Phocoenidae familia_authority = Gray (John Edward Gray), 1825 subdivision_ranks = Genera (Genus) subdivision = See text

Porpoises are small cetaceans of the family Phocoenidae; they are related to whales and dolphins. They are distinct from dolphins, although the word "porpoise" (pron-en?p?rp?s) has been used to refer to any small dolphin, especially by sailors and fishermen. The most obvious visible difference between the two groups is that porpoises have flattened, spade-shaped teeth distinct from the conical teeth of dolphins, and shorter beaks.

The name derives from French (French language) pourpois, originally from Medieval Latin porcopiscus (porcus pig + piscus fish).

Porpoises, divided into six species, live in all oceans, mostly near the shore. Freshwater populations of the Finless Porpoise also exist. Probably the best known species is the Harbour Porpoise, which can be found across the Northern Hemisphere. Like all toothed whales, porpoises are predators, using sounds (echolocation (animal echolocation) in sonar form) to locate prey and to coordinate with others. They hunt fish, squid, and crustaceans.