• The common seal is born without a white embryonic coat, unlike other seals that are born on ice. In coastal forms, this coat disappears in the last days of pregnancy.

Embryo: Body color— The embryo's body is formed inside the uterus. By the end of the gestation period, it is covered with fine fur. Calf: Fur— Thick and soft fur helps to retain heat on land and in water. Calf: Number of whiskers— Sensitive whiskers help the calf to navigate in water after entering the sea. Adult: Body color— A streamlined body without external ears allows for fast swimming and diving. Adult: Number of flippers— Flippers are used for swimming and movement on land; the hind flippers help with steering. Adult: Number of teeth— Sharp teeth capture and hold slippery fish. Adult: Number of whiskers— Long sensitive vibrissae help to find fish even in darkness.