Peale's dolphin | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Artiodactyla |
Infraorder: | Cetacea |
Family: | Delphinidae |
Genus: | Lagenorhynchus |
Species: | L. australis |
Binomial name | |
Lagenorhynchus australis (Peale, 1848) | |
Peale's dolphin range |
Peale's dolphin (Lagenorhynchus australis) is a small dolphin found in the waters around Tierra del Fuego at the foot of South America. It is also commonly known as the black-chinned dolphin or even Peale's black-chinned dolphin. However, since Rice's work [3] Peale's dolphin has been adopted as the standard common name.
Though it is traditionally placed in the genus Lagenorhynchus, recent molecular analyses indicate Peale's dolphin is actually more closely related to the dolphins of the genus Cephalorhynchus . If true, this would mean this species must either be transferred to Cephalorhynchus or be given a new genus of its own. An alternate genus proposed for this species (as well as the Pacific white-sided dolphin, hourglass dolphin and dusky dolphin is the resurrected genus Sagmatias . [4] Some behavioral and morphological data support moving Peale's dolphin to Cephalorhynchus. According to Schevill & Watkins 1971, Peale's dolphin and the Cephalorhynchus species are the only dolphins that do not whistle. Peale's dolphin also shares with several Cephalorhynchus species the possession of a distinct white "armpit" marking behind the pectoral fin.
Peale's dolphin is of typical size in its family — about 1 m in length at birth and 2.1 m (6.9 ft) when fully mature. Its adult weight is about 115 kg. It has a dark-grey face and chin. The back is largely black with a single off-white stripe running curving and thickened as it runs down the back on each side. The belly is white. Conspicuously, also a white patch occurs under just behind each flippers. These are known as the "armpits". The flanks also have a large white-grey patch above the flipper. The dorsal fin is large for this size cetacean and distinctively falcated. The flippers themselves are small and pointed. The tail fin, too, has pointed tips, as well as a notch at its middle.
The species looks similar to the dusky dolphin when viewed at a distance, and may be confused with it.
Peale's dolphin is endemic to the coastal waters around southern South America. On the Pacific side, they have been seen as far north as Valdivia, Chile at 38°S. On the Atlantic side, sightings typically diminish at about 44°S — near Golfo San Jorge, Argentina. In the south, they have been seen at almost 60°S — well into the Drake Passage.
They are often found in areas of fast-moving waters, such as entrances to channels and narrows, as well as close to shore in safe areas such as bays.
The total population is unknown, but recent research estimates there to be ~21,800 individuals in the South Atlantic part of its range. [5]
Peale's dolphins congregate in small groups — usually about five in number, and sometimes up to 20. [6] On rare occasions in summer and autumn, much larger groups have been recorded (100 individuals). A typical pattern is for the group to move in a line parallel to the shore. They usually swim slowly, but are prone to bursts of activity. [5]
Peale's dolphins are often found swimming slowly near kelp beds. [6] [7] They have been found to associate with other cetaceans such as Commerson's dolphins. [7]
In the southwestern South Atlantic, Peale's dolphin forages in the coastal ecosystem, feeding mainly on the demersal and bottom fish such as southern cod and Patagonian grenadier; also octopus, squid, and shrimps have also been found in stomachs examined. They feed in or near kelp beds and in open waters, with cooperative feeding, such as straight-line and large circle formations or star-burst feeding in which large groups encircle prey. [7]
Peale's dolphins' propensity for moving over only small areas, and staying close to shore, has rendered them vulnerable to interference by man. During the 1970s and '80s, Chilean fisherman killed and used thousands of Peale's dolphins for crab bait each year. [5] [7] This practice has decreased, but not been made illegal. [5] [7]
In Argentina, Peale's dolphins have been reported becoming trapped in gill nets, but the extent of this is not known. [5] Conservation groups such as the Whale and Dolphin Conservation demand further research be made into this species.
The Peale's dolphin or black-chinned dolphin is listed on Appendix II [8] of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). It is listed on Appendix II [8] as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements. [9]
The white-beaked dolphin is a marine mammal belonging to the family Delphinidae in the suborder Odontoceti.
