What is it
Bioluminescence is the production and emission of light within a living organism in the form of chemiluminescence.
Bioluminescence Occurs in:
- Marine vertebrates/invertebrates
- Microorganisms, such as fungi and bacteria
- Terrestrial arthropods(invertebrate and exoskeleton animal), such as fireflies
The chemical reaction that results in bioluminescence requires two unique chemicals: luciferin and either luciferase or photoprotein. Luciferin is the compound that actually produces light. In a chemical reaction, luciferin is called the substrate. The bioluminescent color is a result of the arrangement of luciferin molecules.
Luciferase is an enzyme. An enzyme is a chemical (called a catalyst) that interacts with a substrate to affect the rate of a chemical reaction. The interaction of the luciferase with oxidized (oxygen-added) luciferin creates a byproduct, called oxyluciferin.
Most bioluminescent reactions involve luciferin and luciferase. Some reactions, however, do not involve an enzyme (luciferase). These reactions involve a chemical called a photoprotein. Photoproteins combine with luciferins and oxygen but need another agent, often an ion of the element calcium, to produce light.
Photoproteins were only recently identified, and biologists and chemists are still studying their unusual chemical properties. Photoproteins were first studied in bioluminescent crystal jellies found off the west coast of North America. The photoprotein in crystal jellies is called “green fluorescent protein” or GFP.
Bioluminescence is not the same thing as fluorescence. Florescence does not involve a chemical reaction. In fluorescence, a stimulating light is absorbed and re-emitted. The fluorescing light is only visible in the presence of the stimulating light. The ink used in highlighter pens ✏️ is fluorescent. Phosphorescence is similar to fluorescence, except the phosphorescent light is able to re-emit light for much longer periods of time. Glow-in-the-dark stickers 💯 are phosphorescent.
In some animals, the light is autogenic, produced by the animals themselves; in others, it is bacteriogenic, produced by symbiotic bacteria.
Some bioluminescent organisms produce (synthesize) luciferin on their own. Dinoflagellates, for instance, bioluminescent in a bluish-green color. Bioluminescent dinoflagellates are a type of plankton — tiny marine organisms that can sometimes cause the surface of the ocean to sparkle at night.
Some bioluminescent organisms do not synthesize luciferin. Instead, they absorb it through other organisms, either as food or in a symbiotic relationship. Some species of midshipman fish, for instance, obtain luciferin through the “seed shrimp” they consume. Many marine animals, such as squid, house bioluminescent bacteria in their light organs. The bacteria and squid have a symbiotic relationship.
What Color Is Bioluminescence?
The appearance of bioluminescent light varies greatly, depending on the habitat and organism in which it is found.
Light travels in waves of different shapes — known as wavelengths — which determine the color of the light. Light travels in waves of different shapes — known as wavelengths — which determine the color of the light. Wavelengths traveling through our eyes are translated into colors by the brain. Our eyes are able to see wavelengths from 400–800nm that travel through the air, known as the visible light spectrum. However light travels differently underwater because longer wavelengths can’t travel as far.
Most marine bioluminescence is in the form of blue-green light. This is because these colors are shorter wavelengths of light, which can travel through (and thus be seen) in both shallow and deep water.
Light traveling from the sun of longer wavelengths — such as red light — doesn’t reach the deep sea. This is why many deep-sea animals are red: it’s effectively the same as being invisible. Moreover, because a certain wavelength of light is not present, many deep-water animals have lost the ability to see it all together.
Most land organisms also exhibit blue-green bioluminescence. However, many glow in the yellow spectrum, including fireflies and the only known land snail to be bioluminescent, Quantula striata, native to the tropics of Southeast Asia.
Why do animals light up
The uses of bioluminescence by animals include counter-illumination camouflage, mimicry of other animals to lure prey, and communicating with other individuals of the same species, and attracting mates.
Counter-illumination camouflage
Many marine species use a technique called counterillumination to protect themselves. Many predators, such as sharks, hunt from below. They look above, where sunlight creates shadows beneath prey. Counterillumination is a type of camouflage against this predatory behavior.
