Figure 1. Hierarchical structure of cuticle of stomatopod (mantis shrimp).

(a) Morphology of the stomatopod (a1). The red rectangle shows the telson sample (a2) used as sample for synchrotron scanning-WAXD test after dissection; (b) SEM image (b1) from a cross section of the cuticle shows the lamellar structure. The epicuticle (epi), exocuticle (exo), endocuticle (endo) and membranous (ml) layers are indicated. The three higher magnification SEM images show different fibre stack intensities across exocuticle (b2), endocuticle (b3) and membranous layer (b4); (c) The hierarchical structure of cuticle starts from N-acetyl-glucosamine molecules arranged in an orthorhombic crystal structure (c1) (image taken from⁵⁰) with 18 to 25 chitin molecules wrapped with proteins form nanofibrils (blue cylinder in c2), together with minerals, the nanofibrils cluster into nanofibres (c3), the chitin fibre-protein planes stack into plywood structure with fibre-protein planes rotated around the normal axis of the cuticle (c4). The plywood (Bouligand) structures with in-plane (IP) fibres together with the out-plane fibres (OP) running through the pore-canal system in the cuticle (c5).