Irrawaddy Dolphin
Orcaella brevirostris

Other Names: Snubfin Dolphin

Habitat: Inshore and riverines

Status: Locally common

Population: Unknown

Threats: Habitat destruction, human disturbance, entanglement in fishing nets, and hunting/whaling

Group Size: 2-10

Fin Position: Slightly behind center

Newborns: 35-39 in 990 cm-1 m), 26 lb (12 kg)

Adults: 7-8 ½ ft (2.1-2.6 m), 200-300 lb (90-150 kg)

Diet: Fish, and occasionally squid or octopus and krill or other crustaceans

Teeth: 34-40 on top row, 30-36 on bottom row

Description

Dorsal fin:

- blunt tip
- small, slightly triangular dorsal fin

Flukes:

- broad flukes
- distinct notch in middle
- slightly concave trailing edges
- raised above surface on deep dive

Flippers:

- strongly curved leading edges
- long, broad, spatulate or pointed flippers

Head:

- straight mouth line
- indistinct beak
- large melon
- blunt, rounded head
- mouth line changes shape
- some animals quite dark
- neck crease and slight depression at neck
- flexible neck

Other characteristics:

- bluish gray upper side
- narrow tail stock
- light underside appears almost white in muddy water
- streamlined but rounded body

Behavior

- slow, leisurely swimmer
- surfaces with a smooth, slow roll
- dives last 30 to 60 seconds, usually followed by 3 breaths in rapid succession; capable of diving for up to 12 minutes when frightened
- normally shows little of itself at the surface, but occasionally spyhops, lobtails, and breaches, making low, horizontal leaps, not quite clear of the water
- arches its tail stock on a deep dive
- may "spit" water from the mouth when spyhopping
- blow is normally invisible
- not known to bow-ride
- reported to cooperate with fishermen in Irrawaddy and Mekong rivers by diving fish into nets

Distribution

- warm coastal waters and rivers from the Bay of Bengal to Northern Australia
- mainly found n shallow coastal waters of the tropical Indo-Pacific but also in major river systems, especially: Brahmaputra and Ganges, India; Mekong, Vietnam, Laos, and Cambodia; Mahakam, Borneo; and Irrawaddy, Myanmar
- sometimes travels more than 805 (1,300 km) upstream; some individuals probably spend all their lives in fresh water
- along the coast it seems to prefer sheltered areas, such as turbid estuaries and mangrove swamps, and not yet found more than a few miles offshore
- probably occurs in Northern Australia and possibly the Philippines


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This page was created by:Candice Orca Mottet