Hatchetfish use counterillumination. Hatchetfish have light-producing organs that point downward. They adjust the amount of light coming from their undersides to match the light coming from above. By adjusting their bioluminescence, they disguise their shadows and become virtually invisible to predators looking up.
Mimicry
Bioluminescence is used by a variety of animals to mimic other species. Many species of deep-sea fish such as the anglerfish and dragonfish make use of aggressive mimicry to attract prey. They have an appendage on their heads called an esca that contains bioluminescent bacteria able to produce a long-lasting glow that the fish can control. The glowing esca is dangled or waved about to lure small animals to within striking distance of the fish.
Female Photuris fireflies sometimes mimic the light pattern of another firefly, Photinus, to attract its males as prey. In this way, they obtain both food and the defensive chemicals named lucibufagins, which Photuris cannot synthesize.
Communicating
Communication in the form of quorum sensing plays a role in the regulation of luminescence in many species of bacteria. Small extracellularly secreted molecules stimulate the bacteria to turn on genes for light production when cell density, measured by the concentration of the secreted molecules, is high.
Pyrosomes are colonial tunicates and each zooid has a pair of luminescent organs on either side of the inlet siphon. When stimulated by light, these turn on and off, causing rhythmic flashing. No neural pathway runs between the zooids, but each response to the light produced by other individuals, and even to light from other nearby colonies. Communication by light emission between the zooids enables coordination of colony effort, for example in swimming where each zooid provides part of the propulsive force.
Attracting
Adult fireflies, also called lightning bugs, are bioluminescent. They light up to attract mates. Although both male and female fireflies can luminesce, in North America most flashing fireflies are male. The pattern of their flashes tells nearby females what species of firefly they are and that they’re interested in mating.
Potential Future
Biology and medicine
Bioluminescent organisms are a target for many areas of research. Luciferase systems are widely used in genetic engineering as reporter genes, each producing a different color by fluorescence, and for biomedical research using bioluminescence imaging. For example, the firefly luciferase gene was used as early as 1986 for research using transgenic tobacco plants.
BioLuminescence Activated Destruction of cancer is an experimental cancer treatment. This firefly technique may add a further layer of depth to photodynamic therapy, an effective treatment that uses bursts of light to attack tumors that sit near the skin’s surface or on the lining of internal organs. As part of the therapy, cancer cells are treated with a photosensitizer and then exposed to lasers or another external beam. The light triggers the production of active oxygen species that can destroy cancer cells.
Light production
The structures of photophores, the light-producing organs in bioluminescent organisms, are being investigated by industrial designers. Engineered bioluminescence could perhaps one day be used to reduce the need for street lighting, or for decorative purposes if it becomes possible to produce light that is both bright enough and can be sustained for long periods at a workable price.
The Glowing Plant project is a project about a small leafy plant that will be made to glow in the dark using synthetic-biology techniques. Researchers seek to engineer the thale cress Arabidopsis thaliana to emit weak, green-blue light by endowing it with genetic circuitry from fireflies.
An iGEM team from Cambridge (England) has started to address the problem that luciferin is consumed in the light-producing reaction by developing a genetic biotechnology part that codes for a luciferin regenerating enzyme from the North American firefly.
In 2016, Glowee, a French company started selling bioluminescent lights for shop fronts and street signs, for use between 1 and 7 in the morning when the law forbids the use of electricity for this purpose.
Key takeaways 🔑
- Bioluminescence is the result of the chemical reaction between luciferin and either luciferase or photoprotein, then emitting light.
- Bioluminescence is used by animals to adapt or take advantage of the surrounding environment.
- Bioluminescence is starting to be adapted as light production and
I’m Louis, someone super passionate about technology and about trying to solve problems in the world. If you enjoyed the article, feel free to reach out to me on Linkedin or through email at louiszhu0210@gmail.com
Thank you very much for reading!!!
