Now that's it's (finally) springtime, it won't be long before we see some familiar lights in the night sky. We're not talking about stars, or even the Northern Lights. Instead, we're talking about fireflies.

Fireflies may be known for their glow power, but they're not alone. There are also deep-water fish and even bacteria that produce their own light. The fancy word for this phenomenon is “bioluminescence."

Fireflies never need to worry about replacing a light bulb or paying the electric bill. Their eternal light source is totally internal. Each blip of light is produced by a chemical reaction between a special protein called luciferase, a pigment called luciferin, and oxygen. Once the chemical reaction begins, the result is a bright little light.

Most bioluminescent creatures glow constantly, a bit like a light bulb with no off switch. What makes fireflies — sometimes called lightning bugs — unique and rare is their ability to turn their lights on and off. Researchers believe fireflies turn on their lights by sending signals from their brains to special light organs in their abdomens, where the light-producing chemical reaction takes place.

So why do fireflies spend so much time flipping the lights on and off? Fireflies are born knowing how to glow as larvae. Some people call them “glow worms."

Scientists believe bioluminescence serves a different purpose for larvae than it does for adult fireflies. Firefly larvae contain chemicals that are yucky or even toxic to other creatures. As wee worms, the light is more of a warning light that alerts anyone or anything on the hunt for a snack they may be better off looking elsewhere.

When it comes to adult fireflies, researchers believe bioluminescence serves two purposes: to attract a mate and to attract prey. Lightning bug blips happen in the blink of an eye, and while our eyes can't tell the difference, female lightning bugs know what they're looking for.

Researchers have found that female lightning bugs prefer “flashy" males. Some species of females prefer to mate with males that have the longest flash, while others prefer males that flash the fastest.

Scientists interested in the lightning bug's glow-power have recently discovered genetic information in the firefly's DNA responsible for producing luciferase. By implanting this light-producing gene into the cells of other animals, the researchers can observe those particular cells.

This is an especially exciting discovery for the medical community. With further research, it may one day become possible to make cancer cells glow so researchers can easily track the effectiveness of different treatments.

Luciferase is also used in forensic science. Investigators sometimes use a diluted solution containing this firefly enzyme to uncover tiny bits of blood the human eye may not detect at a crime scene.

Wonder What's Next?

We’ve already had Wonders of the Day about man’s best friend — the dog. Tomorrow we’re going to take an in-depth look at a girl’s best friend!