This work provides a clear foundation, based on physical biology and biomechanics, for understanding the underlying mechanisms by which animals have evolved to move in their physical environment. It integrates the biomechanics of animal movement with the physiology of animal energetics and the neural control of locomotion. The author also communicates a sense of the awe and fascination that comes from watching the grace, speed, and power of animals in motion. Movement is a fundamental distinguishing feature of animal life, and a variety of extremely effective mechanical and physiological designs have evolved. Common themes are observed for the ways in which animals successfully contend with the properties of a given physical environment across a diversity of life forms and varying locomotor modes. Understanding the common principles of design that span a diverse array of animals requires a broad comparative and integrative approach to their study. This theme persists throughout the book, as various modes and mechanisms of animal locomotion are covered.