Like the crabeater seals, leopard seals have unusual teeth for straining krill. They supplement their diet of krill by eating seal pups and penguins. Leopard seals have very individual tastes. Some remain near penguin colonies and eat the penguins they catch there while others prefer to eat crabeater seal pups. Other leopard seals prefer a sub-antarctic menu and migrate north to Heard Island to feed on penguin and seal pups there.
Elephant seals are big and cumbersome on land, but they are superb swimmers and divers.
Biologists have recorded them diving up to 2km deep and holding their breath under water for up to 2 hours. Elephant seals are able to accomplish these amazing diving feats because they have evolved some special adaptations, by which they conserve energy very economically. They have a torpedo shape, which accounts for their prowess in swimming and diving. They have an enormous volume of blood in which to store oxygen and they use this oxygen very efficiently. Elephant seals even have extra spaces called sinuses in their abdomens to store all their extra blood.