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
Baleen whale SeaWorld San Diego and, after 14 months, was released because it got too big to take care of. Reaching and , J.J. was the largest creature to be kept in captivity. The Mito Aquarium in Numazu, Shizuoka, Japan, housed three minke whales in the nearby bay enclosed by nets. One survived for three months, another (a calf) survived for two weeks, and another was kept for over a month before breaking through the nets. Baleen whale Baleen whales (systematic name Mysticeti), known earlier as whalebone whales, form a parvorder of the infraorder Cetacea (whales, dolphins and porpoises). They are a