Call them fireflies,
lightening bugs, glow flies or moon bugs, everyone seems to love those bioluminescent bugs you find on any good summer's night. While many of us enjoy watching and
catching these bugs, most people don't fully understand how these insect
produce the light that so eagerly attracts us to them. Most commonly known by
the name of fireflies, these insects belong to a family of beetle known as Lampyridae, meaning "glowworm"
or "to shine". This family of beetles holds all 2,000 species of
fireflies worldwide. Most of these species are found around moist environments in
Asia, Europe and the America 's.
While not all species of fireflies emit light, those that do are almost
exclusively nocturnal. The fireflies active hours during the night allow it to use their light and is the reason we can find them! Most fireflies use
their light to attract mates of the same species and some even use them to attract
prey for a midnight snack!
The light
made by fireflies is due to two special bioluminescent compounds found within
the abdomen of the insect. The first, luciferin, is an organic, multi-ring structured compound created within the
insect. A second compound, called luciferase, is an oxidative enzyme also
created by the insect. When these two compounds, luciferin and lucifrase mix in
the presence of oxygen and magnesium, an instant chemical reaction occurs. The
lucifrase enzyme breaks down parts of the luciferin compound releasing energy. This
energy following the reaction is then emitted as light. This light emitted is
the blinking we can see through the firefly's translucent abdomen! The length
and brightness of the blink is determinate on the amount of the compounds
released in the insect's body and how fast they release this amount.
To take this even one step further, different
firefly species can produce different colors of light based on how they form
their light emitting chemicals. Small variations in luciferin's chemical composition change the color of the light emitted. Their are 3 known variations in luciferin
which result in green, yellow or a pale red light! Some fireflies can also use
a combination of these variations in the compound to make more of a yellow-green
or orange blink. The colors of variations are shown below:
Another interesting factor about the
light created by fireflies is that it's known as a "cold light". As
with most bioluminescent animals, the light emitted by the organism is so energy
efficient that all the energy is emitted only within the visible light spectrum.
Since the energy expenditure in creating the light is so energy efficient, the
reaction produces no heat or other byproduct and is aptly named "cold
light". Releasing light in only the visible spectrum also eliminates the
risk of the organism overheating or wasting energy in inefficient methods. To
put this into perspective lets compare a firefly's light to our man made light bulbs.
Using an incandescent light bulb over 90% of the energy you use to run the
light bulb is emitted as heat, not light! Even when using a florescent light bulb, about 10% of the energy used to run the light is still lost as heat. Compare
this to the firefly and you'll find that 0% of the energy is lost as heat.
For more information on Fireflies visit these sites:
(Time lapse photo of fireflies "blinking" in a
meadow.)
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