High Concentrations of Zinc in the Fangs and Manganese in the Teeth of Spiders

ABSTRACT Various organisms have recently been shown to contain significant amounts of zinc and manganese in mechanical structures such as mandibular teeth. These accumulations are different from those in the bones and teeth of vertebrates and the shells and teeth of some mollusks in that the elements are both less common and are not obviously incorporated in biominerals. High concentrations of zinc (about 1 % of dry mass) were reported in the jaws of polychaete worms by Bryan & Gibbs (1979), using wet-ash analysis. These authors suggested that the zinc influences the mechanical properties of the jaw in a fashion analogous to the role of biominerals in the teeth of many organisms. Hillerton & Vincent (1982) detected zinc and manganese in the cutting edge of the mandibles of herbivorous insects from several orders using an electron microprobe. They determined the zinc concentration, averaged over the whole mandible, with wet chemical analysis, finding about 0·5% in a locust species. Hillerton et al. (1984) found either manganese or zinc in large quantities in the mandibles of separate species of beetles. Hillerton & Vincent (1982) went on to suggest that zinc may increase the density and fracture toughness of the mandibular teeth by increasing the number of secondary bonds in the cuticle. The hardening hypothesis has been accepted by Bone et al. (1983), who studied zinc in chaetognath teeth and spines, and by Perry et al. (1988), who studied zinc in copepod mandibles.