THE IRRAWADDY DOLPHIN (Orcealla brevirostris)
External Features: The Irrawaddy dolphin is a small dolphin. One of over 80 known species of cetaceans (whales, dolphins and porpoises).
They have a blunt, bulbous forehead and are dark grey in colouration. The dorsal fin is situated three quarters back on the body and is small and rounded in shape
Maximum length recorded is 2.75 m. Maximum age recorded is 26 years.
Biology: Irrawaddy dolphins reach sexual maturity at 7-9 years of age and give birth to one calf every 2-3 years.
Feeding: Irrawaddy dolphins have been found to be a generalist feeders, taking a wide range of crustaceans (prawns and isopods), cephalopods (squid, cuttlefish and octopus) and bony fish.
Behaviour: A unique behaviour which you may observe is the dolphins spitting water. The exact reason for this behaviour is unknown, however, it always occurs while the dolphins are feeding and may be a method to herd fish.
It is often possible to see large fishing jumping as the dolphins are chasing them. After a short time you may hear a very loud sound which results in the fish being stunned, often floating on the water surface, where the dolphin can easily retrieve it. It is not yet known what produces this loud sound which is able to stun the fish.
Irrawaddy dolphins are slow, leisurely swimmers, which are shy of boats.