Finless Porpoise

Appearance: Small, streamlined body with a dorsal ridge ommencing just behind the blowhole and extending to the beginning of the tailstock. This feature is covered in circular wart-like tubercles or bumps. It is the only species of porpoise to have a bulbous melon. There is no prominent beak, giving the animal a blunt-headed appearance.

The mouth is small and slightly upward-curving. Unfused neck vertebrae allow for unrestricted head movement. There is a slight depression behind the single blowhole.

Key Characteristicsfin-whale

  • Streamlined body
  • No dorsal fin
  • Ridge from blowhole to flukes
  • Small bumps along rear dorsal ridge
  • Small, curving mouth
  • Blue grey in colour
  • Active swimmer
  • Rolls when surfacing to breathe
  • Shy and difficult to approach

Dorsal Fin: none

Flukes: concave trailing edges.

Flippers: long and pointed, with a narrow base.

Teeth: spatulate. Upper jaw 26-44, lower jaw same.

Colouration: pale blue-grey with a lighter belly, chin and ‘lips’. The skin darkens to black after death, this is the origin of the old common name for this species, finless black porpoises. Newborn calves are mostly black with grey round the dorsal ridge area, becoming fully grey in four to six months.

About half of all finless porpoises have pink eyes.

Behaviour: The finless porpoise is known to be shy and difficult to approach. It is a very active swimmer, typically swimming just beneath the surface with sudden, darting movements and rolling to one side when surfacing to breathe. This movement disturbs very little water on the surface, so finless porpoises often go unnoticed when rising to breathe. This movement disturbs very little water on the surface, so finless porpoises often go unnoticed when rising to breathe. Surfacing generally lasts about minute as the animal takes 3-4 quick, successive breathes, then quickly submerges, remaining under water for less than a minute. However, a finless porpoise will often surface a great distance from the point at which it dived beneath the surface.

Although this animal is shy of boats, it is known to spyhop and perform tailstands, but is rarely seen breaching. There are reports of mothers carrying their calves on their backs.

Group size: 1-12

Diet: small fish, cephalopods, and crustaceans. Finless porpoises also apparently ingest some plant material, including leaves.

Distribution: warm shallow coastal, estuarine and riverine areas with soft or sandy bottoms.

Given the species’ wide distribution off Southern India, it is most likely present north of Mannar from Adam’s Bridge to Palk Bay, Palk Strait and around the islands off Jaffna.

Sightings: Sri Lanka – possible, unconfirmed sightings. India – occasional