Biological Armors-Evolution, Materials, and Bioinspiration

Biological armors have evolved across taxa as structural adaptations that provide protection from external forces while balancing mobility, metabolic cost, and functional trade-offs. These systems, from arthropod exoskeletons to vertebrate osteoderms, illustrate how natural selection shapes materials and morphology to optimize defense without compromising essential movement and physiological processes. The evolution of armor is constrained by biomechanical limits, as seen in the structural rigidity of heavily plated organisms and the flexible composites that integrate protective and dynamic properties. Methods used to study these systems-CT scanning, histology, finite element analysis, and mechanical testing-directly influence how the biological principles of armor are defined and understood. These approaches reveal the material properties and functional constraints of armored structures that can be translated into engineered applications through bioinspiration. Bioinspired designs informed by natural armor have led to innovations in impact-resistant materials, flexible ceramics, and modular protective systems. By integrating biomechanics, materials science, and evolutionary biology, this manuscript examines how armor evolves, functions, and informs bioinspired design.