Welcome to brainstuff from how stuff works. Hey, brain stuff, Lauren vocal bomb here. Some animals are just over the top. Take scorpions. Is it not enough that these stinging arachnids can survive some of the harshest climates in the world and live twenty five times longer than your average cockroach? Or that some species don't need males to reproduce and can live up to forty eight hours without oxygen, and that all of them will eat almost anything they can subdue,
even other scorpions. No, it's apparently not enough, because scorpions also glow electric cian green under ultra violet light. Why they do this is a bit of a mystery, but it makes them pretty easy to study. All a scorpion researcher and has to do to find scorpions is go out into the desert at night with a black light and watch those suckers light up like Christmas trees. Chemically speaking, nobody's exactly sure what causes scorpions to glow, but we
know it's power full stuff. When a scorpion is preserved in alcohol, the alcohol itself will fluoresce. Scorpion fossils have even been induced to glow under black light after hundreds of millions of years. What we do know is the chemicals that make a scorpion so rave ready are in the outer layer or cuticle, of its exo skeleton. Scientists
call it the highland layer. Scorpions molt their exo skeleton every so often in order to grow, and researchers have observed that until the slightly mushy outer shell has entirely hardened, the highland layer does not fluoresce under UV light. This is all pretty weird. Why would an animal evolve to glow under ultraviolet light? Researchers have posited a bunch of different ideas. Scorpion fluorescence might help them find each other in the dark, protect them from sunlight, or even confuse
their prey. But there's another promising theory that scorpions are somehow using their fluorescence to detect UV light, mostly because they want to avoid it. There night hunters, after all, and a scorpion will always find the darkest place to hang out during the day or even in the moonlight. A study published in the Journal of Arachnology tested normal fluorescing scorpions and a group of scorpions that they had reduced the fluorescence of with prolonged exposure to UV light.
The normal scorpions then reacted more strongly and negatively to UV light than the desensitized scorpions. But wait, you might be thinking. Scorpions still have eyes, and as it turns out, they can visually see light within the ultra violet part of the spectrum, but it doesn't seem like the scorpions were reacting visually. A separate study published an Animal Behavior in basically blindfolded a group of scorpions and found that the critters still reacted to the presence of ultraviolet light.
So it seems that they're using their entire bodies as giant UV seeking eyeballs, and that if they sense that they're glowing at all, it's time to scurry up somewhere darker. Today's episode was written by Jesseline Shields and produced by Tyler Clang. For more on this and lots of other glowing topics, visit our home planet, how stuff Works dot com.