Through study of locomotion of living creatures, Akira Azuma has come to the conclusion that every creature is made and moves in a manner that is best suited to its environmental conditions. Thus, one purpose of this book is to shed light on the physical relationships among habitat, form or life, and mode of movement in living creatures. The text also reviews results of theoretical and empirical research carried out by various scientists over the years. Each of the two main parts of the book, "Flying Dynamics and Swimming Dynamics", is written from the viewpoint of mechanics, specifically fluid dynamics, rather than from the viewpoint of physiology and ecology. Thus the chapters and sections are organized according to mechanical, not biological principles. However, Azuma hopes that the book will prove to be useful reference not only to engineers working and studying fluid and flight dynamics, but also for biologists using mechanical analyses to gain a better understanding of the behavior of animals and the mechanical functions of the body parts in relation to their forms and modes of locomotion.