Chitin (C 8 H 13 O 5 N) n (/ ˈ k aɪ t ɪ n / KY-tin), a long-chain polymer of N-acetylglucosamine, is a derivative of glucose.It is a primary component of cell walls in fungi, the exoskeletons of arthropods, such as crustaceans (e.g., crabs, lobsters and shrimps) and insects, the radulae of molluscs, cephalopod beaks, and the scales of fish and lissamphibians. The structure of chitin is ...