How do dolphins catch fish in murky water? Why do moths drink from puddles? How do birds' eggs breathe? How do animals work? In this revised and updated edition of the acclaimed text Animal Physiology, the answers are revealed. In clear and stimulating style, Knut Schmidt-Nielsen introduces and develops the fundamental principles of animal physiology according to major environmental features - oxygen, food and energy, temperature, and water. The structure of the book is unchanged from the previous edition, but every chapter has been updated to take into account recent developments, with numerous new references and figures. Animal Physiology is suitable as a text for undergraduate and beginning graduate courses in physiology. As with previous editions, students, teachers as well as researchers will find this book a valuable and enjoyable companion to course work and research.