In recent years, a number of scientists have had success with transferring the genetic material responsible for bioluminescence into plants that don’t normally glow in the dark. The goal is to eventually develop glowing trees that also function as streetlights, and indoor plants to replace household light fixtures, saving a tremendous amount of electrical energy in the process. So far, they have produced plants that glow faintly in the dark, so it may be a while before the technology is feasible for widespread application. In the meantime, here are some of the fascinating creatures that have served as muses for these cutting-edge scientists, as well as the rest of humanity since time immemorial.
There are approximately 2,000 species in the Lampyridae family of beetles, most of which produce a glow in their abdomen. Firefly bioluminescence is most often part of courtship and mate selection behavior, though some species also use the effect to attract their prey. Some fireflies exhibit simultaneous flashing patterns rather than the random display of flashing that most of us are accustomed to on warm summer nights. The biology of bioluminescence in fireflies has been studied for centuries, and scientists now have a detailed understanding of the phenomenon: in short, firefly bioluminescence is a result of a chemical interaction between the compound Luciferin, the glowing substance, and Luciferase, an enzyme that causes the Luciferin to emanate light.
Fireflies are commonly referred to as glowworms while in their larval stage, but there are many other unrelated species that share the trait of bioluminescence. Arachnocampa is a species that lives in caves and grottos of Australia and New Zealand. This peculiar creature spins silken threads much like spiders do, but these threads are suspended in single lines from cave roofs. The threads are covered in poisonous mucus and are intended to trap prey, which are attracted by the glowing worms.
A number of species in the genus Vibrio have bioluminescent abilities which can take several different forms. The form most commonly experienced by humans is the sparkle of crashing waves at night, which occurs periodically in both tropical and temperate seas. In this case, the glow is triggered by movement and can also be observed when sloshing through the water in the darkness. Sometimes the effect occurs out in the open ocean over areas hundreds of miles across—a phenomenon known as milky seas. This effect has been observed by both ancient mariners and documented by modern satellite photographs. A third form occurs when the bacteria colonize parts of squid, fish, or other marine creatures; a very common trait among deep-sea organisms.
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One of the most intriguing fish that makes use of bioluminescence is the anglerfish. These bizarre creatures have organs called illicium protruding from their heads that essentially function as a fishing poles. The tips of these organs are colonized by bioluminescent bacteria, which serve as lures. The glow attracts other fish in the deep, dark waters that find themselves fatally positioned in front of the anglerfish’s enormous, fanged jaws. Interestingly, this bioluminescent trait is only possessed by female anglerfish, which can weigh up to 100 pounds and are typically 100 times larger than the males. Besides luring prey, the female anglerfish’s built-in headlight also lures male partners, who then latch on to the body of the female, living the rest of their lives as parasites!
In some of the deep dark forests of the world, the ground glows as you walk down the trail. This is a result of fungi that live in the rotting wood on the forest floor. Unlike most other bioluminescent organisms, the biological purpose of glowing fungus is less understood. Some hypothesize that it is used to attract the insects that eat it and thus help to spread its spores. Others believe it is to repel predators, as the glow is considered a sign of toxicity by many creatures. Bioluminescent fungi are most common in the topics, but they are also quite prevalent in the Appalachian mountains, where they are known locally as ‘foxfire’, and can often be observed on moonless nights in autumn.
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