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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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747 news items

Telegraph.co.uk

Telegraph.co.uk
Thu, 16 Oct 2014 13:48:45 -0700

Britain 'not doing enough to protect porpoise'. European Commission asks United Kingdom to designate protected areas for harbour porpoise. Harbour Porpoise (Phocoena phocoena) surfacing near the north end of the Isle of Coll, Agyll and Bute, Scotland ...

Tampabay.com

Tampabay.com
Fri, 17 Oct 2014 04:55:20 -0700

CLEARWATER — Seeking to harness the fame of its dolphins, Winter and Hope, for a worthy cause, the Clearwater Marine Aquarium is launching a campaign to save a near-extinct species of porpoise.

Folkestone Herald

Folkestone Herald
Tue, 14 Oct 2014 04:37:30 -0700

Dead porpoise found at the Warren. By AntonyThrower | Posted: October 14, 2014. Porpoise2. Comments (0). A DEAD porpoise has been found washed up on the beach at the Warren. The mammal was found on Sunday, October 12, and footage of the ...

Southland Times

Southland Times
Wed, 17 Sep 2014 21:09:08 -0700

Otago researchers say the quick reporting of a rare spectacled porpoise stranding on a Dunedin beach has given them an opportunity to research the little known creature. The 2.15m long spectacled porpoise, so-called because of markings around its eyes ...

Center for Biological Diversity (press release)

Center for Biological Diversity (press release)
Mon, 29 Sep 2014 08:22:30 -0700

The vaquita is the world's smallest porpoise and exists only in Mexico's Gulf of California. It has suffered a dramatic and alarming decline, dropping from 200 animals in 2012 to just 97 in 2014. Without help, scientists predict vaquitas could be ...
 
The Guardian
Fri, 17 Oct 2014 08:14:52 -0700

“Despite a large number of harbour porpoise in its waters, the UK has so far proposed only one small site in Northern Ireland [as a protected area], exposing some of the identified sites to the risk of offshore wind farm development,” a statement says.
 
PortageLife
Fri, 03 Oct 2014 08:45:00 -0700

Portage Porpoise Swim Club is now registering for Learn to Swim and Pre-Team Lessons as well as accepting new swimmers for the swim team. Anyone interested can come to the Portage High School Pool Door "O" Monday-Thursday 5p-8p or email Coach ...
 
Tampa Bay Newspapers
Mon, 22 Sep 2014 17:11:15 -0700

SEMINOLE - Bacchus Bike Fest is Saturday and Sunday, Sept. 27-28, at Screwie Louie's Porpoise Pub, 8701 Seminole Blvd. in Seminole. Events get underway Saturday, 10 a.m., with the start of a poker run. Gates open at 11 a.m. on Sunday. General ...
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