Irrawaddy Dolphin

Overview

The Irrawaddy dolphin (Orcaella brevirostris) is a distinctive, beakless cetacean known for its rounded forehead and expressive, smiling mouthline. These dolphins are primarily found in shallow coastal waters, estuaries, and specific river systems across South and Southeast Asia, often relying on areas with freshwater influence.

Distribution & habitat

This species inhabits tropical and subtropical Indo-Pacific waters, ranging from the Bay of Bengal to northern Australia and New Guinea. While they are frequently found in coastal, brackish environments, they also maintain isolated freshwater populations in major rivers such as the Ayeyarwady, Mahakam, and Mekong. In these riverine habitats, they often congregate in deep pools, particularly during the dry season.

Appearance

Irrawaddy dolphins are robust with a slate-blue to slate-gray coloration and a lighter underside. They lack the elongated beak typical of many dolphins and possess a flexible neck that creates visible creases behind the head. Their dorsal fin is small and triangular with a rounded tip, positioned about two-thirds of the way down the back. They also feature broad, paddle-like pectoral fins.

Biology & behavior

These dolphins are generally social but not highly active at the surface, typically traveling in small groups of fewer than six individuals. They are known for their unique habit of spitting water, which may help them herd prey. In some regions, they have been observed engaging in cooperative fishing with local human communities, herding fish toward nets.

Feeding

As top predators in their ecosystems, they consume a varied diet of bony fish, cephalopods, and crustaceans. They utilize echolocation to locate prey and often hunt in groups, sometimes circling their targets to improve capture success.