Leopard seals
Description
Leopard Seals (Hydrurga leptonyx) are solitary animals that inhabit pack-ice surrounding the Antarctic continent. The leopard seal is easily identified: designed for speed, the body is slender and the foreflippers long. The head is large and the jaws open widely revealing exceptionally long canines and unusually complex sharply pointed molars. Like the crabeater seals, leopard seals have unusual teeth for straining krill.
Leopard Seal (Hydrurga leptonyx)
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Leopard seal
Photo: Christopher Clarke | |
Leopard Seal at Petersen Island
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Males (2.8 m; 320 kg) are generally slightly smaller than females (3.0 m; 370 kg). Large females may reach lengths in excess of 3.5 m and weigh over 500 kg.
Leopard seals may live for 26 years or more.
Diet
Leopard seals eat almost anything. Their favourite food would be penguins but seals, fish, squid and crustaceans are also consumed. Seals eaten include seal pups of crabeater, Weddell and fur seals. One animal, captured near Sydney, contained a full grown platypus.
The feeding behaviour of leopard seals is easily seen when their prey is penguin. Typically the seals chase or grab penguins in the water and thrash the captured bird back and forth until the skin peels away. The remaining carcass is then consumed.
Leopard seals have very individual tastes. Some remain near penguin colonies and eat the penguins they catch there while others prefer to eat crabeater seal pups. Other leopard seals prefer a subantarctic menu and migrate north to Heard Island to feed on penguin and seal pups there.
Breeding
Because leopard seals are solitary animals that live in the vasts of the Antarctic pack ice, little is known of their biology. Female leopard seals of six years or more give birth to a single pup on the sea-ice in November after a nine month gestation, and then return to the ocean to feed. The pup may weigh in excess of 30kg.
Abundance and distribution
Leopard seals are perhaps the greatest wanderers of the Antarctic seals with sightings in Tasmania and a most northern record at Heron Island. Heron Island is located at 23 degrees 27 minutes South - quite some distance from the Antarctic! Taronga Park Zoo has a captive animal.
They may occur year-round on some subantarctic islands including the Australian territory of Heard Island. In the winter months, young leopard seals from the south visit Macquarie Island.
The population may be as large as 222,000 individuals.
Threats
The only natural predator of leopard seals is the killer whale, though an indirect observation of a male elephant seal having killed a leopard seal while ashore at Heard Island has been reported (an uncommon occurrence no doubt).
The Australian Antarctic Division is interested in the factors that drive the cyclic nature of the occurrence of leopard seals at Macquarie Island and further to Tasmania. Studies of the movements of the seals within the pack-ice zone are also undertaken.
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