Includes bibliographical references and index

"Sea mammals rely on marine ecosystems for their survival, but some of them--like polar bears and seals--only spend part of their time in water. Readers dive into the world of sea mammals in this volume, learning about the many kinds, their habitats, their diets, and the harmful impact global warming is having on their homes. In comparing and contrasting different sea mammals, readers learn about the needs and roles each of them have and play, as well as why it is so important to protect the Earth from climate change. Beautiful photographs accompany helpful text and sidebars to engage readers in STEM content from outside the classroom"-- Provided by publisher