How do scorpions glow under ultraviolet light?

Scorpions have compounds in their cuticle that fluoresce when exposed to ultraviolet light, making them appear bright blue-green under a black light. Scientists believe the glow may help scorpions detect light levels or avoid too much exposure, though the exact biological purpose is still debated. The effect is not the same as bioluminescence, because the light comes from outside illumination rather than a chemical reaction inside the animal. This trait is so consistent that scorpions are often easy to spot at night with UV light.