The field of systematics has developed remarkably over the last few decades. A multitude of new methods and contributions from diverse biological fields — including molecular genetics and developmental biology — have provided a wealth of phylogenetic hypotheses, some confirming traditional views and others contradicting them. There is now sufficient evidence to draw up a ‘tree of life’ based on fairly robust phylogenetic relationships. This book aims to apply these new phylogenies to an evolutionary interpretation of animal organ systems and body architecture. Organs do not appear suddenly dur ... More

The field of systematics has developed remarkably over the last few decades. A multitude of new methods and contributions from diverse biological fields — including molecular genetics and developmental biology — have provided a wealth of phylogenetic hypotheses, some confirming traditional views and others contradicting them. There is now sufficient evidence to draw up a ‘tree of life’ based on fairly robust phylogenetic relationships. This book aims to apply these new phylogenies to an evolutionary interpretation of animal organ systems and body architecture. Organs do not appear suddenly during evolution: instead they are composed of far simpler structures. In some cases, it is even possible to trace particular molecules or physiological pathways as far back as pre-animal history. What emerges is a fascinating picture, showing how animals have combined ancestral and new elements in novel ways to form constantly changing responses to environmental requirements. The book starts with a general overview of animal systematics to set the framework for the discussion of organ system evolution. The chapters deal with the general organization, integument, musculature, nervous system, sensory structures, body cavities, excretory, respiratory and circulatory organs, the intestinal and reproductive system, and spermatozoa. Each organ system is presented with its function, the diversity of forms that are realized among metazoan animals, and the reconstruction of its evolution.