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The toothed whales (systematic name Odontoceti) form a parvorder of the artiodactyl infraorder Cetacea, including sperm whales, beaked whales, dolphins, and porpoises. As the name suggests, the parvorder is characterized by the presence of teeth rather than the baleen of other whales. There are 73 species of toothed whale. They are thought to have split from baleen whales, parvorder Mysticeti, around 34 million years ago. Whales and dolphins, the paraphyletic groups of cetacea, as well as porpoises, belong to the clade Cetartiodactyla with even-toed ungulates; their closest living relatives are the hippopotamuses which diverged about 40 million years ago. Toothed whales range in size from the and vaquita to the and killer whale. Several species of odontocete exhibit sexual dimorphism, in that the females are larger than males. They have streamlined bodies and two limbs that are modified into flippers. Some can travel at up to 20 knots. Odontocetes have conical teeth designed for catching fish or squid. They have well-developed hearing, that is well adapted for both air and water, so much so that some can survive even if they are blind. Some species are well adapted for diving to great depths. Almost all have a layer of fat, or blubber, under the skin to keep warm in the cold water, with the exception of river dolphins. Toothed whales consist of some of the most widespread mammals, but some, as with the vaquita, are restricted to certain areas. Odontocetes feed largely on fish and squid, but a few, like the killer whale, feed on mammals, such as pinnipeds. Males typically mate with multiple females every year, but females only mate every two to three years, making them polygynous. Calves are typically born in the spring and summer months and females bear the responsibility for raising them, but more sociable species rely on the family group to care for calves. Many species, mainly dolphins, are highly sociable, with some pods reaching over a thousand individuals. Once hunted for their products, cetaceans are now protected by international law. Some species are attributed with high levels of intelligence. At the 2012 meeting of the American Association for the Advancement of Science, support was reiterated for a cetacean bill of rights, listing cetaceans as non-human persons. Besides whaling and drive hunting, they also face threats from bycatch and marine pollution. The Baiji, for example, is considered functionally extinct by the IUCN, with the last sighting in 2004, due to heavy pollution to the Yangtze river. Whales occasionally feature in literature and film, as in the great white whale of Herman Melville's ''Moby Dick''. Small odontocetes, mainly dolphins, are kept in captivity and trained to perform tricks, but breeding success has been poor. Whale watching has become a form of tourism around the world. ==Taxonomy== * Infraorder Cetacea * * Parvorder Odontoceti: toothed whales * * * Superfamily Delphinoidea: dolphins and relatives * * * * Family Delphinidae: oceanic dolphins * * * * * Subfamily Delphininae * * * * * * Genus ''Delphinus'' * * * * * * * Short-beaked common dolphin, ''Delphinus delphis'' * * * * * * * Long-beaked common dolphin, ''Delphinus capensis'' * * * * * * * (Arabian common dolphin, ''Delphinus tropicalis'') * * * * * * Genus ''Lagenodelphis'' * * * * * * * Fraser's dolphin, ''Lagenodelphis hosei'' * * * * * * Genus ''Sousa'' * * * * * * * Atlantic humpback dolphin, ''Sousa teuszi'' * * * * * * * Indian humpback dolphin, ''Sousa plumbea'' * * * * * * * Chinese white dolphin, ''Sousa