Arthropod exoskeleton

An arthropod exoskeleton is an external, jointed covering made largely of chitin and protein. It supports the body, protects tissues, and must be shed for growth.

Chitin: A structural polysaccharide found in arthropod exoskeletons and fungal cell walls. This polymer forms the exoskeleton’s main fibrous framework.
Epicuticle: The thin outermost layer of arthropod cuticle, typically lacking chitin. This surface layer helps limit water loss and resist chemical exposure.
Insect wing: An outgrowth of an insect’s body wall used chiefly for flight. Wings are cuticular structures whose support and flexibility enable flight.
Endoskeleton: An internal framework of rigid structures that supports and protects an animal’s body. Unlike an exoskeleton, it grows within the body rather than being shed as a covering.
Arthropod cuticle: The nonliving outer covering secreted by the epidermis of an arthropod. Its layered structure makes up the exoskeleton’s material body.
Procuticle: The chitin-and-protein layer beneath an arthropod’s epicuticle. Most of the cuticle’s thickness and mechanical strength lie here.
Insect molting: The periodic shedding and replacement of an insect’s cuticle as it grows. Insects demonstrate how exoskeletal growth depends on successive molts.
Hydrostatic skeleton: A support system in which fluid pressure within a body cavity enables movement and maintains shape. This support system avoids the exoskeleton’s rigid external plates.
Sclerotization: The chemical hardening of arthropod cuticle through cross-linking of proteins and other molecules. It stiffens selected cuticle regions while joints remain flexible.
Exocuticle: The hardened outer portion of arthropod procuticle. Its rigidity contributes to protection and structural support.

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