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For other uses, see Porpoise (disambiguation).
Porpoises
Temporal range: 15.970–0 Ma
Miocene to Recent
Phocoena phocoena.2.jpg
The harbor porpoise (Phocoena phocoena)
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 Phocoenidae family; they are small toothed whales very closely related to oceanic 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 Old French porpeis, for porc peis (Medieval Latin: porcus piscis), pig-fish.[1] The Modern French term marsouin is cognate to Old English mereswīn.

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]

Porpoise species[edit]

There are eight recognized species of porpoise.

Species of porpoise
Species Description Image
Harbor porpoise (Phocoena phocoena) The harbor porpoise is a solitary, small toothed porpoise that lives in cold water, that can be found in small pods of 2-5 individuals. Harbor porpoises have spade-shaped teeth, which makes them distinguishable from dolphins. They have a triangular dorsal fin, a dark gray back, and a white underbelly. Harbor porpoises give birth every year, with gestation lasting about 10 months. They feed on shoaling fish and squid in the cold waters of the North Pacific and the North Atlantic coastlines for their 24 year life span. They can weigh in at 61–77 kg, and can be 1.5–1.7 meters. [7]
Harbor porpoise
Vacquita/Gulf of California harbor porpoise (Phocoena sinus) The vacquita is a very elusive porpoise that inhabits, obviously, the Gulf of California, in small pods of 7–10 individuals. The vacquita was first described in 1958 by a series of skulls. They do not have robust bodies or beaks. Weighing in at 30–55 kg, and being 1.2–1.5 meters long, it is the smallest known cetacean. After a gestation period of 10–11 months, they usually give birth to one calf every other year, and have a lifespan of approximately 21 years. [8]
A pair of vaquitas swim together.
Dall's porpoise (Phocoenoides dalli) Dall's porpoise describes two very fast subspecies of porpoise that are capable of diving 500 meters to feed on shoaling fish, cephalopods, and occasionally crustaceans in the North Pacific Ocean in pods of up to 20 individuals. P.d. truei inhabits the Western Pacific Ocean, whereas P. dalli inhabits the Northern Pacific. When they surface they create a rooster tail that is unique ability, among porpoises. They give birth every year and live generally 15–20 years, but can live to be 22. They weigh in at 220 kg and are 2–2.4 meters long. [9]
Dall's porpoise
Burmeister's porpoise (Phocoena spinipinnus) Burmeister's porpoise is a porpoise with a uniquely positioned dorsal fin, with a triangular dorsal fin angled backwards and set back farther than any other cetacean. The approximate 500 individuals inhabit the coast of Patagonia and eat small fish, mollusks, and cephalopods and have been heavily hunted for thousands of years. Burmeister's porpoise has a jet black to dark gray coloring, which gives it its nickname "the black porpoise". Burmeister's porpoise maximum length on record is 200 cm and the maximum weight is 79kg. [10] [11]
Burmeister's porpoise size comparison
Spectacled porpoise (Phocoena dioptrica) The spectacled porpoise is a rarely seen species of porpoise with a blue/black back and a white underbelly with no transitional colors between the blue and white, and pitch black patch around the eye. As a result of their elusiveness, almost nothing is known about the life of this species. Generally, spectacled porpoises travel in groups of 2, or travel alone. Sightings of them take place along the east coast of Patagonia and the Falkland Islands. They are a small species of porpoise, just measuring 1.3–2.2 meters and weighing 60–115 kg. [12]
Illustration of a spectacled porpoise
Narrow ridged finless porpoise (Neophocaena asiaorientalis) The finless porpoise has two recognized subspecies: N. a. asiaorientalis which inhabits the Yangtze River, and N. a. sunameri which inhabits the coast of Taiwan to southern Japan. They have no fin, but instead have a ridge from their blowhole to their tail fluke. They have a blue/gray color and about half of them have pink eyes. They are officially protected in China, but are declining due to habitat destruction. They are 1.9 meters in length, weigh 30–45 kg, and are though to live for between 10 and 20 years. [13]
Two narrow ridged finless porpoises
Indo-Pacific finless porpoise (Neophocaena phocaenoides) Originally classified in the same species as the narrow ridged finless porpoise, the two were split into two different species when it was proven that they could not breed together. The Indo-Pacific finless porpoise inhabits the coastline between the Persian Gulf and Taiwan. They have no fin, but instead have a ridge from their blowhole to their tail fluke. They have a blue/gray color and about half of them have pink eyes. They are officially protected in China, but are declining due to habitat destruction, and Pakistan has fisheries specifically targeting finless porpoises. They are 1.9 meters in length, weigh 30–45 kg, and are though to live for between 10 and 20 years. [14]
Indo-Pacific finless porpoise

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.