chinensis'' * * * * * * Genus ''Stenella'' (syn. Clymenia, Micropia, Fretidelphis, Prodelphinus) * * * * * * * Pantropical spotted dolphin, ''Stenella attenuata'' * * * * * * * Atlantic spotted dolphin, ''Stenella frontalis'' * * * * * * * Spinner dolphin, ''Stenella longirostris'' * * * * * * * Clymene dolphin, ''Stenella clymene'' * * * * * * * Striped dolphin, ''Stenella coeruleoalba'' * * * * * * Genus ''Tursiops'' * * * * * * * Bottlenose dolphin, ''Tursiops truncatus'' * * * * * * * Indian Ocean bottlenose dolphin, ''Tursiops aduncus'' * * * * * * * Burrunan dolphin, ''Tursiops australis'' * * * * * Subfamily Lissodelphininae * * * * * * Genus ''Cephalorhynchus'' (syn. ''Eutropia'') * * * * * * * Commerson's dolphin, ''Cephalorhynchus commersonii'' * * * * * * * Chilean dolphin, ''Cephalorhynchus eutropia'' * * * * * * * Heaviside's dolphin, ''Cephalorhynchus heavisidii'' * * * * * * * Hector's dolphin, ''Cephalorhynchus hectori'' * * * * * * Genus ''Lissodelphis'' (syn. ''Tursio, Leucorhamphus'') * * * * * * * Northern right whale dolphin, ''Lissodelphis borealis'' * * * * * * * Southern right whale dolphin, ''Lissodelphis peronii'' * * * * * Subfamily Orcininae * * * * * * Genus ''Feresa'' * * * * * * * Pygmy killer whale, ''Feresa attenuata'' * * * * * * Genus ''Globicephala'' (syn. ''Sphaerocephalus, Globiceps, Globicephalus'') * * * * * * * Long-finned pilot whale, ''Globicephala melas'' * * * * * * * Short-finned pilot whale, ''Globicephala macrorhyncus'' * * * * * * Genus ''Grampus'' (syn. ''Grampidelphis, Grayius'') * * * * * * * Risso's dolphin, ''Grampus griseus'' * * * * * * Genus ''Orcaella'' * * * * * * * Irrawaddy dolphin, ''Orcaella brevirostris'' * * * * * * * Australian snubfin dolphin, ''Orcaella heinsohni'' * * * * * * Genus ''Orcinus'' (syn. ''Orca, Ophysia, Gladiator'') * * * * * * * Killer whale (orca), ''Orcinus orca'' * * * * * * Genus ''Peponocephala'' * * * * * * * Melon-headed whale, ''Peponocephala electra'' * * * * * * Genus †''Platalearostrum'' (blunt-snouted dolphin) * * * * * * *†Hoekman's blunt-snouted dolphin, ''Platalearostrum hoekmani'' * * * * * * Genus ''Pseudorca'' (syn. ''Neorca'') * * * * * * * False killer whale, ''Pseudorca crassidens'' * * * * * Subfamily Stenoninae * * * * * * Genus ''Sotalia'' (syn. ''Tucuxa'') * * * * * * * Tucuxi, ''Sotalia fluviatilis'' * * * * * * * Costero, ''Sotalia guianensis'' * * * * * * Genus ''Steno'' (syn. ''Glyphidelphis, Stenopontistes'') * * * * * * * Rough-toothed dolphin, ''Steno bredanensis'' * * * * * Subfamily incertae sedis * * * * * * Genus ''Lagenorhynchus'' * * * * * * * White-beaked dolphin, ''Lagenorhynchus albirostris'' * * * * * * * Atlantic white-sided dolphin, ''Lagenorhynchus acutus'' * * * * * * * Pacific white-sided dolphin, ''Lagenorhynchus obliquidens'' * * * * * * * Dusky Dolphin, ''Lagenorhynchus obscurus'' * * * * * * * Black-chinned dolphin, ''Lagenorhynchus australis'' * * * * * * * Hourglass dolphin, ''Lagenorhynchus cruciger'' * * * * Family Monodontidae * * * * * Subfamily Delphinapterinae * * * * * * Genus ''Delphinapterus'' * * * * * * * Beluga whale, ''Delphinapterus leucas'' * * * * * Subfamily Monodontinae * * * * * * Genus ''Monodon'' * * * * * * * Narwhal, ''Monodon monoceros'' * * * * Family Phocoenidae: porpoises * * * * * Subfamily Phocoeninae * * * * * * Genus ''Neophocaena'' (syn. ''Meomeris'') * * * * * * * Finless porpoise, ''Neophocaena phocaenoides'' * * * * * * Genus ''Phocoena'' (syn. ''Australophocaena, Acanthodelphis'') * * * * * * * Harbour porpoise, ''Phocoena phocaena'' * * * * * * * Vaquita, ''Phocoena sinus'' * * * * * * * Spectacled porpoise, ''Phocoena