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| unranked_subordo = Cetacea | unranked_superfamilia = Odontoceti | familia = Monodontidae | genus = ''Delphinapterus'' | genus_authority = Lacépède, 1804 | species = ''D. leucas'' | binomial = ''Delphinapterus leucas'' | binomial_authority = (Pallas, 1776) | range_map = Cetacea range map Beluga.png | range_map_caption = Beluga range | status = NT | status_system = iucn3.1 | status_ref = 〔 }} 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.〔 Harris, Patricia; Lyon, David; (8 April 2007) Boston Globe ''(Enter close quarters: colonial to nuclear subs. )'' Section: Travel; Page 8M.〕 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 long and weighing up to . 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. 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 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. ==Taxonomy== The beluga was first described in 1776 by Peter Simon Pallas.〔 It is a member of the Monodontidae family, which is in turn part of the toothed whale suborder.〔 The Irrawaddy dolphin was once placed in the same family; recent genetic evidence suggests these dolphins belong to the Delphinidae family. The narwhal is the only other species within the Monodontidae besides the beluga. A skull has been discovered with intermediate characteristics supporting the hypothesis that hybridization is possible between these two families. The name of the genus, ''Delphinapterus'', means "dolphin without fin" (from the Greek δελφίν (''delphin''), dolphin and απτερος (''apteros''), without fin) and the species name ''leucas'' means "white" (from the Greek λευκας (''leukas''), white). The Red List of Threatened Species gives both beluga and white whale as common names, though the former is now more popular. The English name comes from the Russian белуха (''belukha''), which derives from the word белый (''bélyj''), meaning "white".〔 Note that the name ''beluga'' in Russian refers to a totally unrelated species, see Beluga (sturgeon). The whale is also colloquially known as the sea canary on account of its high-pitched squeaks, squeals, clucks, and whistles. A Japanese researcher says he taught a beluga to "talk" by using these sounds to identify three different objects, offering hope that humans may one day be able to communicate effectively with sea mammals. A similar observation has been made by Canadian researchers, where a beluga which died in 2007 "talked" when he was still a subadult. Another example is NOC, a beluga whale that could mimic the rhythm and tone of human language. Beluga whales in the wild have been reported to imitate human voices. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「beluga whale」の詳細全文を読む スポンサード リンク
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