Bottlenose Dolphin

Appearance: Generally large, robust and bulky, particularly in comparison with the Indian Ocean bottlenose dolphin. It has a distinctive stubby beak, set off from the melon by a crease. This species is also darker than the Indian Ocean bottlenose dolphin, having a more bulky melon and a proportionately shorter, thicker rostrum.

Key Characteristicsbottlenose-dolphin

  • Dark grey colouring
  • Dark dorsal cape
  • Dark, prominent, falcate fin
  • Robust head and body
  • Distinct beak (bottlenose) with melon crease
  • Rounded forehead
  • Usually found alone or in small groups
  • Frequently bow rides
  • Highly active at surfac

Dorsal Fin: dark grey, high and falcate, located near the middle of the back.

Flippers: grey, moderately long, slender and pointed.

Flukes: grey board and curved, with a distinct median notch.

Teeth: upper jaw 42-52, lower 42-48

Colouration: complex, with considerable variation. The body may be slate grey, bluish or dun on the upper part, lightening on the sides, and pale greyish pink or almost white on the underside. In most lighting condition, however, the body appears as a featureless uniform grey. The dorsal cape is darker and there is a subtle dark stripe that runs from eye to flipper.

Behaviour: playful, inquisitive and sociable. Highly active at the surface; frequently bow-rides, lobtails, porpoises and breaches, often to a height of several meters. Common bottlenose dolphins are also known to play with fish, seaweed and marine debris.

The forehead is typically revealed when surfacing, but rarely the beak. Normal swimming speed is leisurely, between five and 7.5km/h, though these animals are capable of speeds up to 35km0h in short spurts.

Bottlenose dolphins exhibit complex social behavior. Although they are known to act aggressively toward one another as well as toward other cetaceans, they are not dangerous to humans. Inshore bottlenose dolphins seem to live in relatively open societies.

They are opportunistic feeders with a range of behavoiur that includes cooperative foraging, individual hunting, and feeding behind fishing trawlers. Inshore dives rarely last longer than 3-4 min, though offshore they may last as long as 8-10 min.

Group size: inshore 2-15; offshore up to five hundred.

Associates: pilot whales and rough-toothed dolphins, as well as sharks and sea turtle. Inshore groups associate with humpback dolphins.

Diet: fish and cephalopods

Dive Depth: 10-11m, max. >500 m, remaining submerged for up to 12 min.

Distribution: widely distributed all round Sri Lanka in coastal and continental-shelf waters. Population density appears to be higher near to shore. In some areas, common bottlenose may have limited home ranges; in others, they may be nomadic, accompanying pilot whales as they travel the deep ocean.

There may be too ‘ecotypes’ of the common bottlenose dolphin: a similar and lighter inshore form and a larger, slightly darker-coloured offshore form.

Sightings: all year round. Sri Lanka: common, abundant off south coast. Maldives: abundant