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For other uses, see Porpoise (disambiguation).
Porpoises
Temporal range: 15.970–0Ma
Miocene to Recent
Harbor.Porpoise.4.jpg
Phocoena phocoena, harbour porpoise near Denmark
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Suborder: Odontoceti
Superfamily: Delphinoidea
Family: Phocoenidae
Gray, 1825
Genera

See text

Porpoises (/ˈpɔrpəs/; also called mereswine) 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 shorter beaks and flattened, spade-shaped teeth distinct from the conical teeth of dolphins.

The name derives from French pourpois, possibly from Medieval Latin porcopiscis (porcus pig + piscis fish; cf. classical porcus marīnus ("sea hog").[1]

Porpoises, divided into six species, live in all oceans, and 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 (echolocation in sonar form) to locate prey and to coordinate with others. They hunt fish, squid, and crustaceans.

Taxonomy and evolution[edit]

Porpoises, along with whales and dolphins, are descendants of land-living ungulates (hoofed animals) that first entered the oceans around 50 million years ago (Mya). During the Miocene (23 to 5 Mya), mammals were fairly modern. The cetaceans diversified, and fossil evidence suggests porpoises and dolphins diverged from their last common ancestor 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.[2]

Suborder Odontoceti toothed whales

Recently discovered hybrids between male harbour porpoises and female Dall's porpoises indicate the two species may actually be members of the same genus.[6]

Physical characteristics[edit]

A harbour porpoise at an aquarium.

Porpoises tend to be smaller but stouter than dolphins. They have small, rounded heads and blunt jaws instead of beaks. While dolphins have a round, bulbous "melon", porpoises do not. Their teeth are spade-shaped, whereas dolphins have conical teeth. In addition, a porpoise's dorsal fin is generally triangular, rather than curved like that of many dolphins and large whales. Some species have small bumps, known as tubercles, on the leading edge of the dorsal fin. The function of these bumps is unknown.[6]

These animals are the smallest cetaceans, reaching body lengths up to 2.5 metres (8.2 ft); the smallest species is the vaquita, reaching up to 1.5 metres (4.9 ft). In terms of weight, the lightest is the finless porpoise at 30 to 45 kilograms (66 to 99 lb), and the heaviest is Dall's porpoise at 130 to 200 kilograms (290 to 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.[6]

Life history[edit]

Porpoises bear young more quickly than dolphins. Female Dall's and harbour porpoises often become pregnant with a single calf each year, and pregnancy lasts for about 11 months. Porpoises have been known to live 8–10 years, although some have lived to be 20.[6]

Behavior[edit]

"Rooster tail" spray around swimming Dall's porpoises

Porpoises prey on fish, squid, and crustaceans. Although they are capable of dives up to 200 m, they generally hunt in shallow coastal waters. They are found most commonly in small groups of fewer than ten individuals, referred to as pods. Rarely, some species form brief aggregations of several hundred animals. Like all toothed whales, they are capable of echolocation for finding prey and group coordination. Porpoises are fast swimmers—Dall's porpoise is said to be one of the fastest cetaceans, with a speed of 55 km/h (34 mph). Porpoises tend to be less acrobatic and more sexually aggressive than dolphins.[7]

Humans and porpoises[edit]

Accidental entanglement (bycatch) in fishing nets is the main threat to porpoises today.[8] One of the most endangered cetacean species is the vaquita, having a limited distribution in the Gulf of California, a highly industrialized area. In some countries, porpoises are hunted for food or bait meat.[citation needed]

Porpoises are rarely held in captivity in zoos or oceanaria, as they are generally not as capable of adapting to tank life or as easily trained as dolphins.[citation needed]

See also[edit]

References[edit]

