The porpoise family has only six members worldwide. It is, however, widely distributed. The smallest, the Vaquita Phocoena sinus, which is also known as the Cochito, is 1.5 m long, whilst the largest porpoises, Dall’s Porpoise Phocoenoides dalli and the Spectacled Porpoise Phocoena dioptrica, both grow up to 2.2 m.
Porpoises have small flippers and no beak. Except for the Finless Porpoise Neophocaena phocoenoides, the only species found around India, they all have a dorsal fin. The teeth of porpoises are flattened to cutting edges, unlike those of dolphins, which are conical, and enable these animals to slice their prey. The diet consists of squid and small fish in general.
The social groups formed by porpoises are usually smaller than those of dolphins. Porpoises are typically coastal animals.
The rare Vaquita, occurring only in the northern part of the Gulf of California, has a very restricted range. It is seriously threatened by gill net fisheries and is endangered. The Spectacled Porpoise, found in sub-Antarctic waters, is the least known porpoise. Severely threatened by gill net fisheries, it is one of the rarest and most endangered cetaceans.