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Leopard Seal

 
Britannica Concise Encyclopedia: leopard seal
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Species (Hydrurga leptonyx) of generally solitary earless seal (family Phocidae) found in Antarctic and sub-Antarctic regions. It is the only seal that feeds on penguins, young seals, and other warm-blooded prey. It is slender and has a long head and long three-cusped cheek teeth. Named for its black-spotted gray coat, it attains a maximum length and weight (greater in the female) of about 12 ft (3.5 m) and 840 lbs (380 kg). It has a reputation for ferocity but is not known to make unprovoked attacks on humans.

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Leopard Seal[1]
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Suborder: Pinnipedia
Family: Phocidae
Genus: Hydrurga
Gistel, 1848
Species: H. leptonyx
Binomial name
Hydrurga leptonyx
(Blainville, 1820)
Hydrurga leptonyx range map
Synonyms
  • homei (Lesson, 1828)
  • leptonyz (de Blainville, 1820)

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.[3] Orcas and large sharks are the only natural predators of leopard seals.[4]

Along with all of the other earless seals, it belongs to the family Phocidae, and is the only species in the genus Hydrurga.

Contents

The scientific name

The name Hydrurga means "water worker" and leptonyx is the Greek for "small clawed".

Description

A growling leopard seal

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.[5] The bulls are generally 2.5–3.2 m (8.2–10 ft) and weigh between 200 and 453.5 kg (440 and 1,000 lb), while cows are between 2.4 and 3.4 m (7.9 and 11 ft) in length and weigh between 225 and 591 kg (500 and 1,300 lb).[6]

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 (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.

Behaviour

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

A leopard seal feeding on a gentoo penguin

The leopard seal is the Antarctic's equivalent of the polar bear and is the top predator on the continent. It has canine teeth that are 2.5 cm (1 in).[7] 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.

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.[8]

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.[9] Examples of aggressive behavior, stalking and attacks have been documented,[10] 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 1914–1917 when the expedition were camping on the sea ice.[9] 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.[9][10]
  • 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.[9][10]

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.[10]

See also

Notes and References

  1. ^ Wozencraft, W. C. (16 November 2005). Wilson, D. E., and Reeder, D. M. (eds). ed. Mammal Species of the World (3rd edition ed.). Johns Hopkins University Press. ISBN 0-801-88221-4. http://www.bucknell.edu/msw3/browse.asp?id=14001042. 
  2. ^ Southwell, C. (2008). Hydrurga leptonyx. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 28 January 2009.
  3. ^ "Leopard Seal Description & Characteristics". The Antarctic Connection. http://www.antarcticconnection.com/antarctic/wildlife/seals/leopard.shtml. Retrieved 2007-12-10. 
  4. ^ http://animaldiversity.ummz.umich.edu/site/accounts/information/Hydrurga_leptonyx.html
  5. ^ Tunstall, T. "Hydrurga leptonyx". Animal Diversity Web. University of Michigan Museum of Zoology. http://animaldiversity.ummz.umich.edu/site/accounts/information/Hydrurga_leptonyx.html. Retrieved 2009-04-27. 
  6. ^ Nowak, Ronald M (2003). Walker's Marine Mammals of the World. Johns Hopkins University Press: Baltimore, MD. 
  7. ^ Kindersley, Dorling (2001,2005). Animal. New York City: DK Publishing. ISBN 0-7894-7764-5. 
  8. ^ Walker, T.R., Boyd, I.L., Mccafferty, D.J., Huin, N., Taylor, R.I., Reid, K. (1998) Seasonal occurrence and diet of leopard seals, Hydrurga leptonyx at Bird Island, South Georgia. Antarctic Science. 10(1): 75-81.
  9. ^ a b c d http://www.newscientist.com/article/dn3978-inquiry-into-fatal-leopard-seal-attack-begins.html
  10. ^ a b c d Owen, James (August 6, 2003). "Leopard Seal Kills Scientist in Antarctica". National Geographic Society. http://news.nationalgeographic.com/news/2003/08/0806_030806_sealkiller.html. Retrieved 2007-12-10. 

General References

  • 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

External links

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