These are black, stocky animals and the only large whales that lack a dorsal fin. With short, paddle-shaped flippers and prominent patches of callosities (raised skin patches) on their broad heads, together with their slow moving behaviour make them very easy to identify. Many individuals have large white patches, mostly on the ventral surface and during breaching these markings regularly lead to observers identifying it as a killer whale. About 4% of calves are born almost completely white, but will change to an overall grey colour within the first year. Both these white markings, as well as the callosities, which are markedly different on all individuals, are very useful in identification.
Callosities are rough, raised skin patches, essentially precisely where hair would grow on a humans face – above the eyes, on the chin and above the upper lip. They are inhabited by parasites, which cling to and feed off the discarded or dead skin. The function of callosities remains a matter of speculation. Whereas all toothed whales have a single blowhole (nostril), baleen whales have double blowholes, and southern right whales are unique with their typical V-shaped blow (condensation on exhaling).
Southern right whales are specialized filter feeders, using their finely meshed, long baleen plates to trap their prey. They do not undertake the spectacular feeding display of humpback whales but rather use a steady open-mouthed movement, nor do they feed on such a large variety of organisms.
Right whales almost exclusively feed on copepods or krill, which are only present in large accumulations in the cold sub arctic and sub Antarctic waters, and a few cold-water upwellings on the edge of continental shelves.