The Weddell Seal (Leptonychotes weddellii), is a true seal that occurs in large numbers and inhabits the circumpolar region of the southern hemisphere, including Antarctica. It is estimated that there are approximately 800,000 individuals today. These seals are said to live further south than any other animal. This pinniped is not thought to migrate, and any local movements are usually the result of changes in ice conditions.
The Weddell seal was named and discovered by a British sealing captain,James Weddell in the 1820s when he was on a sailing expedition within the Weddell Sea, also named after James Weddell. . It is the only species in the genus Leptonychotes.
A Weddell seal can grow 3 meters long and weigh between 400-600 kg.
Although female Weddell seals can be slightly larger, both male and female are generally about the same size. . However, the male seals have a thicker neck, and a broader head and muzzle than the females. Weddell seals have a smiling appearance because of their up turned mouth. Their face can be compared to a cat due to their short mouth line, and similarities with their nose and whiskers. .
The Weddell seal grows a thin fur coat around their whole body except for small areas around their flippers, the colour and pattern of this coat varies. As the fur ages, it often fades to a duller colour. . This coat moults around the beginning of summer. .
Adults are brown, lighter ventrally, and mottled with large darker and lighter patches, those on the belly being silvery white. Adult males usually bear scars, most of them around the genital region.
Young Weddell Seals have a gray pelage for the first 3 to 4 weeks; later they turn a darker color. The pups reach maturity at 3 years of age. The pups are born at around half the length of their mother, and weigh . They gain around a day, and by 67 weeks old they can weigh around . .
Depending on the latitude it inhabits, this marine mammal gives birth from early September through November, with those living at lower latitudes giving birth earlier. During the mating season the Weddell seals make noises that are loud enough to be felt through the ice.. Copulation has only been observed to occur underwater, where the female is often bitten on the neck by her partner. The seals are normally around 6-8yrs old when they first breed (but this can be much earlier for some females). . The Weddell seal is one of the only breeds of seals that can give birth to twin pups. . Birth of the pup only takes around 14 minutes. The pups take their first swim at around 12 weeks old. They can hold their breath for five minutes enabling them to be able to dive to lengths of . After 67 weeks they are weaned off their mother and can basically take care of themselves. .
Weddell seals eat an array of fish, krill, squid, bottom-feeding prawns, cephalopods, crustaceans and sometimes penguins. . A sedentary adult will need to eat around a day, while an active adult will eat over a day.
Weddell seals gather in small groups around cracks and holes in the ice. This animal can also be found in large groups on ice attached to the continent and can be easily approached by humans. In the winter months they stay in the water to avoid blizzards, with only their heads poking through breathing holes in the ice. . They are very docile and placid animals..
Weddell seals have no natural predators as they live on fast ice. If they are caught on pack ice they become prey for leopard seals and killer whales, this can often happen to pups and sub adults out exploring. . The Weddell Seal is protected by the Antarctic Treaty and the Convention for the Conservation of Antarctic Seals.
The Weddell Seal is known for its very deep dives, which may reach some . It can also stay underwater for approximately 80 minutes. Such deep dives involve foraging sessions, as well as searching for cracks in the ice sheets that can lead to new breathing holes. The seal can remain submerged for such long periods of time because of high concentrations of myoglobin in their muscles.
The Weddell Seal has a shorter lifespan than most other pinnipeds. On average, the Weddell Seal lives for 20 years, compared to an average life expectancy of 40 years for most other seals. This is because the Weddell seals lives under the Antarctic sea ice in the winter adjacent to continental Antarctica where it must constantly maintain breathing holes by scraping the ice with its teeth. This has the effect of wearing down its teeth over time. Once a Weddell Seal's teeth have worn down to a certain level, the seal is unable to eat and eventually starves to death.
The Weddell Seal lives farther south than any other mammal, inhabiting the waters of McMurdo Sound, from the South Pole.
ADW: Leptonychotes weddellii
Adaptions of Diving MammalsAudio recording from Macaulay Library at Cornell Lab of Ornithology
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article Weddell Seal