Southern elephant seal

Description

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 carnivoran, the polar bear (Ursus maritimus) and the Kodiak bear (Ursus arctos middendorffi), 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 400 to 900 kg (880 to 1,980 lb) and measure 2.6 to 3 m (8.5 to 9.8 ft) long, whereas bulls can range from 2,200 to 4,000 kg (4,900 to 8,800 lb) and grow to 4.2 to 5.8 m (14 to 19 ft) 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. The record-sized bull, shot in Possession Bay, South Georgia, on 28 February 1913, measured 6.85 m (22.5 ft) long and was estimated to weigh 5,000 kg (11,000 lb), although it was only partially weighed piecemeal. The maximum size of a female is 1,000 kg (2,200 lb) and 3.7 m (12 ft). A southern elephant seal's eyes are large, round, and black. The width of the eyes, and a high concentration of low-light pigments, suggest sight plays an important role in the capture of prey. Like all seals, elephant seals have hind limbs whose ends form the tail and tail fin.