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Leopard Seal
The Leopard seal (Hydrurga leptonyx) is the second largest species of seal in the Antarctic (after the Southern Elephant Seal). It is most common in the southern hemisphere along the coast of Antarctica and on most sub-Antarctic islands, but can also be found on the coasts of southern Australia, Tasmania, South Africa, New Zealand, Lord Howe Island, Tierra del Fuego, the Cook Islands, and the Atlantic coast of South America. It can live twenty-six years, possibly more. Orcas and large sharks are the only natural predators of leopard seals.
Along with all of the other earless seals, it belongs to the family Phocidae, and is the only species in the genus Hydrurga.
The name Hydrurga means "water worker" and leptonyx is the Greek for "small clawed".
Description
The leopard seal is large and muscular, with a dark grey back and light grey on its stomach. Its throat is whitish with the black spots that give the seal its common name. Females are generally slightly larger than the males on average. The bulls are generally and weigh between , while cows are between in length and weigh between .
Compared to most phocids, the Leopard seal is highly evolved for its role as apex predator. Although it is a true seal and swims with its hind limbs, it has powerful and highly developed forelimbs similar to sea lions, giving it a similar maneuverability, a classic example of convergent evolution. Like these eared seals, the Leopard Seal is a shallow water hunter, and does not dive deep like the other seals of the Antarctic which can all dive to several hundred meters in search of squid. The leopard seal has an unusually loose jaw that can open more than 160 degrees allowing it to bite larger prey.
Like most carnivores, its front teeth are sharp, but its molars lock together in a way that allows them to sieve krill from the water, similar to the Crabeater seal.
Behavior
The leopard seal lives in the cold waters surrounding Antarctica. During the summer months, it hunts among the pack ice surrounding the continent, spending almost all of its time in the water. In the winter, it ranges north to the sub-Antarctic islands. Occasionally, individuals may be spotted on the southern coasts of South America, Australia, and New Zealand, and as far north as the Cook Islands. Juveniles are more often found in the north.
The leopard seal is a solitary creature and comes together in small groups only when it is time to mate. The female digs a hole in the ice and, after a nine month gestation, gives birth to a single pup during the Antarctic summer. She protects the pup until it is able to fend for itself.
They are very quiet except for some grunting and growling noises.
The leopard seal is bold, powerful and curious. In the water, there is a fine line between curiosity and predatory behavior, and it may 'play' with penguins that it does not intend to eat.
Diet
The leopard seal is the Antarctic's equivalent of the polar bear and is the top predator on the continent after the Orca whale. It has canine teeth that are . It feeds on a wide variety of creatures. Smaller seals probably eat mostly krill, but also squid and fish. Larger leopard seals probably switch from krill to more substantial prey, including King, Adelie Penguins, and Emperor Penguins, and less frequently, other seals such as the crabeater seal.
Around the sub-Antarctic Island of South Georgia the Antarctic fur seal (Arctocephalus gazella) is the main prey. Other prey includes penguins and fish. Antarctic krill (Euphausia superba), southern elephant seals (Mirounga leonina) and seabirds other than penguins have also been found in Leopard seal scats in small quantities.
When hunting penguins, the leopard seal patrols the waters near the edges of the ice, almost completely submerged, waiting for the birds to enter the ocean. It kills the swimming bird by grabbing the feet, then shaking the penguin vigorously and beating its body against the surface of the water repeatedly until the penguin is dead. Previous reports stating that the leopard seal skins its prey prior to feeding have been found to be incorrect. Lacking the teeth necessary to slice its prey into manageable pieces, it flails its prey from side to side in order to tear and rip it into smaller pieces.
Attacks on humans
Leopard seals are potentially highly dangerous towards humans, but attacks are rarely reported. Examples of aggressive behavior, stalking and attacks have been documented, notable incidents include:
A large leopard seal attacked Thomas Orde-Lees (1877 1958), a member of Sir Ernest Shackleton's Imperial Trans-Antarctic Expedition of 19141917 when the expedition were camping on the sea ice. A large "sea leopard" of approximately 12 feet long and 1,100 pounds chased Orde-Lees on the ice. He was only saved when another member of the expedition shot the animal.
In 1985, Scottish explorer Gareth Wood was bitten twice on the leg when a leopard seal tried to drag him off the ice and into the sea. His companions managed to save him by repeatedly kicking the animal in the head with the spiked crampons on their boots.
In 2003, a leopard seal dragged snorkeling biologist Kirsty Brown of the British Antarctic Survey underwater to her death, in what was identified as the first known human fatality from a leopard seal.
Leopard seals have previously shown a particular predilection for attacking the black, torpedo-shaped pontoons of rigid inflatable boats, necessitating that researchers equip their craft with special protective guards to prevent them from being punctured.
See also
Australian Marine Mammal Research Centre
General References
Rogers, Tracey L. (2002). Leopard Seal. In William F. Perrin, Bernd Wursig & J.G.M. Thewissen eds. Encyclopedia of Marine Mammals San Diego: Academic Press. 692-693.
National Geographic Magazine, November 2006 Leopard Seals
King, Judith E. (1975). Seals leopard on Lord Howe Island. Journal of Mammalogy, 56(1), pp. 251-252
External links
Best Wildlife Photos of 2005 - "Underwater World" Winner: "Leopard Seal Pass"
Antarctic Connection.com
Under-water close-up photos of leopard seals
HuffintongPost.com
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This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article Leopard Seal
