This book is an invitation to biologists to dust off their elementary physics and think about biological processes in Newtonian terms. In his straightforward text, Colin Pennycuick demonstrates how physical laws operate at all levels, from cells to ecosystems, and shows how to apply them with precision. Rediscovering the nature of physical properties can lead to new insights and understanding. Many examples are taken from the familiar world of zoology. One chapter deals with fractal geometry, a new way of measuring size, shape and scale. A new feature of Pennycuick's work is the extension of the biomechanical approach to ecosystem dynamics, the subject of the last two chapters. Students of animal behaviour, ecology and applied physics should enjoy working through the ideas of this volume.