You likely have nostalgic childhood memories of catching fireflies in a mason jar. If you happen to be one of the few kids who never captured lightning bugs, then you must have, at least, been in awe of their seemingly magical ability to flash a bodily glow at evenly spaced intervals. Even after reaching adulthood, it is hard not to recognize fireflies as possessing a truly unique ability. After all, how many other insects, or any type of organism, do you know of that can glow? Algae, maybe? Well, as it happens there are many arthropod species that are capable of glowing, but why they glow is another question that science has yet to answer. Certain spider, scorpion, and even cockroach species are known for their glowing ability. Considering all the natural phenomena that science has come to explain, it is surprising to learn that researchers only understand the physiology behind the glowing ability of certain scorpion species, and of course, lightning bugs.
The glow of lightning bugs and other arthropods is known as “bioluminescence.” However, the internal bodily mechanisms that produce bioluminescence in lightning bugs is entirely different in scorpions. Scorpions glow by means of “fluorescence,” which still falls under the category of luminescence as opposed to incandescence. The exoskeletons of scorpions contain certain molecules that absorb ultraviolet light before re-emitting visible light. The outermost layer of a scorpion’s exoskeleton is called the “epicuticle,” and this is where the glow originates. The reason why some insects glow under UV light is not fully understood. Although humans cannot see UV light, insects can see it, whether they glow or not. The outside world appears quite different when UV light can be detected. One reason as to why insects see UV light may be to locate shelter. This theory was proposed after researchers put tiny UV light-blocking goggles on scorpions. These goggled scorpions seemed to have more difficulty than normal when it came to locating shelter. Another theory suggests that scorpions and other insects inherited the ability to detect UV light as an adaptation that allowed them to tolerate the intense sunshine that their earlier sea-dwelling ancestors had not been exposed to. While these theories are plausible, there may be no way of discovering why insects adapted to detect UV light.
Would you find it interesting to wear glasses that allow you to detect UV light so that you could see the world like an insect?