While the glow-in-the-dark animals featured in this article operate through a natural process of bioluminescence, scorpions differ by glowing only under fluorescent ultraviolet light. Scorpions possess a number of small “eyes” along their bodies, prompting some researchers to suggest that the entire fluorescent exoskeleton itself functions as a light sensor. This has led to the widespread use of UV lights to quickly spotlight the predatory arthropods during scorpion research surveys. For the scorpions themselves, the ultraviolet fluorescing exoskeleton might be used to pick up the shadows of starlight and moonlight.

Like fireflies, scorpions inhabit every continent except Antarctica. They feed on a wide variety of small prey that they catch in their claws, following up with their notorious stinging tail. Interestingly, less than 2.5 percent of the more than 1,000 scorpion species in the world are deadly to humans.