Indo-Pacific Hump-backed Dolphin
Sousa chinensis

Other Names: Indo-Pacific Humpback Dolphin, Speckled Dolphin, S. plumbea (animals west of Sumatra)

Habitat: Inshore

Status: Locally common

Population: Unknown

Threats: Hunting/whaling, entanglement in fishing nets, habitat destruction and pollution

Group Size: 3-7, small groups may congregate to form larger groups

Fin Position: Center

Newborns: c.39 in (1 m), c.55 lbs. (25 kg)

Adults: 6 ½-9 ¼ ft. (2-2.8 m), 330-440 lbs. (150-200 kg)

Diet: Fish

Teeth: 58-76 on both top and bottom rows

Description

Dorsal fin:

- elongated hump in middle of back (variable)
- small falcate or triangular dorsal fin sits on hump (variable)
- base of hump may be at least one-third of body length in some animals
- fin shape is more sickle-shaped in younger animals
- more concave trailing edge than in adults

Flukes:

- broad flukes
- distinct notch in middle
- concave trailing edges

Flippers:

- broad flippers with rounded tips

Head:

- slightly round melon
- tip of beak may lighten with age
- long, slender beak
- fairly straight mouth line

Other characteristics:

- brownish gray, pale gray, or pinkish white upper side
- distinctive keels below and above tail stock
- robust body
- underside usually lighter than sides and upper side
- body may be speckled

Behavior

- usually quite difficult to approach and tends to avoid boats by diving and reappearing some distance away in a different direction
- rarely bow-rides
- distinctive surfacing behavior: breaks surface at an angle of 30° to 45°, clearly showing beak and sometimes entire head, and a few seconds later arches back strongly and may lift flukes into the air
- surfaces about every 40 to 60 seconds but can stay underwater for several minutes
- normally a slow swimmer, but courtship may involve chasing one another around in circles at high speed
- may turn on one side and wave a flipper in the air
- sometimes spyhops
- often breaches, especially when young, and may do complete back somersaults
- may lobtail when feeding
- associates with Bottlenose Dolphins and, to a lesser extent, with Finless Porpoises and Long-snouted Spinner Dolphins

Distribution

- shallow coastal waters of the Indian and western Pacific Oceans
- distribution is poorly known; uncertain whether it is continuous from southern Africa all the way to Australia
- not yet recorded in the Philippines, though seems likely to occur there
- lives mainly in tropical and subtropical waters
- rarely found more than a few miles from shore, preferring coasts with mangrove swamps, lagoons, and estuaries, as well as areas with reefs, sandbanks, and mudbanks
- sometimes enters rivers, though rarely more than a few miles upstream and usually within the tidal range
- prefers water less than 65 ft (20 m) deep and, found in the surf zone


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This page was created by:Candice Orca Mottet