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{{CompPsy}}
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i like eggs cool right
  
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{{Taxobox
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| name = Porpoises
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| fossil_range = {{Fossil range|Middle Miocene|Recent}}
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| image = Porpoise touching.jpg
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| image_width = 225px
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| image_caption = ''Phocoena phocoena'', [[Harbour Porpoise]] at the Fjord & Bæltcentret in Denmark
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| regnum = [[Animal]]ia
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| phylum = [[Chordata]]
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| classis = [[Mammalia]]
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| ordo = [[Cetacea]]
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| subordo = [[Odontoceti]]
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| familia = '''Phocoenidae'''
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| familia_authority = [[John Edward Gray|Gray]], 1825
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| subdivision_ranks = [[Genus|Genera]]
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| subdivision =
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''[[Neophocaena]]'' - Finless porpoise<br />
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''Phocoena'' - [[Harbour porpoise]] ''et al.''<br />
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''[[Phocoenoides]]'' - Dall's porpoise
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}}
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'''Porpoises''' are small [[cetacea]]ns of the [[family]] '''Phocoenidae'''; they are related to [[whale]]s and [[dolphin]]s. 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 shorter beaks.
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The name derives from French ''pourpois'', originally from Medieval Latin ''porcopiscus'' (''porcus'' pig + ''piscus'' fish).
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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.
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Porpoises apparently diverged from dolphins about 15 million years ago in the northern Pacific, then spread across the globe much later.
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== Taxonomy and evolution==
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{{See also|Evolution of cetaceans}}
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Porpoises, along with whales and dolphins, are descendants of land-living [[ungulate]]s (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]].<ref name=EoM>{{cite book |editor=Macdonald, D.|author= Gaskin, David E.|year=1984 |title= The Encyclopedia of Mammals|publisher= Facts on File|location=New York|pages= 196–199|isbn= 0-87196-871-1}}</ref>
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* '''Sub-order [[Odontoceti]]''': toothed whales
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**Family [[Phocoenidae]]: Porpoises
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***Genus ''[[Neophocaena]]''
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****[[Finless Porpoise]], ''Neophocaena phocaeniodes''
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***Genus ''[[Phocoena]]''
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****[[Harbour Porpoise]], ''Phocoena phocoena''
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****[[Vaquita]], ''Phocoena sinus''
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****[[Spectacled Porpoise]], ''Phocoena dioptrica''
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****[[Burmeister's Porpoise]], ''Phocoena spinipinnis''
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***Genus ''[[Phocoenoides]]''
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****[[Dall's Porpoise]], ''Phocoenoides dalli''</div>
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Recently-discovered [[Hybrid (biology)|hybrid]]s between male Harbour porpoises and female [[Dall's Porpoise]]s indicate that the two species may actually be members of the same [[genus]].<ref name=read/>
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== Physical characteristics ==
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[[Image:Marsvin (Phocoena phocoena) light.jpg|thumb|right|A [[Harbour Porpoise]] at an aquarium. In the wild, porpoises rarely jump out of the water.]]
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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 (whale)|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. <ref name=read>{{cite book| author=Read, Andrew |title= ''Porpoises''|year=1999|publisher=Voyageur Press |location=Stillwater, MN, USA|isbn=0-89658-420-8}}</ref>
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These animals are the smallest [[cetaceans]], reaching body lengths up to 2.5&nbsp;metres (8&nbsp;ft); the smallest species is the [[Vaquita]], reaching up to 1.5&nbsp;m (5&nbsp;ft). In terms of weight the lightest is the [[Finless Porpoise]] at 30-45&nbsp;[[kilogram]]s (65-100&nbsp;[[pound (mass)|lb]]) and the heaviest is [[Dall's Porpoise]] at 130-200&nbsp;kg (280-440&nbsp;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.<ref name=read/>
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==Life history==
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Porpoises are relatively [[R/K selection theory|r-selected]] compared with dolphins: that is, they rear 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 there are some that lived to be 20.<ref name=read/>
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== Behavior ==
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[[Image:Two Dalls Porpoises.JPG|thumb|right|250px|"Rooster tail" spray around swimming [[Dall's Porpoise]]s]]
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Porpoises are predators of fish, squid, and crustaceans. Although they are capable of dives up to 200&nbsp;m, they generally hunt in shallow coastal waters. They are found most commonly in small groups of fewer than ten individuals. Rarely, some species form brief aggregations of several hundred animals. Like all [[toothed whales]] they are capable of [[animal echolocation|echolocation]] for finding prey and group coordination. Porpoises are fast swimmers&mdash;[[Dall's porpoise]] is said to be one of the fastest cetaceans, with a speed of 55&nbsp;km/h (34&nbsp;mph). Porpoises tend to be less acrobatic and more wary than dolphins.
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== Human impact ==
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Accidental entanglement (bycatch) in fishing nets is the main threat to porpoises today. One of the most endangered cetacean species is the [[Vaquita]], having a limited distribution in the Gulf of California, a highly industrialized area.<ref>{{cite web| url=http://www.theporpoisepage.com/vaquita.php|title=The Porpoise Page - Information on Porpoises | accessdate=2006-11-03}}</ref>
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In some countries, porpoises are hunted for food or bait meat.
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Porpoises are rarely held in [[Animal captivity|captivity]] in [[zoo]]s or oceanaria, as they are generally not as capable of adapting to tank life nor as easily trained as dolphins.
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==See also==
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{{cetaceaportal}}
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*[[Dolphin]]
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*[[Whale]]
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== References ==
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{{reflist}}
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{{Cetacea|O.1}}
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[[bg:Морски свине]]
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[[ca:Marsopa]]
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[[da:Marsvin-familien]]
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[[de:Schweinswale]]
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[[et:Pringellased]]
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[[es:Phocoenidae]]
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[[eo:Porkocetoj]]
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[[fa:گرازماهی]]
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[[fr:Phocoenidae]]
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[[gd:Peallag]]
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[[ko:쇠돌고래과]]
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[[hr:Pliskavice]]
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[[io:Marsuino]]
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[[it:Phocoenidae]]
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[[he:פוקניים]]
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[[lt:Jūrų kiaulės]]
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[[nl:Bruinvissen]]
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[[ja:ネズミイルカ科]]
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[[no:Niser]]
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[[pl:Morświnowate]]
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[[pt:Phocoenidae]]
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[[ru:Морские свиньи]]
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[[simple:Porpoise]]
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[[fi:Pyöriäiset]]
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[[sv:Tumlare]]
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[[zh:鼠海豚科]]
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-->
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{{enWP|Porpoises}}
 
