Synopsis This book entitled Invertebrates deals with the morphology, anatomy, physiology and development of important animals of non-chordates. The publication of this book is according to the syllabi for B.Sc as well as M.Sc students of Indian universities. Many other books published on this topics is said to include some of Indian types and not all, so effort is taken to explain almost all the important Indian types. Efforts have also been taken into consideration to condense the matter as far as practicable. It is hoped that this book will not only meet the requirement of the students but the useful as a guideline to the learners as well.