"Are dolphins fish or mammals? They certainly look like fish, but they have many things in common with other mammals. They need to breathe air because they do not have gills like many fish do. They give birth to live young. Some are even born with whiskers! In this volume, readers will dive into Earth's oceans to explore the animals live in them, paying particular attention to the differences between marine mammals, such as dolphins and whales, and the fish that they resemble. Filled with dazzling photographs and helpful diagrams, readers will come away with a solid understanding of adaptations, habitats, and other essential science concepts"-- Provided by publisher.