The Southern Elephant Seal
Five species of true seal (the type without external ears) inhabit the Antarctic Regions feeding in the rich seas and breeding on the sub-antarctic islands or coastal regions. Of these, that largest (by far) is the Southern Elephant Seal. Other species include the Crabeater Seal, The Weddell Seal, the Ross Seal and the Leopard Seal.
An adult male elephant seal weighs about 2500 kg, although specimens in excess of 4000 kg have been recorded, making it the largest of any carniverous mammal. Females are significantly smaller, averaging 1000 kgs. The world population is estimated at about 700,000 which represents a small recovery from the large scale slaughter of elephant seals up until the middle of the 20th century for the purposes of obtaining oil by processing their blubber. Elephant seals spend most of their life at sea where they dive for food (fish and squid). They can dive to 2000 metres and stay submerged for up to 2 hours although a typical dive is 20 minutes and 1000 metres. Long dives are possible because of the seal's ability to lower its heart rate (even as low as a single beat per minute) and because their blood has a high proportion of haemoglobin and therefore retains a great deal of oxygen.
They come ashore to breed and raise pups on subantarctic islands where they often share territory with King Penguins. An alpha male will vigorously and agressively defend his territorial rights which include a harem of females (sometimes up to 50). This male is known as a 'beachmaster'. Females give birth usually between October and November. New born pups are black, about 1.25 metres in length and weigh about 45-50 kgs. They suckle from 3 milk orifices in their mothers' bellies. Seal milk is over 50% fat (compared to cow's milk at 4%) and the newborns grow at a fast rate, quadrupling in size after 3 weeks when they are fully weaned. At this time they moult their black skin which is replaced with a grey or brown coats.
In these pictures you can see elephant seals on the islands of Kerguelen and also at Puerto Madryn in Argentina.