Irrawaddy dolphin  (Orcaella brevirostris)

A particularly distinctive dolphin, the Irrawaddy has a rounded head with no beak and a flexible neck, causing visible creases behind the head (2). Although most closely related to the orca (4), the Irrawaddy dolphin is similar in body form to the beluga whale, but darker in colour, with a pale to dark grey back and a light underside. The dorsal fin is small, triangular and rounded, and the flippers are long and broad (2).