Porpoise
From Bioboy.org
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The 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. 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. Probably best known is the Harbour Porpoise, which can be found across the Northern Hemisphere.
[edit] Taxonomy and evolutionPorpoises, along with whales and dolphins, are descendants of land-living mammals and are related to hoofed animals. Evolutionary philosophy teaches they entered the water roughly 50 million years ago.
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. [edit] In popular cultureIn the 1966 Batman film, Batman and Robin are rescued by a "Noble Porpoise" who intercepted a torpedo that was headed in their direction. In the BBC comedy series, Blackadder The Third, the Prince Regent, played by Hugh Laurie, confuses the title of the story The Prince And The Pauper with The Prince And The Porpoise. [edit] See also[edit] References[edit] External links
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