Leopard Seal
Encyclopedia
The leopard seal also referred to as the sea leopard, 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 shark
s are the only natural predators of leopard seals.
Along with all of the other earless seal
s, 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".
but usually less than half the weight.
Its front teeth are sharp like those of other carnivores, but its molars
lock together in a way that allows them to sieve krill
from the water, in the manner of the crabeater seal
.
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. During the mating season, males and females make acoustic calls to each other over distances, with at least the males having individual variability in their vocalising sequence patterns. After a nine-month gestation, the female digs a hole in the ice, and 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 penguin
s that it does not intend to eat.
The leopard seal is second only to the orca among Antarctica's top predators. Its canine teeth are 2.5 cm (0.984251968503937 in). 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
, rockhopper
, gentoo
and emperor penguin
s, 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 seal
(Mirounga leonina) pups 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 is helped in this endeavor by the penguins themselves, which nearly always push one of their own into the water ahead of themselves. 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 the leopard seal skins its prey before 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 to tear and rip it into smaller pieces.
All these seals descend from the superfamily Pinnipeds, which evolved from bear-like ancestors. They have diverged from other taxa in the order Carnivora.
The leopard seal has many analogous features similar to other species. One analogous feature is a forearm and five finger-like bones, which is the same structure found in humans and birds. However, in the leopard seal, these fingers are covered in a web of skin, which they use to propel themselves through the water. This is analogous to humans and birds, as humans use their fingers to manipulate tools, and birds use their fingers, covered in feathers, to fly.
The leopard seals share homologous features with its close relatives, the lobodontine seals. They all have dark fur on the tops of their bodies and lighter fur on their underbellies. Though the colours vary between these species of seals, the coloured fur serves the same function, which is for better camouflage against predators and as it stalks its prey.
Leopard seals have shown a particular predilection for attacking the black, torpedo-shaped pontoon
s of rigid inflatable boats, necessitating researchers to equip their craft with special protective guards to prevent them from being punctured.
Antarctic
The Antarctic is the region around the Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica and the ice shelves, waters and island territories in the Southern Ocean situated south of the Antarctic Convergence...
(after the southern elephant seal
Southern Elephant Seal
The Southern Elephant Seal is one of the two extant species of elephant seal. It is both the most massive pinniped and member of the order Carnivora living today...
). 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
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, Tasmania
Tasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
, South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
, New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, Lord Howe Island
Lord Howe Island
Lord Howe Island is an irregularly crescent-shaped volcanic remnant in the Tasman Sea between Australia and New Zealand, directly east of mainland Port Macquarie, and about from Norfolk Island. The island is about 11 km long and between 2.8 km and 0.6 km wide with an area of...
, Tierra del Fuego
Tierra del Fuego
Tierra del Fuego is an archipelago off the southernmost tip of the South American mainland, across the Strait of Magellan. The archipelago consists of a main island Isla Grande de Tierra del Fuego divided between Chile and Argentina with an area of , and a group of smaller islands including Cape...
, the Cook Islands
Cook Islands
The Cook Islands is a self-governing parliamentary democracy in the South Pacific Ocean in free association with New Zealand...
, and the Atlantic coast of South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. It can live twenty-six years, possibly more. Orcas and large shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....
s are the only natural predators of leopard seals.
Along with all of the other earless seal
Earless seal
The true seals or earless seals are one of the three main groups of mammals within the seal superfamily, Pinnipedia. All true seals are members of the family Phocidae . They are sometimes called crawling seals to distinguish them from the fur seals and sea lions of the family Otariidae...
s, it belongs to the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Phocidae, and is the only species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
in the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
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 overall length of this seal is 2.4-3.5 m (7.9-11.7 ft) and weight is from 200 to 600 kg (440.9 to 1,322.8 ). They are about the same length as the northern walrusWalrus
The walrus is a large flippered marine mammal with a discontinuous circumpolar distribution in the Arctic Ocean and sub-Arctic seas of the Northern Hemisphere. The walrus is the only living species in the Odobenidae family and Odobenus genus. It is subdivided into three subspecies: the Atlantic...
but usually less than half the weight.
