Metal–Halogen Biomaterials

American Entomologist • Volume 51, Number 1 The jaws, tarsal claws, stings, and other “tools” of a large fraction of arthropods, some worms, and members of other phyla contain extraordinary amounts of heavy metals (e.g., zinc, manganese, copper) and halogens (bromine, chlorine). Although the measured concentrations reach 25% of dry mass, the tissue is not filled with a biomineral, like calcified tissues are. Instead, metal–halogen biomaterials appear to be part of a distinctly different system that is widely found among small organisms. Very little is known about the form and function of these biomaterials or their role in the behavior, ecology, and evolution of invertebrates.