Leopard Seal
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| Hydrurga leptonyx (Blainville, 1820) |
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 Hydrurga leptonyx range map
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The Leopard Seal (Hydrurga leptonyx) is the second largest species of seal in the Antarctic (after the Southern Elephant Seal), and is near the top of the Antarctic food chain. 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.[3] Orcas 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.
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[edit] Physical 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 larger than the males. The bulls are generally 2.5 m (8.2 ft) to 3.2 m (10.5 ft) and weigh between 200 kg (441 lb) and 455 kg (1,003 lb), while cows are between 2.4 meters (7.9 feet) and 3.4 meters (11.2 feet) in length and weigh between 225 kg (496 lb) and 591 kg (1,303 lb). [4]
Compared to most phocids, the Leopard Seal is highly evolved for its role as keystone predator. Although it is a true seal and swim with its hind limbs, it has powerful and highly developed forelimbs similar to sea lions, giving it a maneuverability similar to otariids such as sea lions and fur seals, 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 (the Weddell Seal, the Ross Seal and the two species of elephant seals) 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. Its senses of eyesight and smell are highly developed. These senses, coupled with a streamlined body that enable the seal to move swiftly through the water, ensures that it is a formidable predator.
[edit] 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 their 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.
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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, the female gives birth to a single pup during the Antarctic summer. She protects the pup until it is able to fend for itself.
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.
[edit] Feeding
The Leopard Seal has canine teeth that are 1 in (2.54 cm).[5] It feeds on a wide variety of creatures: smaller seals probably eat mostly krill, but also squid and fish. Larger Leopard Seals probably switch to feed on King and Emperor Penguins, and, less frequently, other seals such as the Crabeater Seal.
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. This is very similar to how a crocodile tears its prey up as well.
[edit] Human attacks
In 2003, a Leopard Seal dragged a snorkeling biologist underwater to her death in what was identified as the first known human fatality from a Leopard Seal.[6] However, numerous examples of aggressive behavior, stalking, and attacks on humans had been previously documented.[6] The Leopard Seal has 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. The Leopard Seal has also been known to snap at people's feet through holes in the ice.
[edit] See also
[edit] References
- ^ Wozencraft, W. C. (16 November 2005). in Wilson, D. E., and Reeder, D. M. (eds): Mammal Species of the World, 3rd edition, Johns Hopkins University Press. ISBN 0-801-88221-4.
- ^ Seal Specialist Group (1996). Hydrurga leptonyx. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 12 May 2006.
- ^ Leopard Seal Description & Characteristics. The Antarctic Connection. Retrieved on 2007-12-10.
- ^ Nowak, Ronald M (2003). Walker's Marine Mammals of the World. Johns Hopkins University Press: Baltimore, MD.
- ^ Kindersley, Dorling (2001,2005). Animal. New York City: DK Publishing. ISBN 0-7894-7764-5.
- ^ a b Owen, James (August 6, 2003). Leopard Seal Kills Scientist in Antarctica. National Geographic Society. Retrieved on 2007-12-10.
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This article or section includes a list of references or external links, but its sources remain unclear because it lacks in-text citations. You can improve this article by introducing more precise citations. |
- Rogers, Tracey L. (2002). Leopard Seal. In William F. Perrin, Bernd Würsig & 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
[edit] External links
- Best Wildlife Photos of 2005 - "Underwater World" Winner: "Leopard Seal Pass"
- Antarctic Connection.com
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