Why do some things glow under a UV/black light?

What do scorpions and teeth have in common? They both glow under a UV/black light! If you think about it, we see these types of lights quite often, in amusement parks, Halloween, bowling alleys, and even pest control. The real question is why do some things glow under UV/black lights, while others don’t?


A black light is actually a type of UV light, there are many types of UV or Ultraviolet lights, but the one in a black light is specifically UV-A. Ultraviolet light is a type of light with a less than normal wavelength, meaning it is out of the the visibility spectrum. UV lights are the the same type of light that emits from the sun. When these UV lights hit and reflect off of certain things, interesting reactions will happen. For example, when UV rays from the sun hit your skin you could get sunburned. In the case of a black light, when the UV light hits the chemical element phosphorus, it reacts by glowing. “Coincidentally”, phosphorus is common in plasma screen televisions, certain fabrics, teeth, fingernails, and scorpions! So if you’re ever at a bowling alley and your shirt, teeth, and fingernails start to glow, the answer is phosphorus!

Insect With Mechanical Gears

Adult Issus coleoptratus from Königsforst...

For hundreds of years, we believed that it was the Greeks that invented what is known today as the mechanical gear; which has enabled generations of technological advancement throughout all cultures.

In fact, it wasn’t the Greeks who invented functional mechanical gears; nature beat us to the punch once again!

A tiny leaf-hopping insect was recently discovered by scientists, which just happened to have an intricate mechanical gear system in its back legs.

Insect Has Mechanical Gears

Two scientists from the University of Cambridge recently discovered a leafhopper; one Issus coleoptratus. This leaf-hopping bug has interacting gears located at the top of the insect’s hind legs, used for propulsion. Its back legs lock together in an intricate gear system, and when both legs rotate back, they’ll lock. When the insect is ready to jump, these fine-toothed gears fire off, propelling the leafhopper forward at speeds as high as 9 miles per hour.

The reasoning for the insect having these mechanical gears… so each back leg can fire off at the same time.  If one hind leg were extended a fraction of a second earlier than the other one, it’d push the insect off course to the right or left, instead of jumping straight forward. Professor Malcolm Burrows, from Cambridge’s Department of Zoology says:

Unlike man-made gears, each gear tooth is asymmetrical and curved towards the point where the cogs interlock—as man-made gears need a symmetric shape to work in both rotational directions, whereas the Issus gears are only powering one way to launch the animal forward.

One fact that scientists found interesting, is that only the young leafhoppers had these mechanical gears on their legs. As they mature into adulthood, the young leafhoppers will shed their exoskeletons and fail to re-grow these gear teeth.

These mechanical gears found on the leafhoppers appear to be the only functioning gears found on any living organism. When these gears have been found on other living species, they have been only ornamental.

Cool huh!