How can you tell how old a dolphin is?


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. To see images of dolphin teeth showing these growth layers, visit

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


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