Then they return to the surface of the water to eat the fish. I don't know how they catch squid. The ancestors of the seal were land animals, and it took thousands of years to adapt to the land and waters of the Arctic. They remained mammals, and when seals swim in icy waters they must be sure that there are many holes in the ice so they can breathe. They have good senses of hearing and sight, but they are not very good at smelling, probably because the cold limits the scents around them and not much smelling is therefore needed.
All seals are warm blooded.
This helps keep them warm, but because it is so cold in the Arctic they also have an undercoat and overcoat of fur as well as one to six inch layer of blubber under their skin. Seals are all good swimmers, but eared seals can move around on land better than true seals with their larger front flippers. The Northern fur seal is the only breed which can sleep in the water, as its yearly migration keeps it far from land.