Scorpions enhance their claws and stingers with metals, akin to wearing steel-capped boots. This adaptation serves to amplify the strength of their primary weapons.

The notion of metal reinforcement is already known in vertebrates, such as the teeth of Komodo dragons (Varanus komodoensis), where metal-rich areas are perceptible as dirt on the surface.

Sam Campbell and researchers from the University of Queensland, Australia, investigated the claws and stingers of 18 diverse scorpion species to analyze the extent and composition of metallic reinforcement.

The team employed advanced X-ray imaging techniques and an electron microscope, mapping the presence of three primary metals: iron, zinc, and manganese. Additional elements, including copper, nickel, silicon, chlorine, titanium, and bromine, were also detected.

Metals mainly accumulate at the tips of stingers and the cutting edges of claws, as well as in the mouth and tarsal claws, which Campbell likens to “a boot with a steel cap on the toe.” Although the rest of the exoskeleton is also hard, it is much softer in comparison.

All scorpions emit a green or blue glow under ultraviolet light, yet the researchers discovered that the metal-enriched areas do not fluoresce under UV exposure.

While the method by which scorpions acquire these metals remains unclear, their diet is likely a significant source.

The research indicates that different scorpion species accumulate metals variably according to their behaviors. “Our findings suggest that the more zinc in the nail, the less zinc in the stinger, and vice versa,” explains Campbell. “Since scorpions utilize their weapons distinctively, metal enrichment likely evolved to enhance the biomechanical properties of the most critical weapons.”

Metal incorporation in animal tissues appears to be more prevalent than previously recognized, notes Aaron LeBlanc from King’s College London. “Emerging research indicates similar traits in vertebrate teeth,” he adds. “The next logical phase is to explore the evolutionary pathways of these adaptations across major lineages, and this research is groundbreaking in that context.”