Concept
The Irrawaddy dolphin (Orcaella brevirostris) is a euryhaline species of oceanic dolphin found in scattered subpopulations near sea coasts and in estuaries and rivers in parts of the Bay of Bengal and Southeast Asia. It closely resembles the Australian snubfin dolphin (of the same genus, Orcaella), which was not described as a separate species until 2005. It has a slate blue to a slate gray color. Although found in much of the riverine and marine zones of South and Southeast Asia, the only concentrated lagoon populations are found in Chilika Lake in Odisha, India and Songkhla Lake in southern Thailand. One of the earliest recorded descriptions of the Irrawaddy dolphin was by Sir Richard Owen in 1866 based on a specimen found in 1852, in the harbour of Visakhapatnam on the east coast of India. It is one of two species in its genus. It has sometimes been listed variously in a family containing just itself and in the Monodontidae and Delphinapteridae. Widespread agreement now exists to list it in the family Delphinidae. The species name brevirostris is from the Latin meaning short-beaked. It is very closely related to the Australian snubfin dolphin (Orcaella heinsohni). The two snubfin dolphins were only recognised as separate species in 2005 when a genetic analysis showed that the population found along the coast of northern Australia forms a second species in the genus Orcaella. The Orcaella dolphins are close relatives of the oceanic dolphins in Globicephalinae subfamily. Vernacular names for the Irrawaddy dolphin include: โลมาอิรวดี loma irawadi, โลมาหัวบาตร loma hua bat ("alms-bowl dolphin", due to the shape of their heads) Odia: ଶିଶୁମାର sisumāra, ଭୁଆସୁଣୀ ମାଛ bhuāsuṇi mācha (lit. oil-yielding dolphin), lagoon area local name- ଖେରା kherā Tagalog: lampasut Bengali: শুশুক shushuko Kutai Malay: pesut mahakam, ikan pesut Khmer: ផ្សោត ph’sout Lao: ປາຂ່າ pa’kha Sarawak Malay: empesut, pesut Burmese: ဧရာဝတီ လင်းပိုင် eyawadi lăbaing The word pesut comes from hearing the sound made from the dolphin exhaling from its blowhole.