Cetacean



         


Mysticeti
Odontoceti

</table> The order Cetacea includes whales, dolphins and porpoises. Cetus is Latin and is used in biological names to mean "whale"; its original meaning was more general, "large sea animal". It comes from Greek ketos, a 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 10 families, and about 80 species.
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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 () for further details. Differences reflect usage of common names and further discoveries since the publication of that work.

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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.

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See also

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