The beluga or white whale, Delphinapterus leucas, is an Arctic and sub-Arctic cetacean. It is one of two members of the family Monodontidae, along with the narwhal, and the only member of the genusDelphinapterus. This marine mammal is commonly referred to simply as the melonhead, beluga or sea canary due to its high-pitched twitter.
It is adapted to life in the Arctic, so has a number of anatomical and physiological characteristics that differentiate it from other cetaceans. Amongst these are its unmistakable all-white colour and the absence of a dorsal fin. It possesses a distinctive protuberance at the front of its head which houses an echolocation organ called the melon, which in this species is large and plastic (deformable). The beluga’s body size is between that of a dolphin’s and a true whale’s, a male can be up to 5.5 m (18 ft) long and it can weigh up to 1,600 kg (3,500 lb). This whale has a stocky body; it has the greatest percentage of blubber. Its sense of hearing is highly developed and it possesses echolocation, which allows it to move about and find blowholes under sheet ice.