor capabilities of the animals being tested. For example, given the poor eyesight and nocturnal habits of the rat, would we expect it to be an animal that follows the gaze of others? It has been shown that this type of comparison as a method of ranking intelligence is rather a poor way of doing it. In fact, the "learning sets" type of behaviour based on visual stimuli first showed that rodents were less intelligent that primates and cats, but when tested on learning sets involving olfactory stimuli, rodents performed equally well. Thus, the experimental context of these comparisons must be considered prior to making any value judgments of the relative cognitive abilities of the various species.

 

Questions Round 2 Dr. Marino

The Dolphin Pod: Could greater 'information processing' power have been an emergent property of a brain that evolved for thermoregulation?

Dr. Marino: Greater information processing power could, in principle, emerge from any number of evolutionary developments. Given what we know about brain evolution and ontogeny, however, it is difficult for me to accept that a significant proportion of the variance in intelligence in cetaceans could be due to thermoregulatory changes in the brain.

The Dolphin Pod: Is it possible that an increase in glial cells in the brain may actually indicate a brain that is better and faster at processing information? I refer to studies on rats that show an increase in the growth of glial cells for rats exposed to an enriched environment. Does this contradict Dr. Manger's claims that a high glia:neuron ratio indicates less information processing?

Dr. Marino: What we know about the role of glia contradicts Manger's claims that a high glia-neuron ratio indicates less information processing. In fact, all the evidence indicates that an increase in glial cells is correlated with more efficient and faster information processing. Here is what the scientific literature says:

1) Glia are not inert elements taking up space in the brain. Rather, they participate in the modulation of neural activity. They contribute to the complexity of neural processing in this way.

2) Glia provide myelin (otherwise known as 'white matter') for efficient neural transmission. Myelin maintains information processing rate. When brains enlarge the amount of white matter increases in order to maintain processing speed and efficiency.
Examples of what happens to neural activity when glia are lost are the de-myelinating disorders such as multiple sclerosis and many of the "dystrophies". These disorders show that glia are critical for efficient neural activity.

3) The more glia there are the larger the proportion of neuropil. Neuropil is the material outside the cell body - dendrites and fibers. The more dendrites the more complex the synaptic connectivity of the brain. Therefore, contrary to Manger's claim, a high proportion of glia is consistent with a high level of information processing complexity.

5) Recent comparative MRI studies show that the human brain has a higher relative amount of white matter in the prefrontal cortex than other primates. Is Manger prepared to assert that humans are less intelligent than monkeys?

The Dolphin Pod: Do you have any comments on Dr. Manger's response to the following question that I posed:
(The Dolphin Pod to Prof. Manger) In your opinion, what are the strongest neurological correlates of intelligence for brains in general?
(Quoting Prof. Manger): "The brain is a hierarchically organized processor of information. This spans from the molecular level, through receptor complexes, synapses, parts of neurons (such as dendrites), single neurons, clusters of neurons, nuclei and cortical areas, systems, with behaviour being the expression of this processing. Dolphin brains are mammalian brains, and as such, follow the patterns established early in mammalian evolution. For a brain to be a complex processor of neuronal information all levels of this organizational hierarchy must be functional, otherwise the brain fails. For example, in recent work with colleagues (Elston GN, Benavides-Piccione R, Elston A, Zietsch, B., Defelipe J, Manger P, Casagrande V, Kaas JH. Specializations of the granular prefrontal cortex of primates: implications for cognitive processing. Anat Rec A Discov Mol Cell Evol Biol. 2006 Jan;288(1):26-35.) we have shown that with increases in brain size in primates, the complexity of the neuron increases dramatically. This increase in complexity, and thus functionality, will have a flow on effect to higher levels of brain organization, and thus result ultimately in more complex behaviour. There are too many examples within the brains of cetaceans that violate the evolutionary patterns found in other mammals. These are listed in the paper, but include:

Low cell density
Lack of layer 4
Thin thickness for brain size
Low number of cortical areas
No/inordinately small pre-frontal cortex
High glia:neuron ratio
Low corticalization index
Small and poorly differentiated hippocampus
Unbalanced proportion of elements of the neuropil
A majority of poorly differentiated and aspinous neurons

There are just too many features at several structural levels of the dolphin brain that are not organized in a manner that indicates normal neural processing of information, thus the hierarchy typical to mammals fails. Any level of this hierarchy can become more or less complex during evolution. Increases in complexity will lead to increased behavioural sophistication and vice versa. All levels of neural organization must be investigated. Size can be important, as allometric increases in overall brain size may cause spandrels in complexity at lower levels of organization and thus increased complexity in neural processing, and this may indeed be found in primates and other species, but there is no evidence for this in cetacean species. A somewhat convoluted answer, but in brief, the whole shebang must be working, a weak link causes failure."