Its front teeth are sharp like those of other carnivores, but its molars
Molar (tooth)
Molars are the rearmost and most complicated kind of tooth in most mammals. In many mammals they grind food; hence the Latin name mola, "millstone"....
lock together in a way that allows them to sieve krill
Antarctic krill
Antarctic krill, Euphausia superba, is a species of krill found in the Antarctic waters of the Southern Ocean. It is a shrimp-like crustacean that lives in large schools, called swarms, sometimes reaching densities of 10,000–30,000 individual animals per cubic metre...
from the water, in the manner of the crabeater seal
Crabeater Seal
The crabeater seal, Lobodon carcinophagus, is a true seal with a circumpolar distribution around the coast of Antarctica. They are medium to large-sized , relatively slender and pale-colored, found primarily on the free floating pack ice that extends seasonally out from the Antarctic coast, which...
.
Behaviour
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, and New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
, and as far north as the Cook Islands
Cook Islands
The Cook Islands is a self-governing parliamentary democracy in the South Pacific Ocean in free association with New Zealand...
. 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. During the mating season, males and females make acoustic calls to each other over distances, with at least the males having individual variability in their vocalising sequence patterns. After a nine-month gestation, the female digs a hole in the ice, and 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 penguin
Penguin
Penguins are a group of aquatic, flightless birds living almost exclusively in the southern hemisphere, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded dark and white plumage, and their wings have become flippers...
s that it does not intend to eat.
Diet
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
. Larger leopard seals probably switch from krill to more substantial prey, including king
King Penguin
The King Penguin is the second largest species of penguin at about , second only to the Emperor Penguin. There are two subspecies—A. p. patagonicus and A. p...
, adelie
Adelie Penguin
The Adélie Penguin, Pygoscelis adeliae, is a species of penguin common along the entire Antarctic coast. They are among the most southerly distributed of all seabirds, as are the Emperor Penguin, the South Polar Skua, the Wilson's Storm Petrel, the Snow Petrel, and the Antarctic Petrel...
, rockhopper
Rockhopper penguin
The rockhopper penguins are three closely related taxa of crested penguins that have been traditionally treated as a single species and are sometimes split into two or three species. Not all experts agree on the classification of these penguins...
, gentoo
Gentoo penguin
The Gentoo Penguin , Pygoscelis papua, is easily recognized by the wide white stripe extending like a bonnet across the top of its head and its bright orange-red bill. The gentoo penguin has pale whitish-pink webbed feet and a fairly long tail - the most prominent tail of all penguins. Chicks have...
and emperor penguin
Emperor Penguin
The Emperor Penguin is the tallest and heaviest of all living penguin species and is endemic to Antarctica. The male and female are similar in plumage and size, reaching in height and weighing anywhere from . The dorsal side and head are black and sharply delineated from the white belly,...
s, and less frequently, other seals such as the crabeater seal
Crabeater Seal
The crabeater seal, Lobodon carcinophagus, is a true seal with a circumpolar distribution around the coast of Antarctica. They are medium to large-sized , relatively slender and pale-colored, found primarily on the free floating pack ice that extends seasonally out from the Antarctic coast, which...
.
Around the sub-Antarctic island of South Georgia, the Antarctic fur seal
Antarctic Fur Seal
The Antarctic fur seal is one of eight seals in the genus Arctocephalus, and one of nine fur seals in the subfamily Arctocephalinae. As its name suggests, the Antarctic fur seal is distributed in Antarctic waters. Around 95% of the world population breeds at the Island of South Georgia...
(Arctocephalus gazella) is the main prey. Other prey includes penguins and fish. Antarctic krill
Antarctic krill
Antarctic krill, Euphausia superba, is a species of krill found in the Antarctic waters of the Southern Ocean. It is a shrimp-like crustacean that lives in large schools, called swarms, sometimes reaching densities of 10,000–30,000 individual animals per cubic metre...
(Euphausia superba), southern elephant seal
Southern Elephant Seal
The Southern Elephant Seal is one of the two extant species of elephant seal. It is both the most massive pinniped and member of the order Carnivora living today...
