<P> The killer whale is one of 35 species in the oceanic dolphin family, which first appeared about 11 million years ago . The killer whale lineage probably branched off shortly thereafter . Although it has morphological similarities with the pygmy killer whale, the false killer whale and the pilot whales, a study of cytochrome b gene sequences by Richard LeDuc indicated that its closest extant relatives are the snubfin dolphins of the genus Orcaella . </P> <P> English - speaking scientists most often use the term "killer whale", although the term "orca" is increasingly used . Killer whale advocates point out it has a long heritage . Indeed, the genus name Orcinus means "of the kingdom of the dead", or "belonging to Orcus". Ancient Romans originally applied orca (plural orcae) to these animals, possibly borrowing it from the Greek ὄρυξ, which referred (among other things) to a whale species . Since the 1960s, "orca" has steadily grown in popularity; both names are now used . The term "orca" is euphemistically preferred by some to avoid the negative connotations of "killer", and because, being part of the family Delphinidae, the species is more closely related to other dolphins than to whales . </P> <P> According to some authors, the name killer whale is a mistranslation of the 18th century Spanish name asesina - ballenas which means literally whale killer . Basque whalers would have given it such name after observing pods of orcas hunting baleen whales . </P> <P> 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 . </P>

Where does the name killer whale come from