Hierarchical structure and mechanical properties of fish scales from Lutjanidae with different habitat depths

In recent days, many researchers are focusing on emerging a new class of bio-inspired architectured materials. The primary strategy of these architecture designs is directly dependent on the types of available literature based on higher-ordered species such as nacre and fish scales. In this study, the authors have investigated the microstructural features and mechanical properties of five different ray-finned fish scales from Lutjanidae family collected in Iran. It was found that habitat depth and habits may result in significant changes in scale's surface morphology and mechanical properties. Interestingly, the variations in cross-sectional microstructural features such as fibre orientation and layer thickness ratios in scales did not show noticeable differences. It has also been proved that the mechanical performance of fish scales is influenced by the shape, array pattern and compactness of strips on posterior edges in a scale. Moreover, the radii count at anterior positions is higher in fishes living in wide-ranging depth; it supports in achieving higher scale stiffness and flexibility during movement. Consideration of these factors may help in optimising the performance of newly designed architectured materials subjected to mechanical loadings.