Their red blood cells may, as an adaptation for diving, contain more haemoglobin than normal. These extra red blood cells make elephant seals' blood very thick. Elephant seal muscles are also used to store oxygen. Molecules of myoglobin, an oxygen-carrying molecule similar to haemoglobin are present in the muscles and colour the muscles black. When the elephant seal takes a breath it is like a fully-charge battery which can make oxygen last for up to two hours.
Elephant seals eat squid and fish and can navigate very accurately.
Australian scientists have tracked these seals using plastic ear tags. Elephant seals cruise the whole ocean and can swim enormous distances. Individuals spotted on Kerguelen Island, for example, have later been seen at Davis then Casey station in Antarctica. Fur seals Fur seals are the smallest seals and are closely related to dogs. They have teeth, whiskers and thick fur, similar to the coat of a dog.