Material properties of arthropod cuticles: The arthrodial membranes

Abstract

1. On the basis of tensile mechanical properties fibre-reinforced arthropod cuticles can be classified into two main types: one in which the stiffness is provided mainly by the matrix and the other in which stiffness derives largely from the chitin fibres. 2. These two types of cuticle can be related directly to function: the former is relatively hard and stiff and typical of sclerites and thus imparts skeletal rigidity and chiefly subserves a protective function, the latter gives rise to relatively soft and supple, yet flexible materials commonly encountered in arthrodial membrane cuticle. 3. Some cuticles show elements of both of the above types. It appears that these intermediate cuticles are specialized forms and occur as optimizations between the main functions of protection and locomotion, as in caterpillars. 4. It is concluded that a description of arthropod cuticle in mechanical terms is better suited to the understanding of function and is therefore biologically more meaningful than are classifications based on either fibre architecture or histological staining reactions.