Although the International Whaling Commission has agreed on putting a halt to commercial whaling, whale hunting is still going on, either under IWC quotas to assist the subsistence of Arctic native people or in the name of scientific research, although a large spectrum of non-lethal methods are now available to study marine mammals in the wild. Despite their highly modified bodies and carnivorous lifestyle, genetic and fossil evidence places cetaceans as nested within even-toed ungulates, most closely related to hippopotamus within the clade Whippomorpha.Ĭetaceans have been extensively hunted for their meat, blubber and oil by commercial operations. There are approximately 89 living species split into two parvorders: Odontoceti or toothed whales (containing porpoises, dolphins, other predatory whales like the beluga and the sperm whale, and the poorly understood beaked whales) and the filter feeding Mysticeti or baleen whales (which includes species like the blue whale, the humpback whale and the bowhead whale). Having a cosmopolitan distribution, they can be found in some rivers and all of Earth's oceans, and many species inhabit vast ranges where they migrate with the changing of the seasons.Ĭetaceans are famous for their high intelligence and complex social behaviour as well as for the enormous size of some of the group's members, such as the blue whale which reaches a maximum confirmed length of 29.9 meters (98 feet) and a weight of 173 tonnes (190 short tons), making it the largest animal known ever to have existed. While the majority of cetaceans live in marine environments, a small number exclusively reside in brackish water or fresh water. They propel themselves through the water with powerful up-and-down movement of their tail which ends in a paddle-like fluke, using their flipper-shaped forelimbs to maneuver. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. Clockwise from top: sperm whale ( Physeter macrocephalus), Amazon river dolphin ( Inia geoffrensis), Blainville's beaked whale ( Mesoplodon densirostris), southern right whale ( Eubalaena australis), narwhal ( Monodon monoceros), humpback whale ( Megaptera novaeangliae), orca ( Orcinus orca), gray whale ( Eschrichtius robustus) and harbor porpoise ( Phocoena phocoena).Ĭetaceans ( / s ɪ ˈ t eɪ ʃ ə n z/ from Latin cetus ' whale', from Ancient Greek κῆτος ( kêtos) ' huge fish, sea monster') are an infraorder of aquatic mammals that includes whales, dolphins, and porpoises.
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