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Difference between revisions of "Weddell seal"
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[[File:Weddell seals-Diving.jpg|thumb|Weddell seals under ice]] | |||
The '''Weddell seal''', ''Leptonychotes weddellii'', is a relatively large and abundant true seal with a circumpolar distribution surrounding [[Antarctica]]. Weddell seals have the most southerly distribution of any mammal, with a habitat that extends as far south as McMurdo Sound (at 77°S). Because of its abundance, relative accessibility, and ease of approach by humans, it is the best-studied of the Antarctic seals. An estimated 800,000 individuals remain today. | The '''Weddell seal''', ''Leptonychotes weddellii'', is a relatively large and abundant true seal with a circumpolar distribution surrounding [[Antarctica]]. Weddell seals have the most southerly distribution of any mammal, with a habitat that extends as far south as McMurdo Sound (at 77°S). Because of its abundance, relative accessibility, and ease of approach by humans, it is the best-studied of the Antarctic seals. An estimated 800,000 individuals remain today. | ||
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The Weddell seal was discovered and named in the 1820s during expeditions led by James Weddell, the British sealing captain, to the parts of the [[Southern Ocean]] now known as the Weddell Sea. However, it is found in relatively uniform densities around the entire Antarctic continent. | The Weddell seal was discovered and named in the 1820s during expeditions led by James Weddell, the British sealing captain, to the parts of the [[Southern Ocean]] now known as the Weddell Sea. However, it is found in relatively uniform densities around the entire Antarctic continent. | ||
==Taxonomy and evolution== | ==Taxonomy and evolution== | ||
[[File:Weddell Seal Pup.jpg|400px|thumb|''Weddell Seal Pup'' by artist [[Christine Wood]]]] | |||
The Weddell seal shares a common recent ancestor with the other Antarctic seals, which are together known as the ''lobodontine'' seals. These include the [[crabeater seal]] and the [[leopard seal]]. These species share teeth adaptations including lobes and cusps useful for straining smaller prey items out of the water. The ancestral Lobodontini likely diverged from its sister clade, the Mirounga (elephant seals) in the late Miocene to early Pliocene, when they migrated southward and diversified rapidly to form four distinct genera in relative isolation around Antarctica. | The Weddell seal shares a common recent ancestor with the other Antarctic seals, which are together known as the ''lobodontine'' seals. These include the [[crabeater seal]] and the [[leopard seal]]. These species share teeth adaptations including lobes and cusps useful for straining smaller prey items out of the water. The ancestral Lobodontini likely diverged from its sister clade, the Mirounga (elephant seals) in the late Miocene to early Pliocene, when they migrated southward and diversified rapidly to form four distinct genera in relative isolation around Antarctica. | ||
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==Behavior and breeding== | ==Behavior and breeding== | ||
[[File:Weddell-seal-Baby.jpg|thumb|Baby Weddell seal]] | |||
Weddell seals gather in small groups around cracks and holes in the [[ice]]. These animals can also be found in large groups on ice attached to the continent. In the winter, they stay in the water to avoid blizzards, with only their heads poking through breathing holes in the ice. These seals are often observed lying on their sides, when on land. They are very docile and placid animals and can be approached easily. | Weddell seals gather in small groups around cracks and holes in the [[ice]]. These animals can also be found in large groups on ice attached to the continent. In the winter, they stay in the water to avoid blizzards, with only their heads poking through breathing holes in the ice. These seals are often observed lying on their sides, when on land. They are very docile and placid animals and can be approached easily. | ||
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==Diet and predation== | ==Diet and predation== | ||
Weddell seals eat an array of fish, [[Antarctic krill|krill]], squid, bottom-feeding prawns, cephalopods and crustaceans. A sedentary adult eats around 10 kg (22 lb) a day, while an active adult eats over 50 kg (110 lb) a day. | [[File:Seal-&-toothfish-Jessica-Meir N.jpg|thumb|Weddell seal eating an Antarctic toothfist]] | ||
Weddell seals eat an array of fish, including the [[Antarctic silverfish]] and the [[Antarctic toothfish]], as well as [[Antarctic krill|krill]], [[glacial squid|squid]], bottom-feeding prawns, cephalopods and crustaceans. A sedentary adult eats around 10 kg (22 lb) a day, while an active adult eats over 50 kg (110 lb) a day. | |||
Scientists believe Weddell seals rely mainly on eyesight to hunt for food when light is available. However, during the Antarctic winter darkness, when no light is available under the ice where the seals forage, they rely on other senses, primarily the sense of touch from their vibrissae or whiskers, which are not just hairs, but very complicated sense organs with more than 500 nerve endings that attach to the animal’s snout. The hairs allow the seals to detect the wake of swimming fish and use that to capture prey. | Scientists believe Weddell seals rely mainly on eyesight to hunt for food when light is available. However, during the Antarctic winter darkness, when no light is available under the [[ice]] where the seals forage, they rely on other senses, primarily the sense of touch from their vibrissae or whiskers, which are not just hairs, but very complicated sense organs with more than 500 nerve endings that attach to the animal’s snout. The hairs allow the seals to detect the wake of swimming fish and use that to capture prey. | ||
Weddell seals have no natural predators when on fast ice. At sea or on pack ice, they become prey for [[orca|killer whales]] and [[leopard | Weddell seals have no natural predators when on fast ice. At sea or on [[pack ice]], they become prey for [[orca|killer whales]] and [[leopard seal]]s, which prey primarily on juveniles and pups. The Weddell seal is protected by the [[Antarctic Treaty]] and the Convention for the Conservation of Antarctic Seals. | ||
[[Category:Seals]] | [[Category:Seals]] | ||
[[Category:Animals of Westarctica]] | [[Category:Animals of Westarctica]] | ||