【明報專訊】California sea lions belong to a group called pinnipeds (鰭足類). There are three families of pinnipeds: seals (海豹), sea lions (海獅) and walruses (海象). Pinnipeds are mammals, just like humans. They nurse their babies with milk. Sea lions are sometimes mistaken for seals. However, there's an easy trick to tell their difference. Look at the ears — sea lions have ear flaps (外耳殼) on the sides of their heads while seals only have tiny ear openings.