dioptrica'' * * * * * * * Burmeister's porpoise, ''Phocoena spinipinnis'' * * * * * Subfamily Phocoenoidinae * * * * * * Genus ''Phocoenoides'' * * * * * * * Dall's porpoise, ''Phocoenoides dalli'' * * * Superfamily Inioidea, river dolphins * * * * Family Iniidae * * * * * Genus ''Inia'' * * * * * * Bolivian river dolphin, ''Inia boliviensis'' * * * * * * Amazon river dolphin, ''Inia geoffrensis'' * * * * * * Araguaian river dolphin, ''Inia araguaiaensis'' * * * * Family Pontoporiidae * * * * * Genus ''Pontoporia'' * * * * * * La Plata dolphin, ''Pontoporia blainvillei'' * * * Superfamily Platanistoidea, river dolphins * * * * Family Platanistidae * * * * * Genus ''Platanista'' * * * * * * Ganges and Indus River dolphin, ''Platanista gangetica'' * * * * Family †Squalodontidae * * * * * Genus †''Eosqualodon'' * * * * * Genus †''Macrophoca'' * * * * * Genus †''Neosqualodon'' * * * * * Genus †''Phoberodon'' * * * * * Genus †''Phocodon'' * * * * * Genus †''Smilocamptus'' * * * * * Genus †''Squalodon'' (jr. synonyms ''Arionius'', ''Crenidelphinus'', ''Kelloggia'', ''Rhizoprion'') * * * * * Genus †''Tangaroasaurus'' * * * Superfamily Lipotoidea, river dolphins (potentially extinct) * * * * Family Lipotidae * * * * * Genus ''Lipotes'' * * * * * * Chinese river dolphin, ''Lipotes vexillifer'' * * * Superfamily Physeteroidea, sperm whales * * * * Family Kogiidae * * * * * Genus ''Kogia'' * * * * * * Dwarf sperm whale, ''Kogia sima'' * * * * * * Pygmy sperm whale, ''Kogia breviceps'' * * * * Family Physeteridae: sperm whale family * * * * * Genus ''Physeter'' * * * * * * Sperm whale, ''Physeter macrocephalus'' * * *Superfamily Ziphioidea, beaked whales * * * * Family Ziphidae, beaked whales * * * * * Subfamily Berardiinae * * * * * * Genus ''Berardius'', giant beaked whales * * * * * * * Arnoux's beaked whale, ''Berardius arnuxii'' * * * * * * * Baird's beaked whale (North Pacific bottlenose whale), ''Berardius bairdii'' * * * * * Subfamily Hyperoodontinae * * * * * * Genus ''Hyperoodon'' * * * * * * * Northern bottlenose whale, ''Hyperoodon ampullatus'' * * * * * * * Southern bottlenose whale, ''Hyperoodon planifrons'' * * * * * * Genus ''Indopacetus'' * * * * * * * Tropical bottlenose whale (Longman's beaked whale), ''Indopacetus pacificus'' * * * * * * Genus ''Mesoplodon'', mesoplodont whales * * * * * * * Hector's beaked whale, ''Mesoplodon hectori'' * * * * * * * True's beaked whale, ''Mesoplodon mirus'' * * * * * * * Gervais' beaked whale, ''Mesoplodon europaeus'' * * * * * * * Sowerby's beaked whale, ''Mesoplodon bidens'' * * * * * * * Gray's beaked whale, ''Mesoplodon grayi'' * * * * * * * Pygmy beaked whale, ''Mesoplodon peruvianus'' * * * * * * * Andrews' beaked whale, ''Mesoplodon bowdoini'' * * * * * * * Bahamonde's beaked whale, ''Mesoplodon bahamondi'' * * * * * * * Hubbs' beaked whale, ''Mesoplodon carlhubbsi'' * * * * * * * Ginkgo-toothed beaked whale, ''Mesoplodon ginkgodens'' * * * * * * * Stejneger's beaked whale, ''Mesoplodon stejnegeri'' * * * * * * * Strap-toothed whale, ''Mesoplodon layardii'' * * * * * * * Blainville's beaked whale, ''Mesoplodon densirostris'' * * * * * * * Perrin's beaked whale, ''Mesoplodon perrini'' * * * * * * * Deraniyagala's beaked whale, ''Mesoplodon hotaula'' * * * * * Subfamily Ziphiinae * * * * * * Genus ''Tasmacetus'' * * * * * * * Shepherd's beaked whale (Shepherd's beaked whale), ''Tasmacetus shepherdi'' * * * * * * Genus ''Ziphius'' * * * * * * * Cuvier's beaked whale, ''Ziphius cavirostris'' 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「Toothed whale」の詳細全文を読む スポンサード リンク
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