The spectacled porpoise is a small to midsize porpoise indigenous to the Southern Ocean. It is one of the most poorly studied cetaceans, partly due to its remote range in the southern ocean. What little is known about this porpoise species has been gathered mainly from stranded individuals, and a few observations of living animals made at sea.
The Chilean dolphin, also known as the black dolphin, is one of four dolphins in the genus Cephalorhynchus. The dolphin is found only off the coast of Chile; it is commonly referred to in the country as tonina.
The dusky dolphin is a dolphin found in coastal waters in the Southern Hemisphere. Its specific epithet is Latin for "dark" or "dim". It is very closely genetically related to the Pacific white-sided dolphin, but current scientific consensus holds they are distinct species. The dolphin's range is patchy, with major populations around South America, southwestern Africa, New Zealand, and various oceanic islands, with some sightings around southern Australia and Tasmania. The dusky dolphin prefers cool currents and inshore waters, but can also be found offshore. It feeds on a variety of fish and squid species and has flexible hunting tactics. The dusky dolphin is known for its remarkable acrobatics, having a number of aerial behaviours. The status of the dolphin is unknown, but it has been commonly caught in gill nets.
Commerson's dolphin, also referred to by the common names jacobita, skunk dolphin, piebald dolphin, panda dolphin, or tonina overa, 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.
Heaviside's dolphin is one of four dolphins in the genus Cephalorhynchus. The small cetacean is endemic to the Benguela ecosystem along the southwest coast of Africa.
Cephalorhynchus is a genus in the dolphin family Delphinidae.
Fraser's dolphin or the Sarawak dolphin is a cetacean in the family Delphinidae found in deep waters in the Pacific Ocean and to a lesser extent in the Indian and Atlantic Oceans.
Lagenorhynchus is a genus of oceanic dolphins in the infraorder Cetacea, presently containing six extant species. However, there is consistent molecular evidence that the genus is polyphyletic and several of the species are likely to be moved to other genera. In addition, the extinct species Lagenorhynchus harmatuki is also classified in this genus.
The northern right whale dolphin is a small, slender species of cetacean found in the cold and temperate waters of the North Pacific Ocean. Lacking a dorsal fin, and appearing superficially porpoise-like, it is one of the two species of right whale dolphin.
The hourglass dolphin is a small dolphin in the family Delphinidae that inhabits offshore Antarctic and sub-Antarctic waters. This is one of very few species to be considered completely Antarctic, as it exclusively lives in Antarctic waters. It is commonly seen from ships crossing the Drake Passage, but has a circumpolar distribution.
The Atlantic white-sided dolphin is a distinctively coloured dolphin found in the cool to temperate waters of the North Atlantic Ocean.
The Pacific white-sided dolphin, also known as the hookfin porpoise, is an active dolphin found in the cool or temperate waters of the North Pacific Ocean.
Sagmatias was a genus of dolphins, defined in 1866 by Edward Drinker Cope with Peale's dolphin as type species, described as Sagmatias amblodon. It has been proposed to resurrect the genus to include four species of oceanic dolphins currently classified in the genus Lagenorhynchus. Mitochondrial DNA studies have indicated that Pacific white-sided dolphin, Peale's dolphin, dusky dolphin and hourglass dolphin are more closely related to dolphins in the Lissodelphininae subfamily, than to the two other members of the genus: Atlantic white-sided dolphin and white-beaked dolphin. This phylogenetic relationship is further supported by cladistic analysis of morphological characters. However, resurrection of the genus Sagmatias has not been accepted by the Society for Marine Mammalogy's taxonomic Committee, because the finer details of the phylogenetic relationships between the four species in the proposed Sagmatias genus and the four species of dolphins in the genus Cephalorhynchus remains to be resolved. Genetic and bioacoustical evidence suggest that Peale's dolphin and hourglass dolphin are closer related to the Cephalorhynchus species than to the Pacific white-sided dolphin and dusky dolphin, which, if true, would make the genus Sagmatias paraphyletic.
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