Microstructure and mechanical properties of fish scales from MegalopsAtlanticus

This work studies the microstructure and mechanical properties of fish scales from Tarpon fish (MegalopsAtlanticus) with cycloid scales. Mechanical properties of the scales were evaluated in uniaxial tension from three different positions along the length of the fish (head, mid-length and tail), similarly it was evaluated the effects of dehydration of the material in the mechanical properties, demonstrating an increased stiffness as a function of dehydration also reported Garrano et al. for CyprinusCarpio [1]. Microstructural analysis revealed that the scale is composed by different layers associated with collagen to form a plywood like structure and a top layer associated with hydroxyapatite, as it has just been reported by several authors to different fish species [2 , 3, 4]. This combination of collagen and hydroxyapatite layers allows the fish scale to have a high penetration resistance [5]. Microstructural analysis also reveals that the scale have a rugged circular concentric pattern on top to provide advantages associated with hydrodynamic, unlike the inner part of the scale that is in contact with the dermis which presents a smooth surface. Thus all these microstructural and mechanical characteristics are used by fish as drag reduction system, mobility and increase protection against predators, which are desirable features in engineering applications through the design of bioinspired materials.