How do some scorpions glow when light shines on it?

Do scorpions glow? Yes. That's an easy question to answer. It's a bit more difficult to pin down what exactly causes them to glow. In fact, scientists are still working on finding a firm answer to that question.

What scientists do know is that something in the scorpions' exoskeletons cause them to glow. Scorpions, along with other arthropods and insects, have an outer layer called a "cuticle." Unlike the cuticles on your fingers, which are made of hard or dead skin, the cuticle on a scorpion is a part of its exoskeleton. This cuticle has a thin section called the "hyaline layer." The hyaline layer is what reacts to ultraviolet (UV) light, such as black light or moonlight, and causes the scorpion's body to glow.

The hyaline layer is really strong and truly stands up to the tests of time. In fact, scientists have found that even fossilized scorpions glow under UV light. Additionally, when scientists preserve scorpion specimens in liquid-filled jars, the hyaline layer can make the liquid glow! Crazy, right?

While observing scorpions, scientists have noticed that the creatures don't glow immediately after molting. Rather, the cuticles have to harden completely before they shine blue-green in the starlight. But scientists still don't know if the glowing material comes from a chemical reaction in the hardening process, or if the scorpions actually secrete the glowing substance.