There are three families of pinnipeds.
True seals
The most remarkable of true seals are their typical ears. They do not have ear flaps, but tiny ear holes instead located at the side of the head. These family of pinnipeds has a distinct small tail. The seals' front flippers are short and blunt and covered with hair. They have clawlike nails on digits. Like the front flippers the true seals' hind flippers are covered with hair. The hind flippers are short and look like paddles with webbed digits with nails. True seals cannot turn their hind fippers forward, like eared seals can do for locomotion on land. True seals move along land hoppingon their belly. They do not use their hind flippers and the front flippers are only used to keep balance. These seals use their hind flippers only to push them selves on the water.
True seals live in all seas and oceans.
A subfamily of the true seals are the ringed seals. Because of the remarkable rings around their neck and body, these seals are called so.
A second subfamily of true seals are the bearded seals. Their long vibrissa, due to their helical shape, from a distance look like a beard.
The third subfamily of true seals is formed by the harbour seals. It is probably the most wide-ranging subfamily of seals consisting of 5 species. The Eastern and Western Atlantic Harbour seals, the Pacific harbour seal and the Insular seal all inhabit the Northern Atlantic and Pacific coast lines. The fifth species, the ungava seal, lives in The freshwater Seal Lake in Quebec (Canada). The most well known harbour seal might be the Pacific harbour seal which can be seen along the west coasts of the USA. But also the Eastern Atlantic harbour seal is a very common seal, which lives in the wastern part of the Atlantic Ocean from Spitsbergen (Norway) to Bretagne (France).
Eared seals
In contrast to true seals eared seals have small, slim external ear flaps located at the side of the head. Generally they have a pointed snout. They have a small tail. All flippers are hairless. The eared seals' front flippers are long and winglike. They have no noticeable nails. Eared seals use their front flippers to push themselves on the water. The front flippers are usually used for locomotion on land too, but these seals also can walk on their front and hind flippers. The hind flippers are large and look like paddles. They have webbed digits. On the three middle digits they have nails. The hind flippers can be turned forward for locomotion on land.
Eared seals live in the southern seas and the Pacific Ocean. In the northern Atlantic Ocean they do not occur.
Eared seals roughly can be devided into two groups: Fur Seals and Sea Lions
The California Sea Lion is often used for scientific investigation onto memory, understanding and intelligence of animals. This sea lion has a very well developed ability to learn.
Fur seals owe their name to their thick coat of fur.
Walruses
Walruses are the smallest family of pinnipeds. Therefore, they are the biggest pinnipeds. Both male and female walruses have tusks in their upper jaw. They have a small tail, but it is hide in a skin creases. Their front flippers are large. Like eared seals walruses can turn their hind flippers forward for locomotion on land. They can walk quite well on their four flippers. Like true seals these animals do not have ear flaps. They hear through tiny ear holes located at the sides of the head. These pretty gregarious animals can be seen in groups up to hundreds of animals. Their are two groups of walruses. The Pacific Walrus and the Atlantic Walrus. The last one is slightly smaller than the first one.