PORPOISE

specifically, any of the small whales of the genera Phocoena, Phocoenoides, and Neomeris. In a broader sense the name is applied, especially in North America, to various other small whales more widely known as dolphins (see dolphin). Porpoises are distinguished externally from dolphins by their chubbier shape, usually smaller size (maximum length about two metres [seven feet]), and blunt, rather than beaklike, snout. Some authorities consider them a distinct family, Phocoenidae (or Phocaenidae); others as part of the dolphin family (Delphinidae). There are seven species of porpoises. Four, the common, or harbour, porpoises, are of the genus Phocoena. These animals are found in pairs or large groups along coasts and occasionally in rivers. Primarily fish eaters, they are gray or black above and white below. The species P. phocoena, the best known, is found throughout much of the northern hemisphere. It is shy, generally avoids boats, and rarely leaps above the water. It is hunted in some regions and in the Middle Ages was considered a royal delicacy. The other species in the genus, more restricted in distribution, are P. sinus of California and P. spinipinnis and P. dioptrica of South America. The Dall and True porpoises (Phocoenoides dalli and P. truei) are active, gregarious whales that often swim ahead of ships. They eat cephalopods (primarily squid) and fish and usually live in groups of 2 to 20. Both are black with a large white patch on each side. The Dall porpoise is found on both sides of the North Pacific. The True porpoise, considered by some authorities a subspecies, P. dalli truei, is found near Japan. The black finless porpoise, Neomeris (or Neophocoena) phocoenoides, is a small, slow porpoise of coastal waters and rivers along the Pacific and Indian oceans. It is black above and paler below; it has a rounded head and, unlike other porpoises, lacks a dorsal fin. Little is known of its habits. It lives alone or in small groups and eats crustaceans, fish, and squid.