Fracture resistant bones: unusual deformation mechanisms of seahorse armor

Multifunctional materials and devices found in nature serve as inspiration for advanced synthetic materials, structures, and robotics. Here, we elucidate the structural mechanics and unusual deformation mechanisms discovered in seahorses that provide them prehension and protection against predators. The seahorse tail is composed of subdermal bony plates arranged in articulating ring-like segments that overlap for controlled ventral bending and twisting. The bony plates are fracture resistant materials designed to slide past one another and buckle when compressed. This complex plate and segment motion, along with the unique hardness distribution and architectural hierarchy of each plate, provide seahorses joint flexibility while shielding them against impact and crushing. Mimicking seahorse armor may lead to novel biomimetic technologies, such as flexible armor, fracture resistant structures, or prehensile robotics.