User:Chris huh/Cetaceans

The order Cetacea includes the whales, dolphins and porpoises and comprise the mammals most fully adapted to aquatic life. It contains 81 known species organized in two suborders: Mysticeti (baleen whales) and Odontoceti (toothed whales, which includes dolphins and porpoises). The order contains several record breaking species, with the Blue Whale being the largest animal ever, and the Orca being the most widely distributed animal.

Cetaceans evolved from land mammals that adapted to marine life about 50 million years ago. Over a period of a few millions of years during the Eocene, the cetaceans returned to the sea. Their body is fusiform (spindle-shaped), the forelimbs are modified into flippers, the tiny hindlimbs are vestigial and the tail has horizontal flukes. Cetaceans are nearly hairless, and are insulated by a thick layer of blubber.

Cetaceans inhabit all of the world's oceans, as well as some freshwater lakes and rivers in South America, North America, and Asia. Some species, like the Orca, or Killer Whale, can be found across the globe.

Cetology is the branch of marine science associated with the study of cetaceans.

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• ...whales and dolphins don’t sleep in the way humans do. Although we don’t know how they sleep, some scientists believe they sleep with half the brain asleep and half the brain awake, keeping them aware of danger.
• ...there are probably types of cetaceans that are as yet unknown. For example, the Longman's beaked whale is only known from skulls washed ashore in Somalia and Australia. It has never been seen alive!
• ...all whales and dolphins have the remains of the pelvis, but it is reduced to two small bones at the rear of the animal.
• ...the ‘strapped-toothed whale’ whale is so called because in mature males there are only two teeth in the bottom jaw and these completely ‘strap’ the upper jaw, preventing it from opening more than a few centimetres. How these animals eat is unknown, but it may be that they stun their prey with high intensity sound.
• ...some cetaceans can dive to depths of more than a kilometre and stay there for more than an hour.

The Dusky Dolphin (Lagenorhynchus obscurus) is a highly gregarious and acrobatic dolphin found in coastal waters in the Southern Hemisphere. It was first identified by John Gray in 1828. It is very closely genetically related to the Pacific White-sided Dolphin, although current scientific consenus is that they are distinct species.

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The content you are reading was created by Wikipedia. See the WikiProject Cetaceans for more.

Related WikiProjects include:

• Tree of Life
• Biology
• Science
• Birds
• Mammals
• Marine Life
• Sharks

See also Wikispecies, a Wikimedia project dedicated to the classification of species.