What makes a firefly glow?

Why do glowworms glow?

ONE OF THE MOST BAFFLING mysteries of the insect world has been what makes a firefly glow in the dark.

Lampyris noctiluca, common female European glow wormFireflies, also called lightning bugs, are luminous nocturnal beetles made up of about 1900 species living in tropical and temperate areas. The common glowworm is a member of the same beetle family (Lampyridae).

Fireflies range in size from a few millimetres up to about an inch (25 millimetres), and have special light organs under their abdomen. Females that lack wings are commonly referred to as glowworms.

There are a few peculiarities about fireflies, one of which is that some adult fireflies do not eat. Another is that frogs that eat large numbers of fireflies start to glow themselves.

Another mystery came to light in July 2008 when a researcher from the University of Queensland in Australia, David Merritt, found that Tasmanian cave glow-worms deep inside dark caves are able to tell whether it is day or night outside. Despite their continuously dark environment, they light up brightly during the day and switch off at night.

But the biggest mystery has been what causes them to glow.

Secret revealed at last

Neurobiologist Dr. Barry A. Trimmer was the lead author of a paper in the journal Science in which he finally revealed the secret of what makes a firefly glow.

The secret is nitric oxide. This is a dissolved gas that lets the firefly's nervous system switch on its flash of light. Most firelies produce short, rhythmic flashes.

In a complex arrangement between nerve cells, light-producing cells, and an enzyme-assisted reaction, the lightning bug's lantern emits that greenish glow so common in the early summer twilight in some parts of the world.

We must add of course, that even though scientists now know what makes the firefly glow, the whole complex arrangement shouts that only God, the Master Creator, could create and put together such an amazing little insect in the first place.

Glowworm photo by Wofl is licensed under Creative Commons Attribution ShareAlike 2.0 Germany License.

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