This comprehensive book incorporates systematic study of all invertebrate phyla from protozoa to hemichordata. It provides detailed description of representative genus of each of the major groups studied at undergraduate and postgraduate courses in zoology and life sciences. It gives contemporary accounts on adaptive morphology, anatomy, physiology, including diversity in the mode of locomotion, nutrition respiration, reproduction and varied life cycle pattern of representative genus. This adequately explained and immensely illustrated text with updated information will prove to be a valuable source for students and academics. The last chapter on conservation of invertebrates draws special attention of readers.