The narwhal is perhaps one of the most easily recognizable of all cetaceans thanks to their distinctive long tusks. Learn more about the narwhal’s tusks and what it is used for in this week’s episode.
Mr. Narhwal is a cartoon character based on a unique species of cetacean called (funnily enough) the narwhal (pronounced nar-wall or nar-whale). The narwhal is perhaps one of the most easily recognizable of all cetaceans thanks to their distinctive long tusks. In fact, narwhals and their peculiar tusks have been famous for many centuries, long before Mr. Narwhal starred opposite Will Farrell. For many centuries, narwhal tusks were sold and marketed as unicorn horns; people once thought (and maybe still do) that they contained magical powers.
I bet there is a lot about narwhal tusks that you may already know, like:
That only male narwhals have tusks
That narwhals have just one tusk, not two
That narwhals fight using their tusks like swords
Well, I’m sorry to say that all of these facts are wrong – myths really. About as true as the claim that narwhals’ tusks are magical. I’ll explain why in a moment, but first, I should mention that even though this is a podcast that is intended to be about dolphins, narwhals are not necessarily considered dolphins. They are placed in the scientific family monodontidae together with their cousin the beluga whale, and not in the family delphinidae where dolphin species are found. Although, like the species in the family delphinidae, they are in the suborder odontoceti or toothed cetaceans, so narwhals are undeniably closely related to dolphins. [maybe we should call our podcasts “all things cetacean”] If this seems a bit confusing, I recommend that you listen to the Dolphin Pod episode from August 29, 2006, titled “Is that a dolphin or a whale” – that episode should help clear things up concerning the terms ‘dolphin’ and ‘whale’. And, one last taxonomical tidbit: the genus and species of the narwhal is Monodon monoceros which translates into: ‘one tooth, one horn’. Oh, and for those of you interested in etymology – the word narwhal comes from Old Norse roots; ‘nar‘ means ‘corpse’, and ‘whal’ means ‘whale’ – so the term ‘narwhal’ could be translated as ‘corpse whale’. Some researchers believe that this cetacean is called narwhal because its coloring is grey-whitish, giving it the appearance of a drowned human corpse. Although others think that it was named this because of the narwhal’s habit of floating belly up on the surface of the ocean for minutes at a time. The Inuit name for the narwhal is (and please excuse my terrible pronunciation) Qilalugaq qernartaq meaning “the one that points to the sky” – a reference to the narwhal’s habit of sticking its head straight out of the water with its tusk pointed straight up.
Now, let’s turn back to the 3 modern myths about the narhwal’s tusk that I mentioned earlier. First, the myth that only male narwhals have tusks. In fact, females too sometimes develop tusks, although their tusks are usually much shorter, straighter and whiter than that of the males. The tusk itself is actually the left tooth of the narwhal that grows out of their top jaw. Each narwhal has only two teeth; the right tooth will (usually) stay imbedded in their jaw, whereas the left tooth pokes through the rostrum, turning into the signature tusk, which can grow up to 3 meters or 10 feet in length. I say “usually” because, unlike what is commonly believed, some narwhals do in fact have two tusks. Skulls of narwhals with both left and right teeth erupted into two tusks have been found (which completely dispels myth number two).
This leads us to the truth about myth number three, which was the idea that narwhals use their tusks in sparing matches, a behavior that has been labeled ‘tusking’. Scientists used to think that these fights were a way for males to duke it out for access to females, with the simple rule that the largest tusk gets the girl. Researchers have found however that this isn’t the case – narwhals rarely engage in fierce tusk bashing competitions, opting for more of a soft and gentle rubbing of the tusks. The Inuit people, who probably know more about narwhal behavior than even the most experienced narwhal researchers, also report that violent tusking duels are rare. When narwhals do get involved in tusking, it is usually quite subdued. So, if the tusk isn’t used for fighting, then what might it be used for? Well, that question has been one that has plagued scientist for decades. Aside from the hypothesis about sword-fighting, scientist have also suggested that the tusk might be used to:
help in echolocation
shed excess body heat
poke the seabed for food
and defend themselves from predators
But, it was a recent scientific discovery that has finally shed some light on the mysterious nature of the narwhal tusk. This discovery is a direct result of the curious mind of a mild-mannered dentist from Connecticut: Dr. Martin Nweeia. It makes sense if you think about it – who better to figure out the purpose behind a strange tooth than a dentist? In 2000, Dr. Nweeia was struck with a sudden need to know what on earth the narwhal’s giant tooth was all about. He turned his passion for the mystery of the narwhal tusk into a full blown research expedition. Helped by colleagues at the National Institute of Standards and Technology, the Canadian Department of Fisheries and Oceans, the Paffenbarger Research Center, and the Harvard School of Dental Medicine among others, Dr. Nweeia ran a series of tests on narwhal tusks, as well as some field experiments, and made the following startling discovery:
The narwhal’s tusk is filled with millions of tiny nerve endings that find their way right to the tusk’s surface. This is a very strange way for a tooth to be structured. Think about your own teeth for a second: if you have ever chipped a tooth or gotten a cavity, you know what it feels like to have a nerve ending in your tooth exposed to the air. Now imagine having millions of nerve endings exposed like this in a 3 meter tooth sticking out of your head! That is, in fact, exactly what a narwhal’s tusk is all about. This means that the narwhal’s tusk is capable of sensing very subtle changes in temperature, pressure, salinity and who knows what else! In short: the narwhal’s tusk is a sensory organ! Knowing how sensitive the tusk must be, it no longer makes any sense to suggest that it is used for fighting, bashing, smashing, spearing, poking, or stabbing. But, the scientists involved in this study are not sure exactly what the tusks are sensing; possibly, narwhals hold their tusks out of the water to sense changes in air pressure – like a barometer that can predict changes in the weather. That is only one of many possible uses – the truth is, the search for the real purpose of the narwhal’s tusk is still ongoing. Science has much to learn about the narwhal – the more we learn, the more we can dispel the myths. But in the case of the narwhal’s bizarre tusk that may act as a giant tooth barometer… well, sometimes truth is indeed stranger than fiction.