World Library  
Flag as Inappropriate
Email this Article
 

Commerson's dolphin

Commerson's dolphin[1]
A Commerson's dolphin in an aquarium.
Size compared to an average human
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Subclass: Eutheria
Order: Cetacea
Suborder: Odontoceti
Family: Delphinidae
Genus: Cephalorhynchus
Species: C. commersonii
Binomial name
Cephalorhynchus commersonii
Lacépède, 1804
Subspecies
  • C.c.commersonii
  • C.c.kerguelensis
Commerson's dolphin distribution near South America
Commerson's dolphin distribution near Kerguelen Island

Commerson's dolphin (Cephalorhynchus commersonii) is one of four dolphins in the genus Cephalorhynchus. The species has also the common names skunk dolphin, piebald dolphin and panda dolphin. The dolphin is named for Philibert Commerson, who first described them in 1767 after he sighted them in the Strait of Magellan.[3]

Contents

  • Description 1
  • Population and distribution 2
  • Behavior 3
  • Conservation 4
  • Captivity 5
  • Current Status 6
  • See also 7
  • References 8
  • External links 9

Description

A Commerson's dolphin in the Strait of Magellan

Commerson's dolphin has a very distinctive patterning. It has a black head, dorsal fin, and fluke, with a white throat and body. The demarcation between the two colours is very clear-cut. This stocky creature is one of the smallest of all cetaceans growing to around 1.5 m (5 ft). A mature female caught off of south Patagonia, at 23 kg (51 lb) and 1.36 m (4.5 ft), may be the smallest adult cetacean on record.[4] Its appearance resembles that of a porpoise, but its conspicuous behaviour is typical of a dolphin. The dorsal fin has a long, straight leading edge which ends in a curved tip. The trailing is typically concave but not falcate. The fluke has a notch in the middle. This dolphin has no rostrum. It is not known why their distribution is limited to the southern coast of South America and the Kerguelen Islands.

Sexes are easily distinguished by the different shape of the black blotch on the belly — it is shaped like a teardrop in males but is more rounded in females. Females reach breeding age at six to 9 years. Males reach sexual maturity at about the same age. Mating occurs in the spring and summer and calving occurs after a gestation period of 11 months. The oldest known Commerson's dolphin died at age 18.

Population and distribution

The two disjunct subspecies are separated by 130° of longitude and about 8,500 km (5,300 mi). The larger population (C.c.commersonii) is found inshore in various inlets in Argentina, in the Strait of Magellan and near the Falkland Islands. The second subspecies (C.c.kerguelenensis, discovered in the 1950s) resides near the Kerguelen Islands. They prefer shallow waters. Global populations are unknown, but the species is accepted to be locally common. A survey in 1984 estimated there to be 3,400 individuals in the Strait of Magellan.

The dolphin is found in two geographically disparate areas:

A vagrant individual was sighted on the Agulhas Bank off South Africa in 2004. This specimen was isolated from the Kerguelen population by 4,200 km (2,600 mi) and from the South American by 6,300 km (3,900 mi). However, the Antarctic Circumpolar Current would force an individual from the Kerguelen population to swim against the West Wind Drift.[5]

Behavior

Commerson's dolphin is very active. It is often seen swimming rapidly on the surface and leaping from the water. It also spins and twists as it swims and may surf on breaking waves when very close to the shore. It will bow-ride and swim behind fast-moving boats. It is also known to swim upside-down, which is thought to improve the visibility of its prey.

This dolphin feeds on a mix of coastal and pelagic fish and squid. Those in the South American subpopulation supplement their diets with crustaceans.

Conservation

The IUCN lists Commerson's dolphin as Data Deficient in its Red List of Threatened Species. The proximity of the dolphin to the shore makes accidental killing in gillnets a common occurrence. The dolphin was killed for use as crab bait by some Argentinian and Chilean fishermen in the 1970s and 1980s, but this practice has since been curtailed.[2]

The Commerson's dolphin population of South America is listed on Appendix II[6] of the

[1]

  • Whale and Dolphin Conservation Society
  • The Delphinoidea Family

External links

  • National Audubon Society: Guide to Marine Mammals of the World ISBN 0-375-41141-0
  • Encyclopedia of Marine Mammals ISBN 0-12-551340-2
  1. ^ Mead, J.G.; Brownell, R.L., Jr. (2005). "Order Cetacea". In Wilson, D.E.; Reeder, D.M. Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. pp. 723–743.  
  2. ^ a b Reeves, R.R., Crespo, E.A., Dans, Jefferson, T.A., Karczmarski, L., Laidre, K., O’Corry-Crowe, G., Pedraza, S., Rojas-Bracho, L., Secchi, E.R., Slooten, E., Smith, B.D., Wang, JY. & Zhou, K. (2008). "Cephalorhynchus commersonii".  
  3. ^ Sharks and Whales (Carwardine et al. 2002), p. 370.
  4. ^ Wood, The Guinness Book of Animal Facts and Feats. Sterling Pub Co Inc (1983), ISBN 978-0-85112-235-9
  5. ^ Bruyn, P. J. N., de; Hofmeyr, G. J. G.; Villiers, M. S., de (2006). "First record of a vagrant Commerson’s dolphin, Cephalorhynchus commersonii, at the southern African continental shelf" (PDF). African Zoology 41 (1). Retrieved February 2015. 
  6. ^ a b "Appendix II" of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). As amended by the Conference of the Parties in 1985, 1988, 1991, 1994, 1997, 1999, 2002, 2005 and 2008. Effective: 5 March 2009.
  7. ^ Convention on Migratory Species page on the Commerson's dolphin

References

See also


A few are accidentally killed in gill nets set for crabs along the Argentine coast, and local fishermen may kill them for food. Several have been shipped abroad to aquariums. Commerson's dolphins also inhabit waters heavy with human activity, creating a large danger for them.11

Current Status

About two dozen Commerson's dolphins live in aquariums around the world, including SeaWorld San Diego, Aquatica in Florida, Duisburg Zoo in Germany (until 2004), and several aquariums in Japan.

Captivity

[7]

This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 



Copyright © World Library Foundation. All rights reserved. eBooks from World Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.