Seals are marine mammals, just like whales. They have many features which make them ideally suited to living in water. However, unlike whales, seals sometimes move onto dry land. Therefore, they are also suited to living on land. For example, they feed their pups and moult on land. Even though they can sleep at sea, seals actually rest better on land.
Moving through water at speed is harder than moving through air. That is why the seal’s body is streamlined, to minimise the resistance of water. Seals have a thick layer of fat on their bodies; this is called blubber. The blubber insulates the seal’s body, but also helps to make it even and smooth. Actually, it is only the seal’s flippers that disturb the streamlined shape. In addition, both the common seals and the grey seals lack outer ears, and the male seal’s penis is only extended visibly during mating.
When seals swim, they move their back flippers from side to side, while they use their front flippers to steer with. When they swim fast, they keep their front flippers close to the body. Both species of seal can swim up to 17 kilometres an hour over short distances, but normally from two to nine kilometres an hour.

Can you tell the difference?

It can be difficult to tell the difference between the common seal and the grey seal, even though the grey seal is somewhat larger than the common seal. However, there are some distinguishing features you can look for. The grey seal has a cone-shaped head, while the common seal’s head is rounder and its muzzle is short. You can also examine their nostrils. The nostrils of the grey seal are parallel, whereas the common seal’s nostrils look like a ‘V’. If you look at their teeth, you will notice that the grey seal’s back teeth are cone-shaped, while the common seal’s back teeth are serrated.