  1. ^ http://dictionary.reference.com/browse/porpoise?o=102213
  2. ^ Gaskin, David E. (1984). Macdonald, D., ed. The Encyclopedia of Mammals. New York: Facts on File. pp. 196–199. ISBN 0-87196-871-1. 
  3. ^ Ichishima, H. & Kimura, M.. 2005. "Harborophocoena toyoshimai, a new early Pliocene porpoise (Cetacea, Phocoenidae) from Hokkaido, Japan". Journal of Vertebrate Paleontology 25(3):655–664
  4. ^ Ichishima, H. & Kimura, M.. 2000. "A new fossil porpoise (Cetacea; Delphinoidea; Phocoenidae) from the early Pliocene Horokaoshirarika Formation, Hokkaido, Japan". Journal of Vertebrate Paleontology 20(3):561–576
  5. ^ Lambert, O.. 2008. "A new porpoise (Cetacea, Odontoceti, Phocoenidae) from the Pliocene of the North Sea". Journal of Vertebrate Paleontology 28(3):863–872
  6. ^ a b c d Read, Andrew (1999). Porpoises. Stillwater, MN, USA: Voyageur Press. ISBN 0-89658-420-8. 
  7. ^ http://appreviews4u.com/2013/03/11/porpoises-the-ignored-species/
  8. ^ http://www.iucnredlist.org/details/17028/0

External links[edit]

Media related to Phocoenidae at Wikimedia Commons


Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Porpoise — Please support Wikipedia.
This page uses Creative Commons Licensed content from Wikipedia. A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia.
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9281 news items

 
Huffington Post
Fri, 14 Nov 2014 09:58:37 -0800

Headlines from multiple British news outlets late last week stated that a porpoise found dead in an English alleyway died from “too much sex.” If that sounds too ridiculous to be true, it's because it is. “I'm afraid the journalist in question was a ...

Daily Mail

Daily Mail
Wed, 05 Nov 2014 05:20:01 -0800

The animal is a male harbour porpoise, which usually travel round in small groups and are traditionally hard to spot as they rarely come out of the water. From a distance they look similar to dolphins and are often found in the North Pacific, North ...

Malaysia Chronicle

Metro
Sat, 08 Nov 2014 07:41:14 -0800

A randy porpoise was found dead in a housing estate alleyway, in Tarring, West Sussex, on Saturday – but that was only the beginning of the story. The elderly Lothario had apparently died from starvation and hypothermia after burning too much energy ...

Newser

Newser
Thu, 13 Nov 2014 00:00:25 -0800

(Newser) – A 5-foot-long, 110-pound elderly male porpoise—which likely washed up on Worthing beach south of London before being dumped more than a mile inland—appears to have devoted so much of its energy to mating that it ultimately died of ...

TheCelebrityCafe.com

TheCelebrityCafe.com
Sun, 16 Nov 2014 00:07:57 -0800

The 110-pound porpoise was found dead on Nov. 1, leaving locals in Pilgrims Walk, Worthing puzzled. The British Divers Marine Life Rescue told The Argus that the porpoise likely washed up on the beach and was taken inland by a person who dumped the ...
 
Headlines & Global News
Thu, 13 Nov 2014 19:56:56 -0800

"The male porpoise was in a pretty poor way," Rob Deaville, from the Cetacean Strandings Investigation Programme, who carried out the porpoise's autopsy, tells Argus. "This appears to be an elderly porpoise, which would have had to expend most of his ...

Folkestone Herald

Folkestone Herald
Tue, 18 Nov 2014 04:22:30 -0800

A PORPOISE washed up on Sandgate beach was “hit by a boat”, according to those who found it. This picture was submitted to the Herald by Christian Plummer, who found the animal near the shore on Sunday, November 16 at 8.45am. Mr Plummer said: “It ...

Hernando Today

Hernando Today
Tue, 28 Oct 2014 12:55:49 -0700

Clearwater Marine Aquarium has begun an international conservation effort aimed at saving the vaquita porpoise, a species on the verge of extinction. The campaign, entitled “Winter's Hope for the Vaquita,” will create awareness and a call to action to ...
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