Dr. Marino: The main point that Manger misses is this - and it's a big one. Cetacean brains have been on an independent evolutionary trajectory for close to 55 million years. During that period the dolphin brain evolved a unique combination of features. The result of this process is that one cannot readily make simple comparisons between cetacean brains and the brains of other mammals without taking this divergent evolutionary history into account.

With that said, let's visit each of the features of the cetacean brain that Manger asserts is an indication of low information processing complexity.

1) Low cell density - the cell density in the dolphin brain is exactly what is expected for a brain of such a large size. Cell density decreases with absolute brain size in mammals. It must in order to maintain other properties of neural transmission. So cell density tells you nothing.

2) Lack of layer 4 - the presence of a granularized layer 4 in primates does not imply that this is the way cortical complexity is achieved in all mammals. The ancestral evolutionary lines that eventually produced primates and cetaceans were separated by about 95 million years. The closest cetacean relative is an ungulate but the ancestors of ungulates and cetaceans split off over 55 million years ago. So what are the chances that cetacean brains - so isolated in time and ecology from other mammals - would become complex in exactly the same way primate or other mammal brains would.
Here's an example. Dolphins echolocate by sending high frequency clicks out of their forehead and receiving the echoes with their lower jaw which mechanically conducts the sound to the middle ear. So dolphins have evolved a completely different way to receive and conduct acoustical input from humans and other mammals (including other echolocating mammals like bats). This shows that extremely different and complex ways of processing information can indeed occur - given enough time.

3) Thin cortex(?) for brain size - the dolphin neocortex may be thin but it possesses a surface area that far exceeds the human brain. So, without any way to functionally anchor this characteristic to computational complexity - it isn't clear at all that a thin highly convoluted cortex processes less information than a thicker less convoluted cortex. The opposite argument can just as readily be made. Take your pick!

4) Low number of cortical areas - This claim is based on nonexistent data. No one (and that includes Paul Manger!) knows how many functional cortical areas exist in the dolphin brain.

5) Small prefrontal cortex - This point is so mired in a concrete way of thinking about neuroanatomy that one barely knows where to begin. Manger surely cannot seriously claim that the frontal lobe analog in the dolphin brain needs to be - literally - in the front!

6) High glia-neuron ratio - Please see my more detailed response above. If anything, high glia:neuron ratio is more indicative of information processing complexity than not.

7) Low CI - Manger's analyses of CI are confounded with body size, which he does not take into account. Therefore, his claims about low CI are based on flawed analyses.

8) Small hippocampus - Only certain parts of the hippocampus in cetacean brains are reduced. Other components, such as the amygdala, are well developed. Other areas that are related to the hippocampal formation, such as the limbic lobe and insular cortex, are extremely elaborated in cetacean brains. Cetacean brains also possess a paralimbic lobe that is not found in other mammal brains.

More importantly, despite the fact that Manger wants to claim that dolphin memory is weak because of a small hippocampus, he cannot account for the prodigious body of empirical literature showing that dolphins possess quite exquisite and sophisticated memory capacities. Studies by Herman and colleagues have shown that both auditory memory (memory for things heard) and visual memory (memory for things seen) are well developed and robust in dolphins. These studies deal with short-term or "working memory"-processing new information and retaining it in conscious memory. Manger overlooks work by Xitco and colleagues that has revealed the dolphin's superb ability to remember the spatial locations of named structures in its extensive habitat. And mysticetes display migration patterns that can best, if not only, be explained by their possession of a highly sophisticated spatial long-term memory capacity.

The bottom line is that cetaceans have excellent memory capacities despite a small hippocampus. The behavioral literature cannot be dismissed because the neuroanatomical substrate of memory in cetaceans is not yet understood. Obviously there is another part of the cetacean brain that has taken over the function of memory.

9) Unbalanced elements of neuropil - If Manger is referring to the high proportion of glial cells then that claim has already been responded to. There is no evidence for an "unbalanced neuropil" in cetaceans.

10) Poorly differentiated cortex - Manger's view of the cetacean cortex is so out of date that he cites studies from 1879. Yet he ignores recent work (that he should be well aware of) showing that the cetacean neocortex is, in fact, highly differentiated and complex.
What is so puzzling is that some of his own work has shown that dolphin cortex is differentiated.

