This chapter presents a wide range of examples of fibrous composites in animals and plants. A sensible amount of such ‘stamp collecting’ is justified because it shows the widespread distribution and importance of fibrous architecture (especially plywood types) in biological systems. The presentation in this chapter is systematic (by taxonomic groups) rather than comparative, for ease of access. The various types of material are described, illustrated, and listed in tables. Systems used in experiments on control of fibre directions are included.

Parallel fibres

Insect tendons and ovipositor drills

In examples where mechanical stresses are likely always to act upon a structure from a constant direction, the fibrous component can be aligned in parallel (as in Fig. 1.3C). This applies to the chitin crystallites in the tendons of insects, on which a muscle always pulls from a specific direction; it is well shown in the long tendon running throughout the length of the hind tibia to operate the tarsal joints in the large hind legs of crickets (e.g. Decticus verrucivorus) and grasshoppers (e.g. the locust Schistocerca gregaria). A scanning electron micrograph of a locust tendon showing parallel chitin is shown by Bennet-Clark (1976). Other good examples are the ovipositors used for drilling wood by wood wasps (e.g. Sirex gigas) (Rudall, 1967) and their ichneumonid parasitoid (Rhyssa persuasoria). These samples of paralleloriented chitin are ideal for X-ray diffraction (Rudall, 1967) and for infra-red absorption studies (Neville, 1975a, 1980).