Pygmy killer whale

The pygmy killer whale (Feresa attenuata) is a small, rarely seen cetacean of the oceanic dolphin family (Delphinidae). It derives its common name from sharing some physical characteristics with the killer whale. It is the smallest species that has "whale" in its common name. In fact, "killer" may be more apt in the case of the pygmy killer whale than its larger relative; when a number of pygmy killers were brought into captivity in Hawaii and South Africa, they were extremely aggressive—even killing other poolmates. A pod captured in Japan did not display such aggression.

Although it had been described by John Gray in 1874, the pygmy killer whale, until the early 1950s, was known only from two skulls kept at the British Museum. In 1954, Japanese cetologist Munesato Yamada published accounts of a "rare porpoise" discovered in 1952 by whale hunters working from Honshū. He wrote that the individuals he examined had skulls matching those in the museum and that the body had features similar to the killer whale, and proposed the common name lesser (or pygmy) killer whale. Despite its name and features, the pygmy killer whale is of a different genus to the killer whale.