Right whale dolphins are cetaceans belonging to the genus Lissodelphis. It contains the northern right whale dolphin (Lissodelphis borealis) and the southern right whale dolphin (Lissodelphis peronii). These cetaceans are predominantly black, white beneath, and some of the few without a dorsal fin or ridge. They are smaller members of the delphinid family, oceanic dolphins, and very slender. Despite scientists being long acquainted with the species (the Northern species was identified by Titian Peale in 1848 and the Southern by Bernard Germain de la Cépède in 1804), little is known about them in terms of life history and behaviour.
The northern right whale dolphin is widely distributed in the temperate North Pacific in a band running from Kamchatka and mainland Japan in the west to British Columbia down to the Baja California Peninsula in the east. It is not known with certainty if they follow a migratory pattern. However, individuals have been observed close to the Californian shore following their main food source, squid, in winter and spring. Such sightings have not been recorded in summer. Otherwise these dolphins are pelagic. No global population estimates exist. There are an estimated 14,000 individuals close to the North American shoreline.
The southern right whale dolphin has a circumpolar distribution running from about 40° to 55°. They are sighted in the Tasman Sea in particular.