So much has to be crammed into today's biology courses that basic information on animal groups and their evolutionary origins is often left out. This is particularly true for the invertebrates. The second edition of Janet Moore's An Introduction to the Invertebrates fills this gap by providing a short updated guide to the invertebrate phyla, looking at their diverse forms, functions and evolutionary relationships. This book first introduces evolution and modern methods of tracing it, then considers the distinctive body plan of each invertebrate phylum showing what has evolved, how the animals live, and how they develop. Boxes introduce physiological mechanisms and development. The final chapter explains uses of molecular evidence and presents an up-to-date view of evolutionary history, giving a more certain definition of the relationships between invertebrates. This user-friendly and well-illustrated introduction will be invaluable for all those studying invertebrates.