The right whale dolphins, the Northern Right Whale Dolphin (Lissodelphis borealis) and the Southern Right Whale Dolphin (Lissodelphis peroni), are two of the easiest cetaceans to identify at sea. Both these oceanic dolphins are coloured black and white and have no dorsal fin. Despite scientists being long acquainted with the species (the Northern species was identified by Peale in 1848 and the Southern even earlier - Lacepede, 1804) surprisingly little is known about them in terms of life history and behaviour.

Both species have slender bodies, small, pointed flippers and a small fluke. Conspiciously neither species have a dorsal fin. The Northern Right Whale Dolphin is the only dolphin in the Pacific with this property. Similarly the Southern is the only finless dolphin in the southern hemisphere. The two species, apart from the geographical dislocation can be readily distinguished by the extent of the whiteness on the body. Both have white bellies. However the Southern species has more extensive white - including the flanks, flippers, beak and forehead.

Northern males are about 220cm long at sexual maturity. Females are 200cm. Both sexes become mature at about 10 years. New-born Right Whale Dolphins are about half the length of their parents. The Southern species are typically larger (up to 250cm) and heavier (up to 100kg compared with the Northern's maximum of 80-90kg). The dolphins live for about 40 years.