[[Category:Porpoises|*]]
  
[[Category:Porpoises|*]]
 
[[Category:Whales]]
  
[[Category:Whales]]

Latest revision as of 22:53, 1 June 2010

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?Porpoises
Fossil range: Template:Fossil range
Phocoena phocoena, Harbour Porpoise at the Fjord & Bæltcentret in Denmark
Phocoena phocoena, Harbour Porpoise at the Fjord & Bæltcentret in Denmark
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Suborder: Odontoceti
Family: Phocoenidae
Gray, 1825
Genera

Neophocaena - Finless porpoise
Phocoena - Harbour porpoise et al.
Phocoenoides - Dall's porpoise

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 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

See also: Evolution of cetaceans

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.[1]

  • Sub-order Odontoceti: toothed whales
    • Family Phocoenidae: Porpoises
      • Genus Neophocaena
        • Finless Porpoise, Neophocaena phocaeniodes
      • Genus Phocoena
        • Harbour Porpoise, Phocoena phocoena
        • Vaquita, Phocoena sinus
        • Spectacled Porpoise, Phocoena dioptrica
        • Burmeister's Porpoise, Phocoena spinipinnis
      • Genus Phocoenoides
        • Dall's Porpoise, Phocoenoides dalli

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.[2]

Physical characteristics

File:Marsvin (Phocoena phocoena) light.jpg

A Harbour Porpoise at an aquarium. In the wild, porpoises rarely jump out of the water.

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. [2]

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.[2]

Life history

Porpoises are relatively r-selected compared with dolphins: that is, they rear 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 there are some that lived to be 20.[2]

Behavior

File:Two Dalls Porpoises.JPG

"Rooster tail" spray around swimming Dall's Porpoises

Porpoises are predators of 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. 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 wary than dolphins.

Human impact

Accidental entanglement (bycatch) in fishing nets is the main threat to porpoises today. One of the most endangered cetacean species is the Vaquita, having a limited distribution in the Gulf of California, a highly industrialized area.[3]

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

.


References

  1. ↑ Gaskin, David E. (1984). Macdonald, D. The Encyclopedia of Mammals, 196–199, New York: Facts on File.
  2. ↑ 2.0 2.1 2.2 2.3 Read, Andrew (1999). 'Porpoises', Stillwater, MN, USA: Voyageur Press.
  3. ↑ The Porpoise Page - Information on Porpoises. URL accessed on 2006-11-03.



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