A shedded elephant seal with a sensor on its head. The sensor measures the animal's position, the depth of the dives, the water temperature and its salinity.
Marion Island, where a colony of southern elephant seals resides, is the bigger one of the two Prince Edward Islands in the southern Indian Ocean. It belongs to South Africa.
A lurking male elephant seal. The animals lay side by side on the beach and wait for their fur to shed. There is rarely space for everyone and if one seal moves, the others get stressed and start to bark.
Elephant seals and king penguin are sun bathing at Trypot Beach on Marion Island in the southern Indian Ocean.
After placing the sensor on the animal's head the biologists measure its body size. Elephant seals can withstand the cold waters due to their thick layer of blubber. It can be as thick as nearly 6 inches (15 centimeters) and accounts for one third of the animals weight of approximately three metric tons.