There are very few marine mammals that live in the Antarctic but seals and sea lions are the more common ones
The seals fall into two groups: one group is the true (earless) seals and the other is the fur seals which have small flaps over their ears.
Antarctica has six types of seal. They are the Ross, Crabeater, Weddell, Fur, Elephant and Leopard seals. The largest are the elephant seals (up to 4000kg) and the smallest the fur seals (up to 150kg).
Leopard, Ross, Weddell and crabeater seals breed on the ice with the Weddell and Crabeater seals forming large colonies.
Fur seals and southern elephant seals are both found further north and form colonies on beaches.
Seals eat fish, squid or krill. The leopard seal also eats penguins and other seals. Seals can dive to more than 600 metres in their daily search of food and have specially adapted eyes for underwater vision in low light levels. Seals catch most of their prey under water, but also spend time on land or ice floes for breeding and raising their young. They often just lay about.
What protects them from the harsh environment is a thick layer of fat called blubber under their skin as well as fur for extra insulation on land. They have no fear of humans since they have no land predators and this has worked against them in the past with sealers and early explorers killing them for their oil and for meat.
Crabeater, Ross and leopard seals breed in different locations each breeding season making them difficult for researchers to find. Transceivers placed on the seals as well as satellite imagery and other new techniques are making the task of tracking them more easy as time goes on.