Hippos are unusual in being genuinely amphibious. This has a fundamental effect on their physiology and way of life. Following a general introduction, there is a detailed description of hippo anatomy and physiology, including facts about their skin structure and physiology. Subsequent chapters are devoted to their social biology and ecology, including descriptions of their breeding and feeding ecology. Several extraordinary instances of carnivory, including an instance of cannibalism, are described. This book closes with three chapters devoted to the results of the author's survey on the distribution and abundance of the common hippo throughout Africa.