After that, the seal family tree diverges into the Pinnipedia branch. These are all semiaquatic mammals that hunt for their prey in the water. They have flippers rather than paws and their relatively large, torpedo-shaped torsos are perfectly suited for aquatic life. All Pinniped families have in common that they have thick layers of blubber and very short tails.

The three pinniped families are: Phocidae (true seals), Otariidae (eared seals) and Odobenidae (walruses).

Pinnipeds are considered to be semiaquatic, which means they spend part of their lives on land and part of their lives in the sea. Their two living spaces – the land and the sea – are used in different ways. The water is where they spend most of their time. There they find fish, crustaceans, molluscs and other tasty treats. The land is where they rest, warm up, mate, and birth their pups.

To live such a substantial portion of your life in the water, you need more than just flippers and a hydrodynamic body. Other adaptations allow pinnipeds to not only swim faster, but also dive deeper and longer than most other mammals. The only mammals better suited to life in the water are the cetaceans – or whales – which do not leave the water at all.