Concept
The southern elephant seal (Mirounga leonina) is one of two species of elephant seals. It is the largest member of the clade Pinnipedia and the order Carnivora, as well as the largest extant marine mammal that is not a cetacean. It gets its name from its massive size and the large proboscis of the adult male, which is used to produce very loud roars, especially during the breeding season. A bull southern elephant seal is about 40% heavier than a male northern elephant seal (Mirounga angustirostris), twice as heavy as a male walrus (Odobenus rosmarus), and 6–7 times heavier than the largest living mostly-terrestrial carnivorans, the polar bear (Ursus maritimus) and the Kodiak bear (Ursus arctos middendorffi),. The southern elephant seal was one of the many species originally described by Swedish zoologist Carl Linnaeus in the landmark 1758 10th edition of his Systema Naturae, where it was given the binomial name of Phoca leonina. John Edward Gray established the genus Mirounga in 1827. In the nineteenth century the species was often called "bottle-nosed seal". The southern elephant seal is distinguished from the northern elephant seal (which does not overlap in range with this species) by its greater body mass and a shorter proboscis. The southern males also appear taller when fighting, due to their tendency to bend their backs more strongly than the northern species. This species may also exhibit the greatest sexual dimorphism of any mammal in terms of mass ratio, with males typically five to six times heavier than females. On average female southern elephant seals weigh and measure long, whereas bulls can range from and grow to in length. For comparison, among the northern elephant seal and the sperm whale (Physeter macrocephalus)—two other large marine mammals that are highly sexual dimorphic by size—males typically outweigh females by a factor of three to four. Southern elephant seal size also varies regionally. Studies have indicated elephant seals from South Georgia are around 30% heavier and 10% longer on average than those from Macquarie Island.
