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Why
do fireflies light up?
The Chinese thought these twinkling little creatures came from burning grass.
A European
legend warned that if a lightning bug flew in the window, someone
was going to die.
Aztecs used the term firefly metaphorically, meaning a spark
of knowledge in a world
of ignorance or darkness. American Indians collected
lightning bugs and smeared
them as decorations on their faces and chest.
The
firefly is much more efficient than man in producing a "cold light",
containing no ultra
violet rays, with a pale yellowish or reddish green in
color and a light efficiency of 96%.
The ordinary incandescent light has an
efficiency of roughly 10%, most of the energy
being wasted as heat. The light-producing
organ is located in the sixth, or the sixth
and seventh abdominal segments.
The
taillight contains two rare chemicals, luciferin and luciferase. Luciferin, a
heat resistant
substrate, is the source of light; luciferase, an enzyme, is
the trigger; and oxygen is the fuel.
A
body chemical, ATP (adenosine triphosphate), converts to energy and causes the
luciferin-luciferase mixture to light up. Small internal injections of ATP in
the firefly tail
cause flashes of light that can be measured quantitatively.
If you will notice, the firefly
turns on its light when flying upward, at
intervals of about 5.8 seconds. In the dark
periods it coasts downward again.
You may also have noticed that hundreds of
them synchronize their flashes
to appear simultaneously. As
all living cells contain ATP in a rather constant concentration, injection of
the
firefly's chemicals quickly detects energy problems in human cells (different
reaction
between normal and cancerous cells). The firefly technique is used
to study heart
disease, muscular dystrophy, urology, antibiotic testing, waste
water treatment, and
environmental protection. Luciferin and luciferase are
used in research on cancer,
multiple sclerosis, cystic fibrosis and heart
disease. The
ability of these insects to produce cold light (bioluminescence) has led to new
flashlights
and flares on the market today. Special electronic detectors,
using firefly chemicals,
have been placed in spacecraft to look for earth-life
forms in outer space. When as little
as one quadrillionth of a gram of ATP
enters the rocket's detector, a flash of cold
light is given off and the signal
is recorded by scientists on earth. Other detectors
warn that milk, food or
water may be bacteria contaminated. .From
... Ohio State University
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