Chitin (C8H13O5N)n, a lang-cheen polymer o N-acetylglucosamine, is a derivative o glucose. It is a primar component o cell waws in fungi, the exoskeletons o arthropods, sic as crustaceans (e.g., crabs, lapsters an shrimps) an insects, the radulae o molluscs, cephalopod beaks, an the scales o fish an lissamphibians. The structur o chitin is comparable tae anither polysaccharide - cellulose, formin crystalline nanofibrils or whiskers. In terms o function, it mey be compared tae the protein keratin. Chitin haes pruived uisefu for several medicinal, industrial an biotechnological purposes.