aquatic mammal, any of the small toothed whales
of the family Delphinidae, numbering more than 50 species. These include the true, or beaked, dolphins, the killer whale
, the pilot whale, and 12 freshwater species found in rivers of South America and S and E Asia. Most species are highly gregarious. The name dolphin,
meaning "beaked," is also applied to a species of fish (see dolphin
, fish). In the United States dolphins are often mistakenly called porpoises, a name correctly applied to small, blunt-nosed whales of another family. Until recently dolphins formed the basis of a widespread fishing industry; only the Japanese continue to hunt them for food on a large scale. They are accidentally caught and killed in large numbers in tuna seining operations.
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