From the giant bottlenosed whale and the West Indian manatee to the crabeater seal and hourglass dolphin, from the pygmy sperm whale to the spotted-necked otter, marine mammals are among the most fascinating - and most watched - of the Earth's many animal species. Some, such as dolphins, are known for their intelligence, friendliness toward humans and sophisticated social behaviour. In addition, all these animals are sources of fascination for the special adaptations they have undergone for life in and around the water, for their unique methods of communication ("whale song") and for the endangered status of many species. Ronald M. Nowak offers a comprehensive guide to this fascinating and varied order of mammals. The book includes scientific and common names, the number and distribution of species, measurements and physical traits, habitat, daily and seasonal activity, population dynamics, home range, social life, reproduction, longevity and status of threatened species. A foreword by John E. Heyning is written for the general reader, while a more detailed and substantive introduction by Randall R. Reeves and Brent S. Stewart discusses issues in greater depth for the specialist. Illustrated with more than 140 detailed black-and-white photographs, this book is aimed at marine mammal experts and enthusiasts alike.