Short-snouted dolphins
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| Gray , 1846 |
The short- snouted dolphins ( Lagenorhynchus ) are a genus of dolphins that are characterized by a beak that is not so clearly separated from the head. They usually have small distribution areas and can be quite common regionally, but are of less global importance than, for example, common dolphin , bottlenose dolphin and spotted dolphin .
features
Depending on the species, short-snouted dolphins are between 150 and 310 cm long. The color is mostly dark gray or black on the top, lighter on the underside and striped on the side.
Way of life
While dolphins are commonly associated with tropical latitudes, these species are most common in cold and temperate waters. Three species live in the northern and three in the southern hemisphere. With the white-stripe and the black dolphin, two species belong to the genus, which also perform acrobatic jumps under natural conditions; But this does not apply to all species, so white-snouted and white-sided dolphins do not jump at all.
The food of the short-snouted dolphins consists mainly of fish (especially herring , mackerel , anchovies , hake ), as well as cephalopods, crustaceans and mollusks. All species live in schools that vary greatly in size: most contain six or slightly more individuals, but some can consist of over a thousand animals.
Short-snouted dolphins are common, and no significant decline in populations is known of any species.
Systematics
It is possible that the short -snouted dolphins are a polyphyletic group and four species are more or less closely related to the black-and-white dolphins ( Cephalorhynchus ), while the white-sided dolphins ( Lagenorhynchus acutus ) have a basal position as a sister species of the subfamilies Delphininae (genera Delphinus , Stenella and others) and Stenoninae (genera Sotalia and Steno ).
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Phylogenetic systematics of the Delphinidae according to Horreo 2018
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Genetic studies show the short -snouted dolphins as a sister group to the black and white dolphins ( Cephalorhynchus ) and the killer whale ( Orcinus orca ) is considered to be a sister species of these two . Together, these species are the subfamily Globicephalinae with the pilot whales ( Globicephala ), the pygmy killer whale ( Feresa attenuata ) and the Breitschnabel dolphin ( Peponocephala Electra ), the little Orca ( Pseudorca crassidens ) and the Risso ( Grampus griseus ) and the two species of the genus Orcaella faced .
The types are:
- White-beaked dolphin ( Lagenorhynchus albirostris ), northern Atlantic
- White-sided dolphin ( Lagenorhynchus acutus ), northern Atlantic
- White- striped dolphin ( Lagenorhynchus obliquidens ), northern Pacific
- Black dolphin ( Lagenorhynchus obscurus ), temperate seas of the southern hemisphere
- Peale dolphin ( Lagenorhynchus australis ), temperate seas off South America
- Hourglass dolphin ( Lagenorhynchus cruciger ), Southern Ocean
supporting documents
- ↑ Laura May-Collado, Ingi Agnarsson: Cytochrome b and Bayesian inference of whale phylogeny. Molecular Phylogenetics and Evolution (2006) PDF
- ↑ a b c José L. Horreo: New insights into the phylogenetic relationships among the oceanic dolphins (Cetacea: Delphinidae). Journal of Zoological Systematics and Evolutionary Research 57 (2), May 2019; Pp. 476-480. doi : 10.1111 / jzs.12255
literature
- Ronald M. Nowak: Walker's Mammals of the World . Johns Hopkins University Press, 1999 ISBN 0801857899
