Among the millions of species in the world, there are many organisms that are active at night, and a few of these create their own light. Bioluminescence is a term that refers to the light created from chemical reactions within living organisms. There are relatively few organisms that can perform this function, but they cover a wide range of species including protists, which are single-celled organisms, bacteria, fungi, insects, marine invertebrates, and fish.
Aequorea victoria, bioluminescent jellyfish, by Sierra Blakely, May 2008; Motyxia sequoiae, California millipede, by Aggyrolemnoixytes, Jun 2023; Noctiluca scintillans, a dinoflagellate exhibiting bioluminescence by Naria Antonia Sampayo, Jun 2007
Bioluminescent species produce luciferin, a natural chemical, and luciferase, an enzyme. They have a special organ where the enzyme makes it possible to chemically combine luciferin and oxygen. The resulting mixture lasts only a brief moment as the oxygen breaks down the luciferin, and the reaction emits a photon of visible light. Light will be continually emitted as long as luciferin is pumped into the organ, so the length of time when light is produced can be easily controlled by the organism. Let’s look at a few different species.
Fireflies, one of the more familiar bioluminescent organisms that we can observe, make up over 2400 members of the beetle family, Lampyridae. Adult males and females both emit light, but males are generally either flying or perched at a slightly elevated position, while females are normally found near the ground. The pattern of flashes is unique to each species, and It is thought that males use their light to attract a potential mate. A female may flash back to indicate her location and interest. Firefly larvae live from one to three years while the adult phase only lasts for one to two months, long enough to find a mate and produce the next generation.
by Ylem, Aug 2009
Glowworms include certain fungus gnats and flightless beetles, and they comprise another group of bioluminescent organisms commonly found in many woodlands worldwide. The first species of glowworms that were positively identified were found in the 1940s, and more species are being discovered every year. They like damp, dark rock crevices, which they cover with sticky webs during the day. Resting under the webs at night, it is thought they use their light to attract prey which then get caught in the webbing. They do not bite, and are not harmful to humans.
Foxfire refers to a group of about 80 fungi species from among more than 100,000 fungi species found worldwide. Using the same chemicals and reactions, light can be emitted for longer periods of time from several minutes to several hours. People have been known to gather enough fungi together to brighten rooms and even to read by. The purpose of the light emission is unclear, but one thought is that it may attract insects that pick up fungal spores and disseminate them elsewhere during the insect’s travels, thus aiding in the reproductive process of the fungi.
Bioluminescent species are a fascinating and delightful group to observe and learn about. There are many publications for children and adults available through your local library or bookstore, in addition to visiting a nature center near you.