porpoise

ネズミイルカ

関

Phocoena

　 　

WordNet

1. any of several small gregarious cetacean mammals having a blunt snout and many teeth
2. porpoises (同)genus Phocoena
3. the common porpoise of the northern Atlantic and Pacific (同)herring hog, Phocoena phocoena
4. a yellow fatty oil obtained from porpoises and used as a fine lubricant

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1. ネズミイルカ(北太平洋,北大西洋にすむ鼻先の丸い種類のイルカ)

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/06/05 19:06:45」(JST)

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For other uses, see Porpoise (disambiguation).

Porpoises Temporal range: 15.970–0Ma PreЄ Є O S D C P T J K Pg N Miocene to Recent
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").

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

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 (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.

Suborder Odontoceti toothed whales

• Infraorder Delphinida
  • Superfamily Delphinoidea
    • Family Phocoenidae - porpoises
      • Genus †Haborophocoena
        • H. toyoshimai
      • Genus Neophocaena
        • N. phocaeniodes - Finless porpoise
      • Genus †Numataphocoena
        • N. yamashitai
      • Genus Phocoena
        • P. phocoena - harbour porpoise
        • P. sinus - vaquita
        • P. dioptrica - spectacled porpoise
        • P. spinipinnis - Burmeister's porpoise
      • Genus Phocoenoides
        • P. dalli - Dall's porpoise
      • Genus †Septemriocetus
        • S. bosselaersii
      • Genus †Piscolithax
        • P. aenigmaticus
        • P. longirostris
        • P. boreios
        • P. tedfordi

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

Physical characteristics

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. Because porpoises have a spongy material within their loose, layered skin which beats rhythmically with the motion of the water to strongly reduce water drag, porpoises can swim faster than any other creature in the sea.

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.

Life history

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.

Behavior

"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.

Humans and porpoises

See also: Cetacean bycatch

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. 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 or as easily trained as dolphins.

See also

• List of cetaceans by population
• Unihemispheric slow-wave sleep

References

External links

Media related to Phocoenidae at Wikimedia Commons

• Whale Trackers - An online documentary series about whales, dolphins and porpoises.

English Journal

• An assessment of contaminant concentrations in toothed whale species of the NW Iberian Peninsula: part I. Persistent organic pollutants.

• Méndez-Fernandez P1, Webster L2, Chouvelon T3, Bustamante P3, Ferreira M4, González AF5, López A6, Moffat CF2, Pierce GJ7, Read FL5, Russell M2, Santos MB8, Spitz J9, Vingada JV10, Caurant F3.
• The Science of the total environment.Sci Total Environ.2014 Jun 15;484:196-205. doi: 10.1016/j.scitotenv.2014.02.045. Epub 2014 Apr 13.
• Concentrations and patterns of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in the blubber of the five most common toothed whales off the Northwest Iberian Peninsula (NWIP), specifically common dolphin, long-finned pilot whale, harbour porpoise, striped dolphin and bot
• PMID 24726511

• An assessment of contaminant concentrations in toothed whale species of the NW Iberian Peninsula: part II. Trace element concentrations.

• Méndez-Fernandez P1, Webster L2, Chouvelon T3, Bustamante P3, Ferreira M4, González AF5, López A6, Moffat CF2, Pierce GJ7, Read FL5, Russell M2, Santos MB8, Spitz J9, Vingada JV10, Caurant F3.
• The Science of the total environment.Sci Total Environ.2014 Jun 15;484:206-17. doi: 10.1016/j.scitotenv.2014.03.001. Epub 2014 Apr 1.
• Concentrations of Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, V and Zn were investigated in the liver and kidney of the five most common toothed whales off the Northwest Iberian Peninsula (NWIP), specifically common dolphin, long-finned pilot whale, harbour porpoise, striped dolphin and bottleno
• PMID 24702724

• Acoustic capture-recapture method for towed acoustic surveys of echolocating porpoises.

• Kimura S1, Akamatsu T2, Dong L3, Wang K3, Wang D3, Shibata Y4, Arai N5.
• The Journal of the Acoustical Society of America.J Acoust Soc Am.2014 Jun;135(6):3364.
• Passive acoustic monitoring for cetaceans mainly employ fixed-location methods or point transect samplings; an acoustic survey from a moving platform to conduct line transects is less common. In this study, acoustic capture-recapture by combining a double-observer method with line transect sampling
• PMID 24907799

Japanese Journal

• 瀬戸内海東部海域におけるスナメリ調査 (特集 日本のスナメリ研究最前線(1))

• 中村 清美
• 海洋と生物 36(1), 66-70, 2014-02
• NAID 40019997366

• ここまでわかった大阪湾のスナメリ (特集 日本のスナメリ研究最前線(1))

• 近藤 茂則,神田 育子,石田 義成 [他]
• 海洋と生物 36(1), 58-65, 2014-02
• NAID 40019997333

• 大阪湾におけるスナメリの調査活動について (特集 日本のスナメリ研究最前線(1))

• 西本 周平,石川 恵,地本 和史
• 海洋と生物 36(1), 50-57, 2014-02
• NAID 40019997308

Related Links

• Porpoise | Define Porpoise at Dictionary.com

1309, from O.Fr. porpais (12c.), lit. "pork fish," from porc "pork" (see pork) + peis "fish," from L. piscis "fish." The O.Fr. word is probably a loan-translation of a Gmc. word, cf. M.Du. mereswijn "porpoise" (cf. Mod.Fr. marsouin).

• porpoise - J:COM NET powered by ZAQ

you are th gest of this room! Thank you! porpoise（すなめり）：Finless porpoise ネズミイルカ科Neophocaena phocaenoides 背びれ、くちばしが無い小さなイルカ 全身銀灰色で体長1.5～1.9m Since 2001.1.1 http://members.home.ne ...

Related Pictures

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リンク元	「Phocoena」「ネズミイルカ」

「Phocoena」

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ネズミイルカ、ズミイルカ属

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porpoise

　

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英

porpoise、Phocoena

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ネズミイルカ属