Wonders of Chemistry

Bioluminescence

Bioluminescence is a subtype of chemiluminescence. This means light is emitted by a chemical reaction. In bioluminescence the object emitting the light is a living organism. Bioluminescence is easily confused with flour- or phosphorescence. However, flour- and phosphorescence reemit previously received light. Bioluminescent organisms on the other hand produce light from energy. Usually, bioluminescent light is green or blue. It can be yellow and red as well though. The lighting duration varies from a two second flash to an hour-long glow. The organism emitting light can obtain it through a symbiosis as well as through producing it itself.

Bioluminescence occurs in all realms of nature. However, it is found in marine habitats outside the reach of the sun the most. All kinds of organisms possess the ability to produce light. The most common example for a bioluminescent fish is the anglerfish. Another common example on land is a firefly. Bioluminescence is significantly more useful out of the reach of the sunlight so around 76% of deep-sea organisms take advantage of it. In difference in coastal areas only around 2.5% can produce light. Nevertheless, land living organisms can glow too. Fungi, bacteria, and insects get a lead by using bioluminescence.

Bioluminescence is used for a lot of reasons. Most means of usage are known but some are yet to be discovered. For instance, some benthic organisms light up if touched for no known reason. Most animals however use their light for one of the following causes.

· Hunting

Bioluminescence can be used for hunting in multiple ways. Luring prey is the most obvious reason. Some fish have luminous marks on their body to attract smaller animals. Thinking it is a smaller organism some predators might approach to check in on it. A surprising way is not widespread among fish. In fact, there is only one known species to use it. The deep-sea dragon fish is the only known marine species to perceive red light. The fish emits red light and can see without being seen.

· Hiding

Bioluminescence can also be used for hiding in the deep sea. Some predators swim underneath their prey locating the shadow against the descending sunlight. As a solve for this some organisms use counterillumination. Using the light organs on its bottom the prey mimics the sun rays. This makes it impossible for a hunter to see a shadow.

· Mimicry

Mimicry can be used for both defense and hunting. Either the bioluminescent animal can function as some sort of poisonous animal to scare the attacker off or it can act like prey lure. In cases of animals that use bioluminescence for mating there is one more way. It consists of the hunter acting like a mating ready animal of the prey's kind.

· Defense

In defending bioluminescence is put to most uses. In case bioluminescent plankton is about to be eaten it can flash up to scare the attacker away. Another way of defense is giving away the attacker. By lighting up the attacked organisms give away the attacker to its predators. The third way consists of confusing the attacker. The attacked can just throw off a replaceable part of its body that draws attention by glowing.

· Mating

Bioluminescence can be used for mating too. At dark hours, the animal will light up to tell others of their species it is available for mating.

· Communication

The last thing bioluminescence is used for by organisms of all means is communication. Flashing, running and glowing lights can signal all kinds of things to other organisms of the same species.

As mentioned before bioluminescence is a type of chemiluminescence. Therefore, the glowing light is caused by a chemical reaction. The two main types of bioluminescence have one difference. What they have in common is a molecule called luciferin. Luciferin and oxygen react to oxyluciferin while emitting light. The difference in the reactions is the catalyst. There are two main catalysts. It can either be an enzyme called luciferase or a photoprotein. If the catalyst is the photoprotein normally there is some sort of ion required. This could be a magnesium or a calcium ion. ATP the body's energy preservation can also be needed. The reactions including photoproteins are usually short flashes. Luciferase on the other hand is used for long lighting. With the right enzymes the oxyluciferin can be reverted to luciferin.

Humans have been fascinated by natural light since the dawn of time. Therefore, research in bioluminescence is wide advanced. Humans have also put many aspects of it to their use. In the second world war bioluminescent plankton was already used to detect enemy undersea boats. The first scientific use however was the green fluorescent protein (GFP). This protein was isolated from bioluminescent organisms. The GFP emits fluorescent light under blue and ultraviolet light. GFP can be attached to other enzymes and proteins in the human body. This makes it easy to track their way throughout the human organism. Bioluminescence can also be used for light. Although bioluminescent lamps only last three days at maximum research delves deep into the field. Another way it is used is gene manipulated plants. First successors managed to create glowing tobacco. Not only does this save energy. It also can decrease the brightness of unnecessary bright lamps. Another idea is to make trees glow to make roads safer at night.