Dolphin This term has often been misused in the US, mainly in the fishing industry, where all small cetaceans (dolphins and porpoises) are considered porpoises, while the fish "dorado" is called dolphin fish. In common usage the term 'whale' is used only for the larger cetacean species, while the smaller ones with a beaked or longer nose are considered 'dolphins'. The name 'dolphin' is used casually as a synonym for bottlenose dolphin, the most common and familiar species of dolphin. There are six species of dolphins commonly thought of as whales, collectively known as blackfish: the killer whale, the melon-headed whale,
Blue whale Naturae" of 1758, would have known this and may have intended the ironic double meaning. Herman Melville called this species "sulphur-bottom" in his novel "Moby-Dick" (1851) due to an orange-brown or yellow tinge on the underparts from diatom films on the skin. Other common names for the blue whale have included "Sibbald's rorqual" (after Sibbald, who first described the species), the "great blue whale" and the "great northern rorqual". These names have now fallen into disuse. The first known usage of the term "blue whale" was in Melville's "Moby-Dick", which only mentions it in passing and does not specifically attribute