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| Irrawaddy Dolphin
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| Orcaella brevirostris Gray, 1866 | ||||||||||||||
Irrawaddy Dolphin range
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The Irrawaddy Dolphin (Orcaella brevirostris) is a species of dolphin found near coasts and in estuaries in parts of south-east Asia.
The Irrawaddy Dolphin was identified by Owen in 1866 and is the only species in its genus. It is similar to the beluga in appearance. It has sometimes been listed in either a family containing just itself and in Monodontidae and Delphinapteridae . Nowadays there is widespread agreement to list it in the Delphinidae family
Genetically the Irrawaddy Dolphin is closely related to the Orca. The species name breviorstris comes from the Latin brevis meaning short.
This species has a large melon and a blunt, rounded head. Its beak is indistinct. The dorsal fin is short, blunt and triangular. It is located about two-thirds of the way along the back. The flippers are long and broad. It is lightly coloured all over - slightly more white on the underside than the back. It appears whiter than it actually is when set against the background of a muddy river.
Length is about 1 m at birth and 2.3 m at full maturity. Birth weight is about 10 kg. Adult weight exceeds 130 kg. Lifespan is about 30 years.
The Irrawaddy Dolphin is a slow swimmer. It surfaces in a rolling fashion and lifts its tail fluke clear of the water for a deep dive only. Irrawaddy Dolphins spit streams of water from their mouths whilst spyhopping. Dolphins of the species kept in captivity have been trained to do this on demand.
Although sometimes called the Irrawaddy River Dolphin, it is not a true river dolphin but an oceanic dolphinSee text Oceanic dolphins are the members of the Delphinidae family of cetaceans. These aquatic mammals are related to whales and porpoises. As the name implies, these dolphins tend to be found in the open seas, unlike the river dolphins, although a few s that lives near coasts and enters rivers, including the Ganges and the MekongThe Mekong is one of the world's major rivers. It is the 12th longest in the world, and the 10th largest by volume (discharging 475 km³ of water annually). It drains an area of 795,000 km²: from Tibet it runs through China's Yunnan province, Myanmar, Thai as well as the IrrawaddyThe Irrawaddy (newer spelling Ayeyarwaddy is a river that flows through the centre of Myanmar (formerly "Burma"). It is Myanmar's most important commercial waterway. Its total drainage area is about 158,700 square miles (411,000 square km). It is about 1, from which it takes its name. Its range extends from the Bay of BengalThe Bay of Bengal is a sea that forms the northeastern part of the Indian Ocean. It resembles a triangle in shape, and is bordered on the east by the Malay Peninsula, and on the west by the Indian subcontinent. On the northern tip of the "bay" lie the Ind to New GuineaNew Guinea located just north of Australia, is the world's second largest island having become separated from the Australian mainland when the area now known as the Torres Strait flooded around 5000 BC. The name Papua also refers to the island in whole or and northern AustraliaAustralia is the sixth-largest country in the world (geographically), the only one to occupy an entire continent, and the largest in the region of Australasia. Australia includes the island of Tasmania, which is an Australian State. Its neighbouring count.