You’re sitting by a fire, on a summer night, and suddenly pinpoints of yellow light keep appearing and disappearing all around you. It’s fascinating, the firefly ball taking place before your very eyes. Without realizing it, you’re witnessing a fascinating biochemical phenomenon: bioluminescence.
This is the production and emission of light by a living organism. Such light is generally the result of an interaction between a “light-bearing” protein, luciferin, and an enzyme, luciferase (from the Latin lux, “light,” and ferre, “to bear”). The meeting of the two provokes a reaction that emits a “cold” blue- or green-colored light.
Apart from the famous firefly, which emits light to attract its partner, there are few terrestrial bioluminescent organisms. The phenomenon occurs mostly in the marine world, where it was first developed by bacteria as a tool for communication.
This light “show” is a real advantage for the survival of those species that use it. Let’s look at some classic cases.
Signaling an intruder
The dinoflagellates Noctiluca scintillans, microscopic algae that are part of plankton, use bioluminescence to protect themselves. When a predator approaches, say a shrimp, the dinoflagellates produce a bluish light. That alarm signal is noticed by a second predator, which happens to be partial to shrimp, and which will then be alerted to the presence of its prey. It acts like a true alarm system! The distress signals of a considerable number of these microscopic beings produce majestic waves of light.
The anglerfish, commonly called the “lantern fish,” lives in abysses. On its head it has a fleshy growth that lights up thanks to the bioluminescent bacteria that inhabit it. Located just above the mouth, this light-producing lure attracts curious fish – which the anglerfish quickly gobbles up!
Luring a predator
More than 65 species of ophiuroids (brittle star) are bioluminescent, a feature they use to keep predators at bay. Related to starfish, this animal has the ability to detach one of its arms, which will light up when an assailant – a crab or a fish, for example – makes contact. The luminous limb will draw the predator in a direction away from the rest of the star’s dark body. Once ingested, it will continue to shine in the belly of the predator, which will in turn be more visible to the eyes of its own predators!
Use by man
Bioluminescence is already used in medical research laboratories to mark cells or molecules. Its potential in day-to-day life is being actively explored. In the future we could see lamps or television screens making use of bioluminescent bacteria, and even see towns lit up by plants that have had bioluminescence genes introduced into them.
Will we one day live in a landscape worthy of the moon Pandora?