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Flight Lines: Night-lights from natural sources

Panellus stipticus is one of 65 species of bioluminescent fungi in the world, according to the National Science Foundation. Photo by Ylem

That we as a species have a fascination, a need even, for light is not in doubt. In its absence there is only deep, glooming dark.

With dark comes unease, trepi-dation, even fear. Imagine the days of prehistoric cave dwellers and the anxiety that permeated everyone’s psyche with the setting of the sun.

I am sure a fire was kept burning in the middle of the room every night. It would not only bring warmth, but an easing of the nightly discomfort brought by the darkness.

Somewhere in our history we began to use more reliable sources to produce light – peat, coal, various oils, etc. Then came this magical thing called electricity, and with it came the ease with which we could now conjure light. While Thomas Edison did not invent the electric lightbulb (there were many before him), he did manage to come up with the first commercially practical incandescent light. With a simple flick of a switch, keeping the dark at bay became an afterthought.

Over the eons, the natural world found ways to overcome the darkness as well. Apart from the fluorescence that occurs in some minerals after exposure to certain energy sources, there exists a wide array of creatures, great and small, with the ability to produce their own light – chemically – in a manner known as bioluminescence.

(Technically, bioluminescence is chemiluminescence that takes place inside a living being.)

Without getting too deep into chemistry, the process simply requires the combining of two chemicals: Luciferin (the compound that produces the light) and either luciferase or a photoprotein. Unlike electrical lighting, this process is “cold.”

In other words, all of the energy produces light instead of only about 10 percent of our familiar incandescent lights, the rest being lost to heat.

Whether used to hunt prey, defend against predators, find a mate, or some other vital life function, most of the organisms known to bioluminesce are found in the oceans. Early mariners were certainly familiar with the glowing water in their ships’ wakes during some nights. That’s caused by a type of phytoplankton known as a dinoflagellate.

Cephalopods like some cuttlefish and squid exhibit the ability to self-illuminate. Yet, perhaps the best-known marine creature armed with this aptitude is the anglerfish.

This is the creepy-looking beast with the huge teeth that dangles a glowing “worm” from the top of its gigantic head. When smaller, curious fish come to investigate the light, well, it’s a short trip to the anglerfish’s mouth from there.

Terrestrially, bioluminescent organisms are relatively limited. Sitting atop of my “cool to see someday” list is the only land snail capable of this found in the tropics of Southeast Asia. Another phenomenon I would like to witness is something known as “foxfire.”

This is the glow of certain fungi found on decaying wood. If someone knows of such a location, I’d love to hear about it.

Easily the most familiar example of bioluminescence to average Midwesterners is that of fireflies. What kid hasn’t run around outside trying to capture “lightning in a jar” by trapping a few fireflies? Thousands of species of this type of beetle exist on every continent except Antarctica. They are very common in the tropics. All require a somewhat moist environment. Fireflies are thought to use their persistent flashing for a number of reasons including attracting mates, defending territory, and warding off predators.

I was reminded just how fascinating this insect is within the past week when, while driving after dark through an area rich with flying bugs, I struck one with my windshield.

While I couldn’t discern the smashed body of this small beetle in the dark, its flattened remains glowed persistently for several seconds.

I sometimes wonder if a situation such as this wasn’t behind the original idea of the popular glow sticks, so common these days at concerts and other venues. After all, the process of producing light – the combining of two different chemicals – is virtually the same. In other words, both use chemiluminescence. It’s just that one takes place within the abdomen of a beetle, the other within a plastic tube.

Regardless, both represent a unique and fascinating way to produce light in an otherwise dark world.