0 a hard substance in the outer shell of insects and animals such as shrimp and lobster, and in the cell walls of some fungi -- 壳质（某些生物体表坚硬的保护层，如昆虫、虾，龙虾的外壳和部分真菌的细胞壁）
This serosa secretes a cuticle rich in chitin that protects the embryo against desiccation.
They are streaked with brown and purple and are housed in a transparent, gelatinous sheath composed of protein and chitin.
Chitin color differs between males and females, being blue for the males and aquamarine for females, deepening to purple in old age.
Many organisms can easily break down starches into glucose, however, most organisms can not metabolize cellulose or other polysaccharides like chitin and arabinoxylans.
The structure of chitin is comparable to the polysaccharide cellulose, forming crystalline nanofibrils or whiskers.
Activity on nascent and preformed chitin.
Accessory plates -long superficial strips of hard chitin, salient posteriorly.
The change in appearance of the developing shell layers as they became more fibrillar may reflect the formation of chitin-protein complexes.
