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Northern right whale dolphin
Size comparison against an average human
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Family: Delphinidae
Genus: Lissodelphis
Species: L. borealis
Peale, 1848[2]
Binomial name
Lissodelphis borealis
Range map

Northern right whale dolphin is a common name for Lissodelphis borealis, a small and slender species of mammal found in the Pacific Ocean. The northern right whale dolphin travels in groups of up to 2000, often with other cetaceans, in the deep oceans of the northern hemisphere. The dolphin is one of two species of right whale dolphin, the other being found in cooler oceans of the southern hemisphere.

The species has a streamlined body with a sloping forehead, are more slender than other delphinids, and lack any fin or ridge on their smoothly curving backs.[3][4] The beak is short and well defined, a straight mouthline, and an irregular white patch on chin. The flippers are small, curved, narrow and pointed, the body is mostly black while the underside is partly white or lighter in colour. The tail flukes are triangular and, like the flippers, pointed. Adults weigh between 60-100kg.[3] They have 74 to 108 thin and sharp teeth, not externally visible.[4] As young calves, these dolphins are greyish brown or sometimes cream. They stay like this for a year, before their body turns mainly black, with a clear white belly, and a white streak to their lower jaw.

Adults range in size from 2 metres in length, females are recorded as 2.3-2.6 m, males at 3.1 m, the sexes are otherwise similar in colour and appearance.[4][5] New-borns are around 90 centimetres. Northern right whale dolphins have less white on their bodies than the Southern species.

Northern right whale dolphin are found as individuals, or in groups as large as 2000.[3] The group's average number is 110 in the eastern Pacific and 200 individuals in the west. The school often associates with Lagenorhynchus obliquidens, the Pacific White-sided Dolphin.[4]

This predator travels at speeds up to 30-40 kilometres per hour across the open ocean, never along shallow coasts. They can dive up to 200 metres in search of fish, especially lanternfish, and squid.[4] They are found in temperate to cold waters, 24 to 8 degrees celsius, from latitudes 51°N to 35°N between the west coast of North America and asian continent.

Targeting of this species by the whaling industry, for food, is recorded in the eighteenth century. Records from the late twentieth century show large numbers of Lissodelphis borealis were caught in drift nets, used for large scale squid fishing, which is estimated as having reduced the population by one to three quarters.[4] The current population trend is unknown, IUCN Redlist gives the conservation status as Least Concern.[1]

The species was first published by Titian Peale in 1848. The genus Lissodelphis, is placed within Delphinidae, the ocean dolphin family of cetaceans.[2] The epithet of the genus was derived from Greek lisso , smooth, and delphis,[6] the specific epithet, borealis, indicates the northern distribution. The common names for the species include northern right whale dolphin, northern right whale porpoise, snake porpoise, Pacific right whale porpoise.[7][5] Both species in the genus are also referred by the name right whale dolphin, a name derived from the right whales Eubalaena who also lack a dorsal fin.[6][8]

Behaviour

This species usually travel in groups of between 5 animals and 200. When travelling fast the group will look like they're bouncing along on the water, as they make low leaps together, sometimes travelling as far as 7 metres in one leap. They are timid animals, and usually avoid boats. These graceful swimmers may bow-ride sometimes, and are spotted occasionally doing acrobatics, such as breaching, belly-flopping, side slapping and lobtailing.

References

  1. ^ a b Hammond, P.S., Bearzi, G., Bjørge, A., Forney, K., Karczmarski, L., Kasuya, T., Perrin, W.F., Scott, M.D., Wang, J.Y., Wells, R.S. & Wilson, B. (2008). Lissodelphis borealis. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 24 March 2009. Database entry includes a brief justification of why this species is of least concern.
  2. ^ a b Lissodelphis borealis (Peale, 1848) (TSN 180454). Integrated Taxonomic Information System.
  3. ^ a b c Jefferson, Thomas A.; Newcomer, M. (23 April, 1993). "Lissodelphis borealis". Mammalian Species (The American Society of Mammalogists) (425): 1–6. http://www.science.smith.edu/departments/Biology/VHAYSSEN/msi/pdf/i0076-3519-425-01-0001.pdf.  
  4. ^ a b c d e f "Lissodelphis borealis Right Whale Dolphin". MarineBio. http://marinebio.org/species.asp?id=352. Retrieved 2009-07-15.  
  5. ^ a b "Lissodelphis borealis (Peale, 1848)". discoverlife.org. Smithsonian Institution. http://www.discoverlife.org/mp/20q?search=Lissodelphis+borealis. Retrieved 2009-07-15.  
  6. ^ a b Fertl, Dagmar. "Southern right whale dolphin". Whales & Whale Spotting. http://library.thinkquest.org/C0124382/new_page_17.htm. Retrieved 2009-07-16.  
  7. ^ "Lissodelphis borealis (Peale, 1848)". Encyclopedia of life. eol.org. http://www.eol.org/pages/328527. Retrieved 2009-07-15.  
  8. ^ "Lissodelphis peronii". Species Profile and Threats Database. Department of the Environment, Water, Heritage and the Arts, Canberra.. http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=44. Retrieved 2009-07-16.  
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