Elemental and phase analysis of the stomatopod dactyl club by X-ray mapping

Nature creates multifunctional composite materials by assembling organic and inorganic constituents into complex hierarchical structures. The ability to precisely control the phase, morphology, and local distribution of components has resulted in a number of unique biological materials that exhibit a wide range of mechanical properties. One such structure is the raptorial appendage (dactyl club) of Odontodactylus scyllarus, a species of stomatopod (marine crustacean). The dactyl club is a multiphase bio-composite material that exhibits exceptional damage tolerance from high energy loading events. Here we examine and quantify the local distribution of elements within the dactyl club by means of XRM and quantitative EDS. We identify distinct phases, which are then correlated with ultrastructural and mechanical analyses to derive structure-function relationships as well as provide insight into the formation of an impact-resistant natural material.