The beluga whale 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 genus Delphinapterus. 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 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, with males growing up to 5.5 m (18 ft) long and weighing up to 1,600 kg (3,500 lb). This whale has a stocky body; A large percentage of its weight is blubber. Its sense of hearing is highly developed and it possesses echolocation, which allows it to move about and find blowholes under sheet ice.
Belugas are gregarious and form groups of up to 10 animals on average, although during the summer, they can gather in the hundreds or even thousands in estuaries and shallow coastal areas. They are slow swimmers, but can dive to 700 m (2,300 ft) below the surface. They are opportunistic feeders and their diets vary according to their locations and the season. They mainly eat fish, crustaceans, and other deep-sea invertebrates.
The majority of belugas live in the Arctic and the seas and coasts around North America, Russia and Greenland; their worldwide population is thought to number around 150,000. They are migratory and the majority of groups spend the winter around the Arctic ice cap; when the sea ice melts in summer, they move to warmer river estuaries and coastal areas. Some populations are sedentary and do not migrate over great distances during the year.
The native peoples of North America and Russia have hunted belugas for many centuries. They were also hunted commercially during the 19th century and part of the 20th century. Whale hunting has been under international control since 1973. Currently, only certain Inuit and Alaska Native groups are allowed to carry out subsistence hunting of belugas. Other threats include natural predators (polar bears and killer whales), contamination of rivers, and infectious diseases.
From a conservation perspective, the beluga was placed on the International Union for Conservation of Nature's Red List in 2008 as being "near threatened"; the subpopulation from the Cook Inlet in Alaska is considered Critically Endangered and is under the protection of the United States' Endangered Species Act. Of seven Canadian beluga populations, the two inhabiting eastern Hudson Bay and Ungava Bay are listed as endangered.
Belugas are one of the cetaceans most commonly kept in captivity in aquariums and wildlife parks in North America, Europe, and Asia; they are popular with the public due to their colour and expression.