The orca (Orcinus orca), or killer whale, is a toothed whale and the largest member of the oceanic dolphin family. It is the only extant species in the genus Orcinus and is recognizable by its black-and-white patterned body. A cosmopolitan species, it is found in diverse marine environments, from Arctic to Antarctic regions to tropical seas.

Orcas are apex predators with a diverse diet. Individual populations often specialize in particular types of prey. This includes a variety of fish, sharks, rays, and marine mammals such as seals and other dolphins and whales. They are highly social; some populations are composed of highly stable matrilineal family groups (pods). Their sophisticated hunting techniques and vocal behaviors, often specific to a particular group and passed along from generation to generation, are considered to be manifestations of animal culture.

The International Union for Conservation of Nature assesses the orca's conservation status as data deficient because of the likelihood that two or more orca types are separate species. Some local populations are considered threatened or endangered due to prey depletion, habitat loss, pollution (by PCBs), capture for marine mammal parks,[6] and conflicts with human fisheries. In late 2005, the southern resident orcas were placed on the U.S. Endangered Species list.

Orcas are not usually a threat to humans, and no fatal attack has ever been documented in their natural habitat. There have been cases of captive orcas killing or injuring their handlers at marine theme parks.

Naming

Orcas, despite being dolphins, are commonly called 'killer whales' due to a mistranslation of the Spanish 'asesino de ballenas' (literally 'whale killer'), reflecting their historical predation on whales.[7] Since the 1960s, the use of "orca" instead of "killer whale" has steadily grown in common use.[8]

The genus name Orcinus means 'of the kingdom of the dead',[9] or 'belonging to Orcus'.[10] Ancient Romans originally used orca[11] (pl. orcae) for these animals, possibly borrowing Ancient Greek ὄρυξ (óryx), which referred (among other things) to a whale species, perhaps a narwhal.[12] As part of the family Delphinidae, the species is more closely related to other oceanic dolphins than to other whales.[13]

They are sometimes referred to as 'blackfish', a name also used for other whale species. 'Grampus' is a former name for the species, but is now seldom used. This meaning of 'grampus' should not be confused with the genus Grampus, whose only member is Risso's dolphin.[14]

Taxonomy

Orcinus citoniensis fossil, an extinct species of the same genus, Museo Capellini in Bologna

Modern orca skeleton, Naturalis, Leiden

Orcinus orca is the only recognized extant species in the genus Orcinus, and one of many animal species originally described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae.[15] Konrad Gessner wrote the first scientific description of an orca in his Piscium & aquatilium animantium natura of 1558, part of the larger Historia animalium, based on examination of a dead stranded animal in the Bay of Greifswald that had attracted a great deal of local interest.[16]

The orca is one of 35 species in the oceanic dolphin family, which first appeared about 11 million years ago.