There’s a great post over at Charismatic Megafauna showcasing the beauty of fluorescent arthropods:
Scorpions have “cuticular fluorescence.” Basically, compounds in their exoskeleton absorb and re-emit ultraviolet light as visible light (light humans can see). The exoskeleton of an arthropod is made from composite materials that are both strong and flexible. It’s the outermost layer, epicuticle, that produces the glow, and it seems to be something that changes chemically as the animals grow…
Some interesting ideas have been proposed for why scorpions and other arthropods glow like this. While humans can’t see UV light, most insects can, and much of the world around uslooks quite different in UV light. Some experiments show that scorpions may use presence of UV light as a way to detect shelter. (They determined this by putting tiny little goggles on the scorpions that blocked their vision…)
Go read more!