Irrawaddy Dolphin

The Irrawaddy dolphin is a slate-blue to grey dolphin, paler underneath and without a distinct pattern, with a blunt snout. It weighs 90–200 kg and reaches about 2.3 m at full maturity. It surfaces in a rolling way and lifts its tail fluke clear of the water only for a deep dive. It closely resembles the Australian snubfin dolphin, which was described as a separate species only in 2005 (Wikipedia, general species account).

It lives in scattered subpopulations near coasts and in estuaries and rivers in the Bay of Bengal and Southeast Asia. One of only two concentrated lagoon populations is at Chilika Lake in Odisha, where 156 were counted in 2021; Bangladesh has about 3,500 in coastal waters and 451 in the Sundarbans. Groups are usually two or three, sometimes up to 25 in deep pools. It can squirt streams of water up to 1.5 m, apparently to herd fish, and gestation is about 14 months (Wikipedia, general species account).