killer whale

killer whale, orca, or grampus, a large, rapacious marine mammal of the dolphin family. Historically considered one species, Orcinus orca, killer whales may be classified into several types, based on differences in appearance, prey preferences, and where they are found. Members of these groupings do not appear to interbreed, and some scientists believe, based in part on DNA evidence, that there are several species of killer whale. Killer whales are worldwide in distribution.

They are black above, with a sharply contrasting white oval patch around each eye; the belly is white with white markings projecting up along the animals' sides. They have a high, triangular dorsal fin midway between head and tail, and broad, paddle-shaped flippers. Male killer whales may reach a length of 30 ft (9 m) and females half that length.

Swift and ferocious animals, armed with more than four dozen sharp teeth, killer whales are the only cetacean (see whale) that feeds regularly on birds or mammals. Killer whales may eat seals, sea birds, and fish, and in packs they may even attack larger whales. The female gives birth to a single calf, up to 7 ft (2.1 m) long, following a gestation period of approximately one year. Females mature in 6 to 7 years, males in 12.

They are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Cetacea, family Delphinidae.

See more Encyclopedia articles on: Vertebrate Zoology