The majority of undergraduate texts in invertebrate zoology (of which there are many) fall into one of two categories. They either offer a systematic treatment of groups of animals phylum by phylum, or adopt a functional approach to the various anatomical and physiological systems of the better known species. The Invertebrates is the first and only textbook to integrate both approaches and thus meet the modern teaching needs of the subject. This is the only invertebrate textbook to integrate systematics and functional approaches. The molecular systematics sections have been completely updated for the new edition. Strong evolutionary theme which reflects the importance of molecular techniques throughout. Distills the essential characteristics of each invertebrate group and lists diagnostic features to allow comparisons between phyla. New phyla have been added for the new edition. Stresses comparisons in physiology, reproduction and development. Improved layout and illustration quality. Second edition has sold 14000 copies. Nature of the first edition: Students will like this book. It deserves to succeed.