Commerson Dolphin
| Commerson Dolphin | ||||||||||||
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Commerson Dolphin |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Cephalorhynchus commersonii | ||||||||||||
| ( Lacépède , 1804) |
The high-contrast Commerson dolphin ( Cephalorhynchus commersonii ), also known as Jacobita or Tonina , lives in the coastal waters around Tierra del Fuego and the Falkland Islands . There is also a second, separate population around the Kerguelen Islands in the Indian Ocean .
features
The Commerson Dolphin shows a striking black and white body color. A white, sharply contoured band runs diagonally around the entire body, at the top from the neck to just before the fin , at the bottom from behind the flippers to the beginning of the tail. The throat has a white spot and a dark spot on the belly, which is drop-shaped in females and a horseshoe-shaped in males. The head is conical with a slightly sloping forehead and without a conspicuous snout. The upper jaw has 56 to 68 teeth, the lower jaw 52 to 70 teeth. With a body length of only 1.3 to 1.7 meters, the Commerson dolphins are among the smallest whales in the world, and they can weigh 35 to 60 kilograms. The fin is rounded and has a slightly concave back. The flippers are round and black on both sides, the left one has a jagged front edge. The fluke is concave and has a slight indentation in the middle. Newborns are 55 to 75 cm long, weigh about 6 kg, and are gray, black, and brown in color.
behavior
In small schools of mostly less than 10 animals, they hunt together fish, squid , krill and other crustaceans . Jacobita dolphins are fast swimmers who often jump out of the water and enjoy riding the bow waves of ships.
distribution and habitat
The species occurs in two separate populations . The larger population can be found on the coasts of Argentina , in the Strait of Magellan and around the Falkland Islands . The second population lives about 8,000 kilometers away on the Kerguelen . The Commerson Dolphin prefers shallow coastal areas.
Hardly anything can be said about their population, but like many other small whales , they often end up in fishing nets as unwanted bycatch . The species is currently not considered threatened.
Systematics
Internal system
The nominate form in South America and a population on the Kerguelen in the southern Indian Ocean form the two recognized subspecies of the Commerson dolphin. A single individual has been sighted near South Africa, which is several thousand kilometers away from both habitats.
- Cephalorhynchus commersonii commersonii lives around the southernmost point of South America and forms the much larger main population of the species. Its black and white contrasting drawing is clearly delineated.
- Cephalorhynchus commersonii kerguelenensis lives around the Kerguelen. Only a few animals belong to this subspecies, which is why it is listed as critically endangered in the IUCN regional red list for the French southern and Arctic regions . It is slightly larger than the animals of the nominate form and its pattern is significantly paler or rather dark gray-light gray. Because of the small number of individuals, this population is particularly susceptible to impairment by humans.
External system
The Commerson dolphins belong to the genus of black and white dolphins ( Cephalorhynchus ). Your closest relatives are:
- White-bellied dolphin ( Cephalorhynchus eutropia )
- Heaviside dolphin ( Cephalorhynchus heavisidii )
- Hector's dolphin ( Cephalorhynchus hectori ) with the Maui dolphin ( C. hectori maui ) as a subspecies
All types of black and white dolphins are physically very small, their head length is between 110 and 180 cm, their weight between 26 and 86 kg.
proof
- Mark Carwardine : Whales and Dolphins . Delius Klasing, Bielefeld 2008, ISBN 978-3-7688-2473-6 , p. 198-199 .
Web links
- Cephalorhynchus commersonii in the endangered Red List species the IUCN 2006. Posted by: Cetacean Specialist Group, 1996. Retrieved on 12 May, 2006.