(Mirounga leonina) pups 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 is helped in this endeavor by the penguins themselves, which nearly always push one of their own into the water ahead of themselves. 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 the leopard seal skins its prey before 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 to tear and rip it into smaller pieces.
Phylogeny
The leopard seal is classified under the family Phocidae. Its closest relatives are the Ross seal, crabeater seal and the Weddell seal, which together are known as the lobodontine seals.All these seals descend from the superfamily Pinnipeds, which evolved from bear-like ancestors. They have diverged from other taxa in the order Carnivora.
The leopard seal has many analogous features similar to other species. One analogous feature is a forearm and five finger-like bones, which is the same structure found in humans and birds. However, in the leopard seal, these fingers are covered in a web of skin, which they use to propel themselves through the water. This is analogous to humans and birds, as humans use their fingers to manipulate tools, and birds use their fingers, covered in feathers, to fly.
The leopard seals share homologous features with its close relatives, the lobodontine seals. They all have dark fur on the tops of their bodies and lighter fur on their underbellies. Though the colours vary between these species of seals, the coloured fur serves the same function, which is for better camouflage against predators and as it stalks its prey.
Attacks on people
Leopard seals are potentially highly dangerous towards humans, but attacks are rarely reported. Examples of aggressive behaviour, stalking and attacks have been documented. Notable incidents include:- A large leopard seal attacked Thomas Orde-LeesThomas Orde-LeesThomas Orde-Lees was a member of Sir Ernest Shackleton's Imperial Trans-Antarctic Expedition of 1914–1917, a pioneer in the field of parachuting, and was one of the first non-Japanese-born men known to have climbed Mount Fuji during the winter.-Early life:Thomas Hans Orde-Lees was born on 23...
(1877–1958), a member of Sir Ernest ShackletonErnest ShackletonSir Ernest Henry Shackleton, CVO, OBE was a notable explorer from County Kildare, Ireland, who was one of the principal figures of the period known as the Heroic Age of Antarctic Exploration...
's Imperial Trans-Antarctic ExpeditionImperial Trans-Antarctic ExpeditionThe Imperial Trans-Antarctic Expedition , also known as the Endurance Expedition, is considered the last major expedition of the Heroic Age of Antarctic Exploration. Conceived by Sir Ernest Shackleton, the expedition was an attempt to make the first land crossing of the Antarctic continent...
of 1914–1917 when the expedition was camping on the sea ice. A large "sea leopard" of approximately 12 feet (3.7 m) long and 1100 pounds (499 kg) chased Orde-Lees on the ice. He was saved only 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 snorkelingSnorkelingSnorkeling is the practice of swimming on or through a body of water while equipped with a diving mask, a shaped tube called a snorkel, and usually swimfins. In cooler waters, a wetsuit may also be worn...
biologist Kirsty Brown of the British Antarctic SurveyBritish Antarctic SurveyThe British Antarctic Survey is the United Kingdom's national Antarctic operation and has an active role in Antarctic affairs. BAS is part of the Natural Environment Research Council and has over 400 staff. It operates five research stations, two ships and five aircraft in and around Antarctica....
nearly 200 feet (61 m) underwater to her death, in what was identified as the first known human fatality from a leopard seal.
Leopard seals have shown a particular predilection for attacking the black, torpedo-shaped pontoon
Pontoon (boat)
A pontoon is a flotation device with buoyancy sufficient to float itself as well as a heavy load. A pontoon boat is a flattish boat that relies on pontoons to float. Pontoons may be used on boats, rafts, barges, docks, floatplanes or seaplanes. Pontoons may support a platform, creating a raft. A...
s of rigid inflatable boats, necessitating researchers to equip their craft with special protective guards to prevent them from being punctured.
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
- Saundry, Peter. (2010) http://www.eoearth.org/wiki/Leopard_seal Leopard Seal]. Encyclopedia of Earth. Topic ed. C.Michael Hogan, ed. in chief Cutler Cleveland, NCSE, Washington DC