Toothed whale melon consists of fat, and the skull of any such creature containing a melon will have a large depression. The melon size varies between species, the bigger it is, the more dependent they are on it. A beaked whale, for example, has a small bulge sitting on top of its skull, whereas a sperm whale's head is filled mainly with the melon. Bottlenose dolphins have been found to have signature whistles unique to a specific individual. These whistles are used for dolphins to communicate with one another by identifying an individual. It can be seen as the dolphin equivalent of
Bowhead whale organ provides a mechanism of cooling for the whale (which is normally protected from the cold Arctic waters by or more of fat). During physical exertion, the whale must cool itself to prevent hyperthermia (and ultimately brain damage). It is believed that this organ becomes engorged with blood, causing the whale to open its mouth to allow cold seawater to flow over the organ, thus cooling the blood. Bowhead whales are not social animals, typically travelling alone or in small pods of up to 6. They are able to dive and remain submerged underwater for up to an hour. The