Mammals breathe air through lungs, bear live young, produce milk for their young, are warm-blooded, and have hair or fur.
Marine mammals are mammals that have adapted, or adjusted, to life in the ocean.
Marine mammals have all the characteristics of mammals, yet they are distinctive in their appearance and survival strategies. Learning to identify marine mammals is made easier by learning their scientific classification. Sea lions and fur seals have visible external ears and can walk on all four flippers by rotating their rear flippers forward. They are more mobile on land than true seals, and are often seen in circuses and oceanaria. Their swimming power comes from their large front flippers.