Today: Saturday 19 June 2021 , 11:40 pm


advertisment
search




Commerson's dolphin

Last updated 1 Month , 4 Day 12 Views

Advertisement
In this page talks about ( Commerson's dolphin ) It was sent to us on 16/05/2021 and was presented on 16/05/2021 and the last update on this page on 16/05/2021

Your Comment


Enter code
 
{{Speciesbox
name = Commerson's dolphin
image = Commdolph01.jpg
image_caption = A Commerson's dolphin in an aquarium.
image2 = Commerson's dolphin size.svg
image2_caption = Size compared to an average human
status = LC
status_system = IUCN3.1
status_ref =Crespo, E., Olavarria, C., Dellabianca, N., Iñíguez, M., Ridoux, V. & Reeves, R. 2017. Cephalorhynchus commersonii (errata version published in 2018). The IUCN Red List of Threatened Species 2017: e.T4159A128963283. Downloaded on 30 December 2018.
genus = Cephalorhynchus
species = commersonii
authority = Lacépède, 1804
range_map = Commerson's dolphin South America distribution.png
range_map_caption = C. c. commersonii distribution near South America
range_map2 = Commerson's dolphin Kerguelen Island distribution.png
range_map2_caption = C. c. kerguelensis distribution near the Kerguelen Islands
subdivision_ranks = Subspecies
subdivision =
  • C. c .commersonii
  • C. c .kerguelensis

Commerson's dolphin (Cephalorhynchus commersonii), also referred to by the common names jacobita, skunk dolphin, piebald dolphin or panda dolphin, is a small oceanic dolphin of the genus Cephalorhynchus. Commerson's dolphin has two geographically-isolated but locally-common subspecies. The principal subspecies, C.c.commersonii, has sharply-delineated black-and-white patterning and is found around the tip of South America. The secondary subspecies, C.c.kerguelenensis, is larger than C.c.commersonii, has a less-sharply delineated dark and light grey patterning with a white ventral band, and is found around the Kerguelen Islands in the Indian Ocean.
The dolphin is named after French naturalist Dr Philibert Commerson, who first described them in 1767 after sighting them in the Strait of Magellan.Sharks and Whales (Carwardine et al. 2002), p. 370.

Population and distribution

Two disjunct subspecies of the dolphin are found in geographically disparate areas separated by 130° of longitude and about ; it is not known why they are thus distributed. Global populations are unknown, but the species is accepted to be locally common.
The main subspecies, C.c.commersonii, is found inshore in various inlets in Argentina including Puerto Deseado, in the Strait of Magellan and around Tierra del Fuego, and near the Falkland Islands (Las Malvinas). A survey in 1984 estimated there to be 3,400 individuals in the Strait of Magellan.
Dolphins of the second subspecies, C.c.kerguelenensis, were discovered in the 1950s. They reside near the Kerguelen Islands in the southern part of the Indian Ocean, and prefer shallow waters.
In 2004, a vagrant individual of unconfirmed origin was sighted on South Africa's Agulhas Bank, a location from the Kerguelen Islands and from South America. Though the Kerguelen Islands are closer, such a journey would require swimming against the Antarctic Circumpolar Current.

Description

C.c.commersonii


The commersonii subspecies 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 southern Patagonia, at 23 kg (51 lb) and 1.36 m (4.5 ft), may be the smallest adult cetacean on record.Wood, The Guinness Book of Animal Facts and Feats. Sterling Pub Co Inc. (1983), 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 edge is typically concave, but not falcate. The fluke has a notch in the middle. This dolphin has no rostrum.
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 during the spring and summer. The Commerson's dolphin has been known to live up to eighteen years in the wild, while in captivity the oldest individual was at least 33 years old at the time of death.

C.c.kerguelenensis


Dolphins of the kerguelenensis subspecies tend to be larger than those of C.c.commersonii, and differ in patterning in that they are dark grey instead of black, and light grey instead of white, except ventrally. The demarcation between areas of the pattern is also less clearly demarcated.

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. Individuals have been recorded as entering the Santa Cruz River to forage there during low tide.

Conservation

The IUCN lists Commerson's dolphin as Least Concern 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.
The Commerson's dolphin population of South America is listed on Appendix II"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. of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). It is listed on Appendix II as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.

Captivity

These dolphins have been known to be displayed in a few aquariums.

See also


  • List of cetaceans

    • National Audubon Society: Guide to Marine Mammals of the World
    • Encyclopedia of Marine Mammals
    • The Sierra Club Handbook of Whales and Dolphins

    External links


    Heaveside's dolphin
    Category:Mammals of Argentina
    Category:Mammals of Chile
    Category:Marine fauna of South America
    Category:Cetaceans of the Atlantic Ocean
    Category:Cetaceans of the Indian Ocean
    Category:Fauna of Patagonia
    Category:Fauna of Tierra del Fuego
    Category:Fauna of the Kerguelen Islands
    Category:Southeastern South American coastal fauna
    Commerson's dolphin
    Commerson's dolphin
     
    Comments

    There are no Comments yet




    last seen
    Most vists