 

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Herman's Dolphin Prodigies
13 December 2019

Herman's Dolphin Prodigies

Last week, we produced a podcast titled ‘the dim dolphin controversy’. You may recall from this episode that many scientists referred to the work of Dr. Louis Herman’s research lab when citing examples of intelligent dolphin behavior. In this week’s episode, we will learn what Dr. Herman’s research has taught us about dolphin behavior and why these studies are considered by many to be proof positive that dolphins are smarter than the average goldfish. In fact, even smarter than the above-average goldfish.

Last week, we produced a podcast titled 'the dim dolphin controversy'. You may recall from this episode that many scientists referred to the work of Dr. Louis Herman's research lab when citing examples of intelligent dolphin behavior. In this week's episode, we will learn what Dr. Herman's research has taught us about dolphin behavior and why these studies are considered by many to be proof positive that dolphins are smarter than the average goldfish. In fact, even smarter than the above-average goldfish.

Dr. Herman has been researching the behavioral abilities of dolphin at the Kewalo Basin Marine Mammal Laboratory in Honolulu Hawaii since the early 1970's. This research lab is famous for their studies of language comprehension by dolphins - in these studies, captive dolphins were taught how to use an artificial language system meant to test their ability to understand and use symbols to communicate. The results of these studies have been considered by many to be nothing short of incredible. But, these language studies are only the tip of the iceberg: many other groundbreaking discoveries have been produced from Dr. Herman's lab. In this podcast, we will look into some of these important studies in more detail. I have organized the top set of results into a list that I call:

Dr. Herman's Top 5 Most Remarkable Dolphin Discoveries

Watch Herman's Dolphin Prodigies in Action

At number 5, we have 'behavioral mimicry'
Dr. Herman's dolphins are able to imitate the movements of their trainers. When requested by a trainer to copy their movements, a dolphin will imitate a whole variety of movements performed by the trainer including turning a pirouette, or lifting arms and legs. Obviously, dolphins don't have arms or legs, so they used their pectoral fins or flukes as analogous body parts. Dolphins are also fantastic vocal mimics - able to accurately copy a large variety of sounds. Other than humans, there do not appear to be any animals, as yet studied, that are capable of imitating body movements in this way.

Coming in at number 4, we have 'dolphins on TV'
Most animals have a very difficult time interpreting what they see on TV as analogous to what they perceive in the real world. Even chimpanzees don't quite understand what is happening when they are first exposed to television images. After some training, however, they will eventually learn to perceive television images in a way similar to human beings. In contrast, dolphins seem to 'get' TV from their first exposure. Dr. Herman placed a TV in the underwater viewing window of the dolphins' tank which displayed a researcher giving gestural commands to the dolphin. That is, the researcher was on TV and the dolphins were watching the TV. The dolphin understood these commands right away. This ability is interesting if you consider that the image on the television that the dolphin saw was a tiny 2-D black and white representation of a human being - quite different from the real thing. The fact that a dolphin could figure out what this image was all about reveals that they have a rather complex visual recognition system and an ability to interpret distorted visual stimuli as representing something from the real world. (Watch Dr. Ken Marten describe his experiments with dolphins and TV )

Third in our list is 'awareness of one's own body parts'
Researchers at Herman's lab assigned gestural symbols to different parts of the dolphin's body. The trainers would then use these gestures to ask a dolphin to do different things with their various body parts. For example, touch the Frisbee with your dorsal fin. This task didn't cause the dolphins much trouble at all, likely revealing that they are aware of their own body to some extent.

Coming in at number 2, 'understanding pointing gestures'
Researchers gave dolphins commands to perform on objects, but instead of naming the objects, the researchers simply pointed to the objects. Dolphins were able to understand the reference of the human pointing gesture in a variety of circumstances, and what's more, the dolphins could do it without being expressly trained to understand pointing. This ability is rare in the animal kingdom - not even chimpanzees are able to understand pointing gesturess this easily. What's even stranger; try thinking about why it is a dolphin understands a pointing gesture when dolphins don't even have arms! But, that's a subject for future podcasts…

And, the most astonishing discovery of all making the top of our list: 'artificial language comprehension'
In an attempt to find out what animals are capable of understanding when it comes to human language, many researchers throughout the years have developed artificial language systems and tried to teach them to animals. Gorillas, chimps and bonobos (aka the pygmy chimp) have all had some success manipulating artificial language systems. Dr. Herman demonstrated that dolphins were also capable of something similar. Dolphins were taught gestures that represented words and actions with which they were able to carry out instructions. What's really interesting about this study was that word order was used to communicate different kinds of actions. For example, the gestural sequence Surfboard Person Fetch means, "take the person to the surfboard," whereas the sequence Person Surfboard Fetch means the opposite, -"take the surfboard to the person." - something that the dolphins had no trouble with.

