The smallest known species of whale is the dwarf sperm whale (Kogia sima). It is 2 to 2.7 m (6 ft 7 in to 8 ft 10 in) long and 136 to 272 kg (300 to 600 lb) in weight.
The dwarf sperm whale is smaller than smaller than most of dolphins. It swims in the Atlantic, Pacific and Indian Ocean, being one of three species in the sperm whale family. The dwarf sperm whale and pygmy sperm whale (Kogia breviceps) look very similar and it is difficult to distinguish between the two species at sea.