The text introduces fundamental biological concepts and the distinction between living and nonliving matter, explains energy flow via photosynthesis and animal respiration, and illustrates simple classroom experiments. It provides a systematic survey of animal groups from protozoans through sponges, polyps, echinoderms, worms, crustaceans, insects, molluscs, fishes, amphibians, reptiles, birds, and mammals, describing characteristic structures, functions, and life processes. Emphasis falls on observable anatomy, development, and ecological roles, accompanied by clear explanations and practical suggestions for beginner-level study and microscope work.