The
Dusky Dolphin (
Lagenorhynchus obscurus) is a highly gregarious and acrobatic
dolphinDolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in seventeen genera. They vary in size from and , up to and . They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly...
found in coastal waters in the
Southern HemisphereThe Southern Hemisphere is the half of a planet that is south of the equator—the word hemisphere literally means 'half ball'...
. It was first identified by
John Edward GrayJohn Edward Gray was a British zoologist. He was the elder brother of George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray ....
in 1828. It is very closely
geneticallyGenetics, , a discipline of biology, is the science of heredity and variation in living organisms. The fact that living things inherit traits from their parents has been used since prehistoric times to improve crop plants and animals through selective breeding...
related to the
Pacific White-sided DolphinThe Pacific White-sided Dolphin is a very active dolphin found in the cool to temperate waters of the North Pacific Ocean.-Taxonomy:...
, but current scientific consensus is that they are distinct species.
Though the Dusky and Pacific White-sided Dolphins are traditionally placed in the genus
Lagenorhynchus, recent
molecularMolecular phylogenetics, also known as molecular systematics, is the use of the structure of molecules to gain information on an organism's evolutionary relationships. The result of a molecular phylogenetic analysis is expressed in a phylogenetic tree....
analyses indicate that they are more closely related to the dolphins of the genus
CephalorhynchusCephalorhynchus is a genus in the dolphin family Delphinidae. It consists of four species:A recent phylogenetic analysis by May-Collado & Agnarsson indicates that two species traditionally assigned to the genus Lagenorhynchus, the Hourglass Dolphin L. cruciger and Peale's Dolphin L...
.
The
Dusky Dolphin (
Lagenorhynchus obscurus) is a highly gregarious and acrobatic
dolphinDolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in seventeen genera. They vary in size from and , up to and . They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly...
found in coastal waters in the
Southern HemisphereThe Southern Hemisphere is the half of a planet that is south of the equator—the word hemisphere literally means 'half ball'...
. It was first identified by
John Edward GrayJohn Edward Gray was a British zoologist. He was the elder brother of George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray ....
in 1828. It is very closely
geneticallyGenetics, , a discipline of biology, is the science of heredity and variation in living organisms. The fact that living things inherit traits from their parents has been used since prehistoric times to improve crop plants and animals through selective breeding...
related to the
Pacific White-sided DolphinThe Pacific White-sided Dolphin is a very active dolphin found in the cool to temperate waters of the North Pacific Ocean.-Taxonomy:...
, but current scientific consensus is that they are distinct species.
Taxonomy
Though the Dusky and Pacific White-sided Dolphins are traditionally placed in the genus
Lagenorhynchus, recent
molecularMolecular phylogenetics, also known as molecular systematics, is the use of the structure of molecules to gain information on an organism's evolutionary relationships. The result of a molecular phylogenetic analysis is expressed in a phylogenetic tree....
analyses indicate that they are more closely related to the dolphins of the genus
CephalorhynchusCephalorhynchus is a genus in the dolphin family Delphinidae. It consists of four species:A recent phylogenetic analysis by May-Collado & Agnarsson indicates that two species traditionally assigned to the genus Lagenorhynchus, the Hourglass Dolphin L. cruciger and Peale's Dolphin L...
. If true, this would mean that these two species must either be transferred to
Cephalorhynchus or be given a new genus of their own genus that has been proposed for these species is
SagmatiasSagmatias is a genus that has been proposed for certain dolphin species that are currently placed in the genus Lagenorhynchus. Mitochondrial DNA studies have indicated that certain dolphin species within Lagenorhynchus are actually more closely related to dolphins within the genus Cephalorhynchus...
.
Physical description
The Dusky Dolphin is small to medium in length in comparison with other species in the family. There is significant variation in size among the different population areas. The largest Duskies have been encountered off Peru, where they are up to 210 cm (6 feet) in length and 100 kg (210 pounds) in mass. The back of the dolphin is dark grey or black and
dorsal finA dorsal fin is a fin located on the backs of some fish, whales, dolphins, and porpoises, as well as the ichthyosaurs. Depending on the species, an animal can have up to three of them. Its main purpose is to stabilize the animal against rolling and assist in sudden turns...
is distinctively two-toned—the leading edge matches the back in color, but the trailing edge is a much lighter greyish white. Duskies have a long, light grey patch on their foreside leading to a short, dark grey beak. The throat and belly are white. There are two blazes of white colour running back on the body from the dorsal fin to the tail. Right between the white areas remains a characteristic thorn-shaped patch of dark colour, by which the species can easily be recognized. Aside from that, Dusky Dolphins may be confused with other members of their
genusIn biology, a genus is a taxonomic unit used in the classification of living and fossil organisms. The term comes from Latin genus "descent, family, type, gender" , cognate with – genos, "race, stock, kin" ..In addition, genus is a taxonomic rank in the hierarchy In biology, a genus (plural:...
when observed at sea.
Population and distribution
The population of Dusky Dolphins is unknown, but authorities do not fear for the survival of the species at the moment. The Dusky Dolphin is distributed in coastal waters of
ChileChile, officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
,
ArgentinaArgentina, officially the Argentine Republic , is the second largest country in South America, constituted as a federation of 23 provinces and an autonomous city, Buenos Aires. It is the eighth largest country in the world by land area and the largest among Spanish-speaking nations, though Mexico,...
and the Malvinas Islands,
NamibiaNamibia, officially the Republic of Namibia , is a country in Southern Africa whose western border is the Atlantic Ocean. It shares borders with Angola and Zambia to the north, Botswana and Zimbabwe to the east, and South Africa to the south and east...
and the west coast of
South AfricaThe Republic of South Africa is a country located at the southern tip of Africa, with a coastline on the Atlantic and Indian Oceans. To the north lie Namibia, Botswana and Zimbabwe, to the east are Mozambique and Swaziland, while Lesotho is an independent country surrounded by South Africa.Modern...
and all around
New ZealandNew Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses , and numerous smaller islands, most notably Stewart Island/Rakiura and the Chatham Islands. The indigenous Māori named New Zealand Aotearoa, commonly translated as The Land of the Long White Cloud...
. There may also be resident populations off
TasmaniaTasmania is an Australian island and state. It is located south of the eastern side of the continent, from which it is separated by Bass Strait. The state includes the island of Tasmania – the 26th largest island in the world – and the surrounding islands. The state has a population of 500,000 ,...
and
New South WalesNew South Wales is Australia's most populous state, located in the south-east of the country, north of Victoria, south of Queensland and east of South Australia...
and several small islands in the South Atlantic and
Indian OceanThe Indian Ocean is the third largest of the world's oceanic divisions, covering about 20% of the water on the Earth's surface. It is bounded on the north by South Asia ; on the west by Africa; on the east by Indochina, the Sunda Islands, and Australia; and on the south by the Southern Ocean...
s. An aerial survey off
PatagoniaPatagonia is a geographic region containing the southernmost portion of South America. Located in Argentina and Chile, it comprises the southernmost portion of the Andes mountains to the west and south, and plateaux and low plains to the east. The name Patagonia comes from the word patagón used by...
in the mid-1990s indicated that there was a local population in excess of 7,000 individuals. Duskies can move over great distances (one individual had a confirmed range of 780
nautical mileThe nautical mile is a unit of length corresponding approximately to one minute of arc of latitude along any meridian....
s) (1,440 km). However it is not believed that they follow a migatory pattern.
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