The Leopard Seal (Hydrurga leptonyx), belongs to the seal family Phocidae. It is the only species in its genus. Leopard Seals are the second largest species of seal in the Antarctic (after Southern Elephant Seals), and are near the top of the Antarctic food chain. Orcas are the only natural predators of Leopard Seals. They can live twenty-six years, possibly more.
Leopard seals are large and muscular, with dark grey backs and light grey stomachs. Their throats are whitish with the black spots that give the seals their common name. Females are generally larger than the males. The bulls are usually about 9.2 feet long and weigh up to 705 pounds. Cows are much larger weighing up to 815 pounds. Very large females can reach over 11 feet in length and weigh as much as 885 pounds.
Although they are true seals and swim with their hind limbs, they have powerful highly developed forelimbs, giving them a maneuverability similar to sea lions and fur seals – a classic example of convergent evolution. Like these eared seals, Leopard seals are shallow water hunters, and do not dive deep like the other seals of the Antarctic. Leopard seals have unusually loose jaws that can open more than 160 degrees allowing them to bite larger prey.
Like most carnivores, their front teeth are sharp, but their molars lock together in a way that allows them to sieve krill from the water, similar to crab eater seals. Their senses of eyesight and smell are highly developed. These senses, coupled with streamlined bodies that enable the seals to move swiftly through the water, ensure that they are formidable predators.