So, there you have it: Dr. Herman's Top 5 Most Remarkable Dolphin Discoveries. Many scientists feel that these examples of clever behavior prove that dolphins are indeed intelligent animals, or at the very least in scientific terms: "highly cognitive".

If you would like to learn more about these five studies by Dr. Herman and his team of associates, then please visit the website of The Dolphin Institute: at www.dolphin-institute.org.

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Dolphin breathing - it's the thought that counts
13 December 2019

Dolphin breathing - it's the thought that counts

In the dolphin brain, breathing is controlled consciously – that means that a dolphin has to think about every breath it wants to take before it takes it. Learn how dolphins sleep, and still manage to control their breathing.

Your breathing is controlled by parts of your brain called the medulla oblongata and the pons - they are located deep in your brain-stem down at the base of your brain. These little guys are in control of a lot of very important things that you do, including keeping your heart beating. And, you have them to thank every time you sneeze, swallow or blink - they control it all! Every second of every hour of every day the medulla oblongata and the pons are working hard to make sure that your body keeps trucking along.

They never sleep - even when other parts of your brain do. We can, of course, take over conscious control of our own breathing - try it by holding your breath while you listen to this podcast. You have just relieved the medulla oblongata and the pons of their breathing duties. But, they are poised and ready to resume control of your breathing whenever you decide need them to. Isn't it nice to know that they will always be there for you? Here's an unsettling fact: for dolphins, the medulla oblongata and the pons do NOT control their breathing. Ever! In the dolphin brain, breathing is controlled consciously - that means that a dolphin has to think about every breath it wants to take before it takes it. This makes a lot of sense really - since dolphins spend their entire lives underwater, they need to think about and time exactly when they go up for air, so there is no real need for an involuntary breathing mechanism. But, that raises the following question: if a dolphin has to be awake and thinking about every breath it takes, how on earth do they sleep? A major flaw with this conscious breathing system is that if a dolphin ever really did fall asleep, it would simply stop breathing and die. The solution: never fall asleep! Or, at least in the case of dolphins, never sleep both halves of your brain at the same time. Dolphins, just like humans, have brains divided into two halves or 'hemispheres'. Over the years, they have evolved a neat little trick where they can put one half of their brain to sleep while the other half stays awake. The awake-half will then be able to control breathing and swimming, and other behaviors. For humans and dolphins, each eye is wired to the brain on the opposite side of the head. So the left eye is controlled by the right half of the brain and vice versa. When dolphins are resting, they sometimes close one eye - if you see a resting dolphin with her left eye closed, you can assume that the right side of her brain is asleep. But, the left half of her brain will be awake; controlling her breathing and making sure she doesn't suffocate or drown. And, quite literally, keeping one eye out for sharks. When dolphins rest, they usually swim quite slowly not too far from the surface, making it easier to swim up for a breath. Each brain half will get a chance to rest for a while before swapping with the other half. Generally, dolphins will rest like this for about 8 hours a day. Luckily for dolphins, the medulla oblongata and the pons are still in control of their heartbeat. Imagine how tiring it would be if you had to think about making your heart beat all day long. Some yoga masters claim to be able to control their heartbeat, but as for me - well, I am glad I am neither a dolphin nor a yoga master; I am happy to let the medulla oblongata and the pons run the whole show when I am asleep. Thanks guys! I'm also pretty happy I don't have to worry about sharks nibbling on me when I decided to take a nap

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Newsflash: Japanese Dolphin Drive Hunts Day of Protest
13 December 2019

Newsflash: Japanese Dolphin Drive Hunts Day of Protest

Today, September 20th 2006, marks an international day of protest initiated by a consortium of scientists against the annual Japanese dolphin drive hunts. The goals of the campaign are to raise public awareness of the dolphin drive hunts, and to boost measurable support through the group’s website petition which currently includes over 22,000 signatures, including many noted marine mammal scientists. To learn about this campaign, please visit their website at www.actfordolphins.com

Read and sign the Act For Dolphins petition: Act For Dolphins

 

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Know a dolphin's body parts
13 December 2019

Know a dolphin's body parts

Here is a news flash: dolphins do not have arms or legs! OK, OK, so that is hardly news. Surely everyone knows that dolphins have flippers instead of arms. Or, is it flippers instead of legs? Or, are they called fins? Fins, flippers… uh oh, what exactly are all those special dolphin appendages called?

