AskDefine | Define porpoise

Dictionary Definition

porpoise n : any of several small gregarious cetacean mammals having a blunt snout and many teeth

User Contributed Dictionary

English

Pronunciation

Noun

  1. A small cetacean of the family Phocoenidae, related to whales and dolphins.
  2. In the context of "North America|imprecisely": Any small dolphin.

Translations

cetacean
imprecisely, any small dolphin

Extensive Definition

Porpoises are small cetaceans of the family Phocoenidae; they are related to whales and dolphins. They are distinct from dolphins, although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen. The most obvious visible difference between the two groups is that porpoises have flattened, spade-shaped teeth distinct from the conical teeth of dolphins, and their shorter beaks.
The name derives from French pourpois, originally from Medieval Latin porcopiscus (porcus pig + piscus fish).
Porpoises, divided into six species, live in all oceans, mostly near the shore. Freshwater populations of the Finless Porpoise also exist. Probably the best known species is the Harbour Porpoise, which can be found across the Northern Hemisphere. Like all toothed whales, porpoises are predators, using sounds to locate prey and to coordinate with others. They hunt fish, squid, and crustaceans.
Porpoises apparently diverged from dolphins about 15 million years ago in the northern Pacific, then spread across the globe much later.

Taxonomy and evolution

Porpoises, along with whales and dolphins, are descendants of land-living ungulates (hoofed animals) that first entered the oceans around 50 million years ago. During the Miocene (23 to 5 MYA), mammals were fairly modern. The cetaceans diversified, and fossil evidence suggests that porpoises diverged from dolphins and other cetaceans around 15 MYA. The oldest fossils are known from the shallow seas around the north Pacific, with animals spreading to the European coasts and southern hemisphere only much later, during the Pliocene.
Recently-discovered hybrids between male Harbour porpoises and female Dall's Porpoises indicate that the two species may actually be members of the same genus.
These animals are the smallest cetaceans, reaching body lengths up to 2.5 metres (8 ft); the smallest species is the Vaquita, reaching up to 1.5 m (5 ft). In terms of weight the lightest is the Finless Porpoise at 30-45 kilograms (65-100 lb) and the heaviest is Dall's Porpoise at 130-200 kg (280-440 lb). Because of their small size, porpoises lose body heat to the water more rapidly than other cetaceans. Their stout shape, which minimizes surface area, may be an adaptation to reduce heat loss. Thick blubber also insulates them from the cold. The small size of porpoises requires them to eat frequently, rather than depending on fat reserves.
In some countries, porpoises are hunted for food or bait meat.
Porpoises are rarely held in captivity in zoos or oceanaria, as they are generally not as capable of adapting to tank life nor as easily trained as dolphins.

See also

porpoise in Danish: Marsvin-familien
porpoise in German: Schweinswale
porpoise in Estonian: Pringellased
porpoise in Spanish: Marsopa
porpoise in Esperanto: Porkocetoj
porpoise in Persian: گرازماهی
porpoise in French: Phocoenidae
porpoise in Scottish Gaelic: Peallag
porpoise in Korean: 쇠돌고래과
porpoise in Croatian: Pliskavice
porpoise in Ido: Marsuino
porpoise in Italian: Phocoenidae
porpoise in Hebrew: פוקניים
porpoise in Lithuanian: Jūrų kiaulės
porpoise in Dutch: Bruinvissen
porpoise in Japanese: ネズミイルカ科
porpoise in Norwegian: Niser
porpoise in Polish: Morświnowate
porpoise in Portuguese: Phocoenidae
porpoise in Russian: Морские свиньи
porpoise in Simple English: Porpoise
porpoise in Finnish: Pyöriäiset
porpoise in Swedish: Tumlare
porpoise in Chinese: 鼠海豚科
porpoise in Chinese: bangla

Synonyms, Antonyms and Related Words

Loch Ness monster, alevin, benthon, benthos, cetacean, dolphin, fingerling, fish, fry, game fish, grilse, kipper, man-eater, man-eating shark, marine animal, minnow, minny, nekton, panfish, plankton, salmon, sea monster, sea pig, sea serpent, sea snake, shark, smolt, sponge, tropical fish, whale
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