|
| unranked_subordo = Cetacea | unranked_superfamilia = Odontoceti | familia = Delphinidae | genus = ''Orcinus'' | genus_authority = Fitzinger, 1860 | species = ''O. orca'' | binomial = ''Orcinus orca'' | binomial_authority = (Linnaeus, 1758) | synonyms = ''Orca gladiator'' | range_map = Cypron-Range Orcinus orca.svg | range_map_alt = A world map shows killer whales are found throughout every ocean, except parts of the Arctic. They are also absent from the Black and Baltic Seas. | range_map_caption = ''Orcinus orca'' range (in blue)}} The killer whale (''Orcinus orca''), also referred to as the orca whale or orca, and less commonly as the blackfish or grampus, is a toothed whale belonging to the oceanic dolphin family, of which it is the largest member. Killer whales are found in all oceans, from Arctic and Antarctic regions to tropical seas. Killer whales have a diverse diet, although individual populations often specialize in particular types of prey. Some feed exclusively on fish, while others hunt marine mammals like pinnipeds, and even large whales. They have been known to attack baleen whale calves. Killer whales are regarded as apex predators, lacking natural predators. Killer whales are highly social; some populations are composed of matrilineal family groups which are the most stable of any animal species. Their sophisticated hunting techniques and vocal behaviors, which are often specific to a particular group and passed across generations, have been anthropomorphically described as manifestations of culture.〔 The IUCN currently assesses the orca's conservation status as data deficient because of the likelihood that two or more killer whale types are separate species. Some local populations are considered threatened or endangered due to prey depletion, habitat loss, pollution (by PCBs), capture for marine mammal parks, and conflicts with fisheries. In late 2005, the "southern resident" population of killer whales that inhabits British Columbia and Washington state waters were placed on the U.S. Endangered Species list. Wild killer whales are not considered a threat to humans, but there have been cases of captive orcas killing or injuring their handlers at marine theme parks.〔(【引用サイトリンク】title=Footage shows killer whale attack at SeaWorld | Video )〕 Killer whales feature strongly in the mythologies of indigenous cultures, with their reputation ranging from being the souls of humans to merciless killers. ==Taxonomy and evolution== ''Orcinus orca'' is the only recognized extant species in the genus ''Orcinus'', one of many animal species originally described by Linnaeus in 1758 in ''Systema Naturae''. Konrad Gessner wrote the first scientific description of a killer whale in his "Fish book" of 1558, based on examination of a dead stranded animal in the Bay of Greifswald that had attracted a great deal of local interest.〔(Zum Wal in der Marienkirche ) (in German). St. Mary's Church, Greifswald. Retrieved February 16, 2010〕 The killer whale is one of 35 species in the oceanic dolphin family, which first appeared about 11 million years ago. The killer whale lineage probably branched off shortly thereafter. Although it has morphological similarities with the pygmy killer whale, the false killer whale and the pilot whales, a study of cytochrome b gene sequences by Richard LeDuc indicated that its closest extant relatives are the snubfin dolphins of the genus ''Orcaella''.〔 〕 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「Killer whale」の詳細全文を読む スポンサード リンク
|