Light from Life

You can see some of the coolest lights ever being produced by an array of lifeforms, ranging from bacteria to fish. The word that describes these cool chemical lights is bioluminescence. "Cool" is correctly used here. In this amazing chemical reaction, nearly 100% of the energy is released as light, compared with only 10% for an electric light bulb. Just imagine if Thomas Edison could have accomplished this efficiency with the electric light bulbs he invented! The bulb in the lamp by which you are reading this article would then emit only light and not wasteful heat.

The biochemical "recipe" for cool light is much the same among the numerous types of organisms that can produce bioluminescence. The ingredients are luciferin, luciferinase, ATP, calcium or magnesium, and oxygen. Biologists think that bioluminescence evolved many times during the existence of life on Earth. Some scientists speculate that bioluminescence may have evolved when Earth's atmosphere began to accumulate oxygen. The free oxygen was toxic to some of the early inhabitants, and bioluminescence might have provided a pathway for detoxification.

Although the significance of bioluminescence is not always apparent in a particular organism, many uses have been demonstrated. Fireflies in the family Lampyridae use their cool tail lights for attracting the opposite sex. These cool lights can also be deceptive and can lead to a rendezvous with death for unsuspecting male fireflies. Female fireflies of the genus Photuris prey on males of different firefly genera by mimicking their flashing mating signals. When the amorous male responds to a female's return flash and arrives for the mating, he becomes her meal instead.

Bioluminescence can be used to startle or confuse, perhaps by temporarily blinding a potential predator. The flashlight fish has small cavities under its eyes that are jam-packed with bioluminescence bacteria. Some fungi use bioluminescence to advertise their presence and thus call attention to themselves.

Many species of marine plankton are also bioluminescent. While swimming or walking on the beach at night, you may have noticed a glow around you. Although it is not always understood why some organisms are bioluminescent, the simple fact that they are can have wide-ranging implications. The military is especially interested in understanding and predicting the locations of these bioluminescent plankton. Secret beach landings and silent-running submarines are easily revealed by the glow of these bioluminescent organisms.

Many genetic engineers are very interested in bioluminescence. What if it were possible to transfer genes that produce bioluminescence into organisms that do not bioluminesce? For example, what if pumpkins could be engineered to glow in the dark? Or if the bioluminescence gene could be used as a marker for tracking antibiotic resistance in various pathogenic bacteria? Bioluminescence is cool and can light up your life; it just depends on what species you are.