Effect of chemical composition and microstructure on the mechanical properties of fish scales from Megalops Atlanticus

Abstract

Fishes use their scales as a protection against external threats like environmental hazards and predators -- This work presents an experimental study of the microstructure, composition and mechanical properties of Megalops Atlanticus (Atlantic tarpon) scales -- Mechanical properties were evaluated in uniaxial tension as a function of position along the length of the fish (head, mid-length and tail) -- Additional tensile tests were performed in three different orientations (0°,45°, and 90°) to evaluate the anisotropic behavior of the scales -- Examination of fish scale microstructure and compositions were performed by using Scanning Electron Microscopy (SEM) and RAMAN spectroscopy -- The results showed that scales from Megalops Atlantiticus are anisotropic, with variations of mechanical properties as a function of body position -- Megalops Atlantiticus scales display a characteristic hierarchical structure composed of fibrous collagen layered structures and hydroxyapatite crystals that provide multifunctional characteristics, showing to have a non-homogenous distribution within the scale