Well, folks, we've come to the end of the series on pinnipeds. This has been a really fun one, and I hope that you've all found it to be informative as well. I just added everything up, and so far I've completed five series, with a total of 167 entries on distinct species (including this one). I'll post the pinniped round-up tomorrow.
The Weddell Seal (Leptonychotes weddellii) is one of the most well-known of the Antarctic seals because it has a wide range and large population, making it both accessible to researchers and easy to find. They can be found as far south as the 77th parallel, making it the southernmost distributed seal of all the pinnipeds found in the Antarctic. The Weddell Seal is named after James Weddell, a British seal hunter who led expeditions to the Southern Ocean during the 1820s.
Adult Weddell Seals are fairly large, with adult females typically growing larger than males. They can reach 11.5 feet (3.5 meters) in body length and weigh up to 1,322 pounds (600 kg). Males can be as long as females, but average about 9.5 feet (2.9 meters) and weigh around 1,100 pounds (500 kg). Males also have thicker shoulders and necks than females. The coats of Weddell Seals vary in color depending on age, with adults having more of a brown coat, while juveniles are gray.
The diet of Weddell Seals varies on how deep the animal wants to dive. They'll feed primarily on krill, squid, fish, and bottom-dwelling creatures like crabs, cephalopods and prawns. Occasionally they will take penguins or juvenile seals of other species. Weddell Seals are expert divers, though, and are negatively buoyant up to 164 feet (50 meters), which allows them to dive without expending much energy. They can stay underwater for up to 80 minutes. They're able to do this through a variety of means, including having more red blood cells relative to animals of similar body size, postponing build-ups of lactic acid entering the bloodstream until after the seal has surfaced, and the high amounts of myoglobin in their muscles.
Breeding and pupping season for Weddell Seals depends on the specific latitude where the seals reside, but generally it occurs between September and November. Unlike many other pinnipeds, Weddell Seals sometimes give birth to two pups, instead of just one. The pups their milestones early, completing their first swim within two weeks after being born, and starting to hunt completely on their own after being weaned at seven weeks. Weddell Seals typically gather in smallish groups around breathing holes in the ice, which is how they avoid being affected by harsh Antarctic blizzards. They stay in the water, taking turns to use the breathing holes.
It's estimated that the population of Weddell Seals is currently around 800,000, and isn't considered to be threatened. It doesn't mind being approached by humans, and is protected by the Convention for the Conservation of Antarctic Seals and the Antarctic Treaty. There are no large land predators in Antarctica, and only juvenile Weddell Seals are typically preyed upon by orcas and Leopard Seals. All in all, the Weddell Seal is in good shape, though climate change may put strain on the population through the reduction of pack ice.
Source for all images in this post.