Irrawaddy Dolphin

Description

The Irrawaddy Dolphin has a distinctive round head with a blunt snout and no beak — resembling a beluga whale more than a typical dolphin. It can change facial expression, appearing to pucker its lips and squirt water — a behavior used in feeding and social interaction. Grey overall, slightly paler on the underside.

Senses

Well-developed echolocation for hunting in turbid riverine and coastal environments. Notably flexible neck allows significant head movement compared to most dolphins.

Communication

Irrawaddy Dolphins produce clicks, burst-pulse sounds, and whistles. They are among the few delphinids that can squirt water from their mouths — used in a form of 'herding' behavior to concentrate fish toward the surface.

Hunting & Diet

Uses a unique spit-feeding technique — squirting water from the mouth to herd fish. Also cooperates with artisanal fishermen in Myanmar and Cambodia, driving fish into nets in exchange for the fish that escape — a mutualistic relationship similar to that documented with Atlantic Humpbacked Dolphins.

Reproduction

Gestation

14 months. Females give birth every 2–3 years.

Birth

Calves are approximately 3 feet long and 22 lbs at birth.

Calves

Calves nurse for approximately 2 years and remain with their mothers for up to 3 years.

Sexual Maturity

Females reach sexual maturity at approximately 7–9 years; males at 8–10 years.

Social Structure

Found in groups of 2–6 individuals in freshwater populations; coastal populations may form larger groups of 10–15.

Athleticism & Speed

Slow, deliberate swimmers adapted to turbid, shallow environments. Frequently spy-hops and raises the head above water. Rarely leaps.

Unusual Facts

Irrawaddy Dolphins cooperate with traditional fishermen in both Myanmar and Cambodia — driving fish toward nets and being rewarded with escaped catch. Some individual dolphins have worked with the same families for multiple generations, suggesting cultural transmission of this cooperative behavior.

Lifespan & Threats

28–30 years. Freshwater populations are critically endangered: the Mekong population has under 100 individuals; the Mahakam has under 80. Threats include gillnet bycatch, electrofishing, dam construction, illegal fishing, boat traffic, and prey depletion.