Humans and porpoises[edit]

Accidental entanglement (bycatch) in fishing nets is the main threat to porpoises today.[15] 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]

Traditionally porpoises under English law were a royal fish which belonged to the Crown.[16]

See also[edit]

References[edit]

  1. ^ Ernest Weekley The Romance of Words, Murray, London 1912
  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. doi:10.1671/0272-4634(2000)020[0561:ANFPCD]2.0.CO;2. JSTOR 4524127.  edit
  5. ^ Lambert, O. (2008). "A new porpoise (Cetacea, Odontoceti, Phocoenidae) from the Pliocene of the North Sea". Journal of Vertebrate Paleontology 28 (3): 863. doi:10.1671/0272-4634(2008)28[863:ANPCOP]2.0.CO;2.  edit
  6. ^ a b c d Read, Andrew (1999). Porpoises. Stillwater, MN, USA: Voyageur Press. ISBN 0-89658-420-8. 
  7. ^ NOAA Fisheries. "Harbor Porpoise". NOAA Fisheries. 
  8. ^ NOAA Fisheries. "Vacquita". NOAA Fisheries. 
  9. ^ NOAA Fisheries. "Dall's Porpoise". NOAA Fisheries. 
  10. ^ CMS. "Burmeister's Porpoise (stats)". CMS. 
  11. ^ MarineBio. "Burmeister's Porpoise". MarineBio. 
  12. ^ MarineBio. "Spectacled Porpoise". MarineBio. 
  13. ^ MarineBio. "Narrow Ridged Finless Porpoise". MarineBio. 
  14. ^ WDC. "Indo-Pacific Finless Porpoise". WDC. 
  15. ^ Rojas-Bracho, L., Reeves, R.R., Jaramillo-Legorreta, A. & Taylor, B.L. (2008). Phocoena sinus. The IUCN Red List of Threatened Species. Version 2014.3.
  16. ^ Hale De Jure Maris c.7

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.

8340 news items

KIRO Seattle

KIRO Seattle
Sat, 25 Jul 2015 15:32:44 -0700

Employees with Semiahmoo Resort in Whatcom County raced to the beach area where the porpoise was, and moved the creature swiftly back into the water. They contacted the Whatcom Marine Mammal Stranding Network for instructions on how to keep the ...

CTV News

CTV News
Fri, 24 Jul 2015 13:37:30 -0700

An unusual guest stopped by Washington's Semiahmoo Resort Thursday night when a juvenile harbour porpoise became stranded on a nearby beach. Guests noticed that a struggling porpoise had strayed too close to the shore, and notified staff. Semiahmoo ...

UPI.com

UPI.com
Wed, 15 Jul 2015 07:41:06 -0700

CRICCIETH, Wales, July 15 (UPI) -- A Welsh man shooting video with his dog during a walk on the beach recorded the moment his pet led him to a beached baby porpoise he was able to rescue. Rich Wilcock, whose video was shared on YouTube, was ...

Torquay Herald Express

Torquay Herald Express
Wed, 29 Jul 2015 05:00:00 -0700

PORPOISE and whale sightings off South Devon form part of the largest ever survey of its kind around the UK coast. This week, the UK conservation research charity, Sea Watch Foundation, is calling for thousands of observers around the British Isles to ...

TakePart

TakePart
Tue, 21 Jul 2015 17:01:53 -0700

In April, it looked like the world's smallest and most endangered porpoise was getting the help it needed from the Mexican government to avoid extinction. A ban on gill-net fishing—the leading cause of death for the vaquita—was put in place in the ...
 
Jakarta Post
Fri, 24 Jul 2015 20:33:45 -0700

In Indonesia, the porpoise can only be found in the Mahakam River's Muara Kaman estuary and at times in the waters of the Kutai Kartanegara regency capital of Tenggarong. In the 1980s, they could still be seen near the provincial capital of Samarinda.

abc7news.com

abc7news.com
Thu, 02 Jul 2015 17:16:03 -0700

Harbor porpoise spotted swimming in Napa River. Harbor porpoise spotted swimming in Napa River. A rare sight is attracting spectators in wine country -- a harbor porpoise has been spotted swimming in the Napa River! Embed. <iframe width="476" ...

U-T San Diego

U-T San Diego
Wed, 08 Jul 2015 17:38:03 -0700

Despite well-placed facial markings giving the appearance of a permanent smile, the outlook couldn't be sadder for the world's smallest porpoise. Down to 50 individuals or less, according to the latest science, the disappearance of the vaquita ...
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