This sounds like a job for "Dolphin Anatomy Terminology Man".
Wherever there is improper vocabulary use, he'll be there…

'Hey mommy, look at the dolphin's snout' - 'Stop right there, young man, that's not called a snout: that is the dolphin's rostrum. And remember; accurate anatomical terminology is cool'

Wherever layman language hinders the proper identification of body parts, he'll be there:

'I heard that a dolphin breathes through a nose on the top of its head' - 'No son, it's not called a nose, it is in fact termed a blowhole. And remember; accurate anatomical terminology is cool'

OK, I have to admit that Dolphin Anatomy Terminology Man sounds desperately boring as far as superheroes go. So, let's put him back on the shelf, and I'll provide you with a 'super' easy list of unique body parts that dolphins have:

First, let's start with this pesky fin/flipper problem. The word 'flipper' is a kind of general term that some people use to describe many different parts of a dolphin's body, but correct terminology for a dolphin's body does not make use of the word flipper at all. Those flippers on the side of the dolphin's body are actually called pectoral fins or, for those scientists in a hurry; pec fins. The word 'pectoral' comes from the Latin word meaning chest or breast. So, pec fins are, in a way, chest fins.

Interestingly, the dolphin pectoral fin is homologous to our own hand and arm bones. It you took an X-ray of the dolphin pectoral fin, you would see shortened bones that resembled our fingers, forearm, and upper arm.

The fin on the top of the dolphin's body is called the dorsal fin. The word 'dorsal' comes from another Latin word meaning 'back'. Not all dolphin species have a visible dorsal fin - in the absence of a distinct fin, this area is called the dorsal ridge.

A dolphin's tail is actually made up of a variety of different parts. The tail stock is called the peduncle. The peduncle flattens out into two halves which are called flukes. The flat end of the tail consists of two flukes - the left fluke and the right fluke. Where the two flukes meet in the middle is usually called the median notch.

As you can see, there are in fact no flippers on a dolphin at all!

Heading underneath the dolphin, you will notice that they don't have any visible genitalia. For male dolphins, the genitals are tucked up safe and sound inside, but sometimes make an appearance through an area of the dolphin's belly called the genital slit. Female dolphins have two slits on either side of their genital slit where the mammary glands can be found.

Heading back to the front end of the dolphin, we are faced with problem of what to call the dolphin's long 'nose'. Many people call this long "nose", consisting of the lower and upper jaw, a 'beak' or 'snout', but its proper name is in fact 'rostrum', as Dolphin Anatomy Terminology Man pointed out earlier. Although a variety of words will crop up to describe the rostrum (like beak), and none of them are incorrect per se, you will always be correct if you refer to a dolphin's beak as a rostrum. Dolphins that don't have a distinct protruding rostrum (like the killer whale) are sometimes described as having a 'blunt' rostrum.

Sticking with the head, the word 'melon' is used to describe the rounded front part of a dolphin's forehead. The melon contains a fatty substance nicknamed "acoustic fat" that the dolphin uses to direct their echolocation beam. This acoustic fat has the same density as seawater, making it easy for sound waves to pass through the melon into the water. Interestingly, this fat also fills the lower jaw of the dolphin. Dolphins use their lower jaw to receive sound waves and direct them toward their middle ear - in other words, a dolphin hears through its lower jaw!

The hole on the top of a dolphin's head through which it breathes is called the blowhole. Here is a little extra fact: dolphins can't breathe through their mouths - they can only breathe through their blowholes! Their trachea and esophagus are completely separate.

So, that about covers all of the terminology that you need to know in order to describe the unique external body parts found in dolphins. Here are those terms again:

Pectoral fins
Dorsal fin
Peduncle
Fluke
Median notch
Genital slit
Rostrum
Melon
Blowhole

If you learn to use those words when talking about a dolphin's body, you will sound like a real dolphin expert! Things do get a bit more complicated once we start talking about what you can find inside a dolphin.

'If you require my assistance, do not hesitate to ask'

Yes well, thank you Dolphin Anatomy Terminology Man - I'll keep that in mind for future episodes.

