Porpoises have a beakless upturned mouth and a slight
indentation at the location of the blowhole. Their flippers
are large, with a broad base and blunt tips.The dorsal
fin is set further back on this porpoise than on any
other small cetacean; a series of tubercles are found
on its leading edge.The tail stock thickens with age.
The body is dark-grey or black in colour, occasionally
appearing brown, and lightens to a pale grey underneath.
A few moments after death, the porpoise turns entirely
black. The largest specimen so far measured was 1.85m