This textbook has been designed to meet the needs of B.Sc. (Hons.) Second Semester students of Zoology as per the UGC Choice Based Credit System (CBCS). Comprehensively written, it explains the essential principles, processes and methodology of Coelomate Non-Chordates and Cell Biology. This textbook is profusely illustrated with well-drawn labelled diagrams, flow charts and tables, not only to supplement the descriptions, but also for sound understanding of the concepts.