Cetacea
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Humpback Whale breeching
<tr><th bgcolor=pink>Scientific classification
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<tr><td>Kingdom:<td>Animalia
<tr><td>Phylum:<td>Chordata
<tr><td>Class:<td>Mammalia
<tr><td>Order:<td>Cetacea
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<tr><th bgcolor=pink>Suborders
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Mysticeti
Odontoceti
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The order Cetacea includes whales, dolphins and porpoises.
Cetus is Latin and is used in biological names to mean "whale"; its original meaning, "large sea animal," was more general, It comes from Greek ketos ("sea monster").
Cetaceans are the mammals most fully adapted to aquatic life. Their body is fusiform (spindle-shaped). The forelimbs are modified into flippers. The tiny hindlimbs are vestigial, they do not attach to the backbone and are hidden within the body. The tail has horizontal flukes.
Cetaceans are nearly hairless, and are insulated by a thick layer of blubber.
Cetacea contains ten families, and about 80 species.
Taxonomical listing
The specification shown here closely follows that of "Marine Mammals of the World. Systematics and Distribution", by Dale W. Rice (1998). Published by the Society of Marine Mammalogy as Special Publication No. 4, the tract has become the standard taxonomy reference in the field. See the Society's website (here (http://www.marinemammalogy.org/publications.htm)) for further details. Differences reflect usage of common names and further discoveries since the publication of that work.
- ORDER CETACEA
- Suborder Mysticeti: Baleen whales
- Suborder Odontoceti: toothed whales
- Superfamily Platanistoidea: River dolphins
- Family Monodontidae
- Family Phocoenidae: Porpoises
- Family Physeteridae: Sperm Whale family
- Family Kogiidae
- Family Ziphidae, Beaked whales
- Genus Ziphius
- Genus Berardius
- Genus Tasmacetus
- Subfamily Hyperoodontidae
- Genus Indopacetus
- Genus Hyperoodon
- Genus Mesoplodon, Mesoplodont Whale
- 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
- Andrew's Beaked Whale, Mesoplodon bowdoini
- Bahamonde's Beaked Whale, Mesoplodon bahamondi
- Hubb's Beaked Whale, Mesoplodon carlhubbsi
- Ginko-toothed Beaked Whale, Mesoplodon gingkgodens
- Stejneger's Beaked Whale, Mesoplodon stejnegeri
- Layard's Beaked Whale, Mesoplodon layardii
- Blainville's Beaked Whale, Mesoplodon densirostris
- Family Delphinidae: Dolphin
Evolution of cetaceans
The cetaceans are descendants of land-living mammals, most likely of the Artiodactyl order. They entered the water roughly 50 million years ago. See evolution of cetaceans for the details.
See also
External links
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