Orcaella
| Orcaella | ||||||||||||
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Irrawaddy dolphin ( Orcaella brevirostris ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Orcaella | ||||||||||||
| Gray , 1866 |
Orcaella is a genus of dolphins (Delphinidae). The genus includes two species, the Irrawaddy Dolphin ( Orcaella brevirostris ), which occurs on the coasts of tropical Southeast Asia from the coast of theBay of Bengal to the Great Sunda Islands , and the Australian Snub Fin Dolphin ( Orcaella heinsohni ), which occurs east of it on the coasts New Guinea and northern Australia is home to. The snub-fin dolphin was originally considered a population of the Irrawaddy dolphin and was not described again until 2005.
features
Both species of dolphins are about 2.70 meters long, are almost uniformly gray in color, with a lighter belly side, without a beak-like elongated snout and thus more similar to the porpoises (Phocoenidae). The porpoise ( Neophocaena phocaenoides ), which occurs in the same area as the Irrawaddy dolphin, can be distinguished by the presence of a small fin , which the porpoise lacks.
The head profile of both species is rounded and is characterized by the large, round melon . The corners of the mouth are bent up so that the impression of a "smile" is created. The head and body are often separated by a conspicuous neck furrow.
The fin of both species sits on the middle of the back, is strong, but not particularly high. In both Orcaella species, the rear edge of the fin is often damaged. The flippers are spatulate, the front edge curved and the tip rounded. The fluke is small, notched in the center on the concave rear edge, and has pointed ends.
Way of life
While the snub fin dolphin only occurs in the sea near the coast, the Irrawaddy dolphin also lives in fresh waters and was found in the Irrawaddy 1500 km upstream and in the Mekong 690 km from the mouth. Also in Kalimantan there are populations in rivers and lakes over 500 km inland. Both species live in small groups, are shy and not particularly active animals compared to other dolphins.
literature
- Hadoram Shirihai : marine mammals. All 129 species worldwide. Illustrated by Brett Jarett. Franckh-Kosmos Verlags GmbH, Stuttgart 2008, ISBN 978-3-440-11277-9 .
