Irrawaddy Dolphin – Smiling Face of the Mekong


Conservation Status: ENDANGERED
Common name: Irrawaddy dolphine
Scientific name: Orcaella brevirostris
Type: Mammal
Diet: bony fish, crustaceans, cephalopods and fish eggs
Length: 2.3 – 2.75 m
Weight: 90 – 200 kg

These dolphins are mainly found in Southeast Asian estuaries and mangrove areas, as well as in river systems. Three subpopulations of the Irrawady dolphin, including those in the Mekong and the Ayeyarwady, are already Critically Endangered and close to extinction. Although they are not directly hunted or caught, they are caught accidentally as by-catch when they become entangled in nets. Habitat loss and degradation are also major threats to this species.

The Irrawaddy dolphin is similar to the beluga in appearance, though most closely related to the killer whale. It has a large melon and a blunt, rounded head, and the beak is indistinct. The dorsal fin, located about two-thirds posterior along the back, is short, blunt, and triangular. The flippers are long and broad. It is lightly coloured all over, but slightly more white on the underside than the back. Unlike any other dolphin, the Irrawaddy’s u-shaped blowhole is placed on the left of the midline and opens towards the front of the dolphin. Their short beaks appear very different than those of other dolphins, and their mouths are known for having 12-19 peg-like teeth on each side of their jaws. Irrawaddys can range from 90 kg (200 lb) to 200 kg (440 lb) and length is 2.3 m (7.5 ft) at full maturity. Maximum recorded length is 2.75 m (9.0 ft) of a male from Thailand.

Overall, the Irrawaddy dolphins’ colour is grey to dark slate blue, paler underneath, with no distinctive pattern. The dorsal fin is small and rounded behind the middle of the back. The forehead is high and rounded; the beak is lacking. The front of its snout is blunt. The flippers are broad and rounded. The finless porpoise (Neophocaena phocaenoides) is similar and has no back fin; the humpback dolphin (Sousa chinensis) is larger, has a longer beak and a larger dorsal fin.


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