Cuticle - Invertebrate Zoology

Invertebrate Zoology

In zoology, the invertebrate cuticle or cuticula is a multi-layered structure outside the epidermis of many invertebrates, notably roundworms and arthropods, in which it forms an exoskeleton (see arthropod exoskeleton).

The main structural components of the nematode cuticle are proteins, highly cross-linked collagens and specialised insoluble proteins known as "cuticlins", together with glycoproteins and lipids.

The main structural component of arthropod cuticle is chitin, a polysaccharide composed of N-acetylglucosamine units, together with proteins, lipids, and catecholamines The proteins and chitin are cross-linked by catecholamines such as N-acetyldopamine, contributing to their rigidity. The rigidity is a function of the types of proteins and the quantity of chitin and catecholamines. The more acidic the protein is, the softer the cuticle. It is believed that the epidermal cells and hemocytes (cells in the hemolymph) produce protein and also monitors the timing and amount of protein to be incorporated into the cuticle.