These are the only porpoises to have a bulbous melon on their heads. As their name suggests, they are also unusual because they lack fins.

Subspecies
Possibly three (populations in the Yangtze river, around Japan and Korea, and others).

Life span
Unknown.

Statistics
Body length: 1.2-1.9m, Weight: 30-40kg.

Physical description
Finless porpoises have a rounded head without a beak. They lack a dorsal fin, a ridge takes its place, and they have a slender, streamlined shape. They are a pale grey colour, which darkens with age. Like all porpoises, they have spade-shaped teeth (as opposed to conical in dolphins).

Distribution
Finless porpoises inhabit coastal areas of the Pacific and Indian oceans, including some freshwater rivers.

Diet
They feed on krill and other crustaceans.

Behaviour
Finless porpoises gather in groups of typically 2-3 animals, and rarely up to groups of more than 20 animals. Females are said to carry their young on their backs.

Conservation status
Finless porpoises are classified as Data Deficient by the 2000 IUCN Red List, except for the Yangtze River subpopulation, which is listed as Endangered.