Oh boy…

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How to identify individual dolphins
13 December 2019

How to identify individual dolphins

For scientists studying wild dolphin populations, being able to identify individual dolphins is a vital component of their research. In this week’s episode, learn how scientists are able to tell one dolphin from another.

Have you ever had that feeling where you are talking to someone at a party and you are sure that you have met them before but you just can’t seem to place them? Did you meet them at your cousin’s wedding last summer maybe? Did they go to elementary school with you perhaps? This can be frustrating. Now take that feeling and multiply it by about a million, and you will have a pretty good idea what it feels like as a scientist trying to identify individual dolphins. Dolphins, unlike humans, rarely wear nametags, they never style their hair into a unique coiffure that make them easy to pick out in a crowd, and you won’t ever be able to recognize a dolphin because of the shoes it is wearing.

For scientists studying wild dolphin populations, being able to identify individual dolphins is a vital component of their research. Studies gathering information about individual dolphins are used for research on population size estimations, migration patterns, social structure, group movements, life histories, and behavior. For example; researchers may be interested in learning how often individuals within a group interact with other individuals – patterns of association. Scientists may want to learn what kinds of behaviors are being produced by the adults, the juveniles, the males, the females and so on – all of this requires the scientist to know and recognize which individual dolphins they are observing.

To do this, researchers rely on a variety of identification or “ID” techniques. The most popular technique is photographing the dorsal fin of the dolphin as it breaks the surface to breathe – this is often called photo-ID. Dorsal fins can function a lot like human fingerprints – the notches and nicks along the edge of the fin allow researchers to recognize and categorize individuals. This technique is very handy for species that don’t really like the presence of boats – researchers can use telephoto lenses to capture a picture of a dorsal fin from a greater distance. There is even some pretty fancy computer software that will help researchers search through scanned dorsal fin images to try and match photographs to the fins of previously identified dolphins. Some dolphin species will have natural markings or coloring patters that are visible when they surface, and these can be used for ID as well.

For those scientists able to actually enter the water to film or photograph wild dolphins under water, or for those using an underwater camera from their boat, it is possible to identify dolphins based on a variety of body features. Sometimes deformities like missing fins or a prominent under-bite can be used to ID individuals. Wild dolphins accumulate a huge variety of scars and marks throughout their lifetime: everything from shark bites to cuts and scratches from contact with rocks, and even injuries resulting from fights with other dolphins. If the dolphin is unlucky enough to have a nasty scar, or a chunk missing from its fluke, a scientist will have a relatively easy time re-identifying this individual based on underwater video or still photos. For the Indo-Pacific bottlenose dolphins that the Dolphin Communication Project studies around Mikura Island, scars from shark bites are all too common. One shark in particular, the cookie cutter shark, is known for taking a nasty circular bite out of the dolphin’s flesh – it leaves a prominent scar that makes it very easy to recognize specific individuals. For images of cookie cutter and other shark bite scars from the Mikura dolphins, check out The Dolphin Pod website for links.

The trick is of course finding scars that are going to stick around for a few years – many species of dolphins are covered in ‘rake marks’ – these are shallow scars caused by the teeth of other dolphins, and they occur when dolphins are fighting or playing with each other. Since rake marks are often shallow, they will only be visible for a few weeks to a few months, and are not a reliable way to identify individuals over longer periods of time (i.e., between years). Some species of dolphins, like spotted dolphins, develop spots as they age. If researchers remain vigilant and keep clear records of the development of these spots over years, these distinctive spot patterns will allow them to reliably recognize individuals.

The key to being able to identify individual dolphins is keeping good records – well organized photographic and video records are invaluable. Many scientists will keep a book with sketches of individual dolphins that can be easily updated as dolphins accumulate new scars. Individual dolphins are typically assigned names and/or numbers. To learn about some of the research groups working on identifying individual dolphins as part of their research, visit The Dolphin Pod website for links. There is even a link to an online test to see how skilled you are at identifying individual dolphin dorsal fins.

http://www.cbmwc.org/research/photo_id_interact.asp

Of course, these kinds of ID techniques could be used to avoid the predicament described at the start of this episode. Imagine how handy it would be if, when you came across that person at the party who you just couldn’t place, you pulled out your photo-ID book and flipped through until you found out who they were. “Ah yes, your name is Todd Johnson – I lasted sighted you on June 15 at the Henderson’s housewarming party. You were seen associating with an adult female and two juvenile males. How have you been, Todd?

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