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Dall's Porpoise (Phocoenoides dalli)

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Dall's Porpoise / GregTheBusker, Flickr

Dall's Porpoise

GregTheBusker, Flickr

The Dall's porpoise, or Dall porpoise, got its name from W.H. Dall, a naturalist who was the first to collect a specimen of the Dall's porpoise in 1873. These are one of the fastest cetacean species, and are capable of speeds over 30 miles per hour. They swim so quickly that they create a "rooster tail" of water as they are swimming.

Description:

Dall's porpoises can grow to 7-8 feet in length and 480 pounds in weight. Males are larger and more robust than females. Like other porpoises, Dall's porpoises have a stocky body, a blunt snout, spade-shaped teeth, and small flippers. They have a small, triangular dorsal fin that may angle forward. Unlike other porpoises, they do not have tubercles (bumps) on the front edge of their dorsal fin.

Dall's porpoises have a dark gray to black body with white patches, and white pigmentation on the dorsal fin and tail.

These porpoises are usually found in groups of 2-20 porpoises, but have been seen in groups up to the thousands. They may also be seen with baleen whales, short-finned pilot whales, and Pacific white-sided dolphins.

Dall's porpoises have 19-24 teeth in each side of their upper and lower jaw. The teeth are separated by hard growths called "gum teeth," the function of which is not known, but they may aid in grasping slippery prey.

Classification:

  • Kingdom: Animalia
  • Phylum: Chordata
  • Subphylum: Vertebrata
  • Superclass: Gnathostomata, Tetrapoda
  • Class: Mammalia
  • Subclass: Theria
  • Order: Cetartiodactyla
  • Suborder: Cetancodonta
  • Suborder: Odontoceti
  • Infraorder: Cetacea
  • Superfamily: Odontoceti
  • Family: Phocoenidae
  • Genus: Phocoenoides
  • Species: dalli

The Society for Marine Mammalogy lists 2 subspecies of Dall's porpoise:

  • Phocoenoides dalli dalli, in the North Pacific Ocean
  • Phocoenoides dalli truei, in the Western Pacific Ocean

Habitat and Distribution:

Dall's porpoises live in warm temperate to subarctic, deep waters of the Pacific Ocean, from the Bering Sea to Baja California Mexico. They tend to live in waters colder than 64 degrees (18 degrees C), and are usually offshore, but may also live in fjords and channels.

Feeding:

The Dall's porpoise eats fish, cephalopods and crustaceans. Like other toothed whales, they use echolocation to find their prey.

Reproduction:

Dall's porpoises are sexually mature at 7 (females) or 8 (males) years of age. After mating, the female has a 10-12 month gestation period, then gives birth to a calf that is about 3.5 feet long and weighs 55 pounds. The maximum lifespan of the Dall's porpoise is thought to be 20 years.

Conservation:

Harbor porpoises are listed as "of least concern" on the IUCN Red List. In the U.S., they are protected by the Marine Mammal Protection Act.

Threats to these porpoises include interaction with fishing gear, pollution, and harvesting, which occurs in Japan.

References and Further Information:

  • American Cetacean Society. Dall's Porpoise. Accessed October 30, 2012.
  • NOAA Fisheries: Office of Protected Resources. Dall's Porpoise (Phocoenoides dalli). Accessed October 30, 2012.
  • Perrin, W. 2012. Phocoenoides dalli (True, 1885). In: Perrin, W.F. (2012) World Cetacea Database. Accessed through: World Register of Marine Species at http://www.marinespecies.org/authority/aphia.php?p=taxdetails&id=254987 on 2012-10-30 Accessed October 30, 2012.
  • Read, A., "Porpoises, Overview". In Perrin, W.F., Wursig, B. and J.G.M. Thewissen, Eds. 2002. Encyclopedia of Marine Mammals. Academic Press.

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