FASTFACTS

AREA COVERED:

5,000 miles round-trip.

HABITAT:

Sub-Antarctic islands of the south Atlantic, Pacific and Indian oceans.

PREDATORS:

killer whales, large sharks and leopard seals.

INDIVIDUAL HERD POPULATION:

Approximately 600,000.

ELEPHANT SEAL IN-DEPTH

More from NationalGeographic.com

SOUTHERN ELEPHANT SEAL (Mirounga leonine)

The southern elephant seal, whose numbers have declined dramatically over the past 40 years, shares a genus with the northern elephant seal, Mirounga angustirostris, which is smaller but similar in anatomy and behavior. The species eats mostly squid, but also fish. In turn, it is hunted by by killer whales, large sharks and leopard seals, who prey mostly upon pups and juveniles. In the 19th century, they also were heavily hunted by humans for their oil, which could be used for fuel. Southern elephant seals are astonishing divers. They can descend to depths of nearly 5,000 feet, and remain submerged for up to two hours at a time. Although they are fast and powerful in the water, southern elephant seals are clumsy on land, because they have difficulty lifting their huge bodies off the ground as they haul themselves on and off the beach.

Southern elephant seals generally must swim enormous distances from their home islands in the southern oceans to the edge of Antarctica twice a year, once after breeding and once after moulting, in order to hunt for food in the brutally cold waters where squid are most plentiful. Fortunately, elephant seals' streamlined, buoyant bodies make them efficient enough swimmers to cover 45 to 50 miles in a single day, and their ample stores of body fat are enough to fuel them for the arduous trip. Males hunt on the continental shelf, while females look for food further out within the pack ice, or near the Antarctic Polar Frontal Zone.

Southern elephant seals serve a role in the ecosystem as a source of food for other predators. They also are hosts for parasites, such as cestoda, acanthocephalans, and the louse Lepidophthirus macrorhini.