Bioluminescence,as the name suggests -it is the emission of light duto an biological enzyme,usually emitted by a living organism.

Some living organisms like deepwares squids,fishes,some insects like firefly,etc., can produce light with the help of some kind of chemical reaction through enzymes secreted in their body.

Bioluminescence is most common in living creatures that has an habitat in pitch black darkness.

It is usually seen in deep ocean creatures,but rarely seen on land organisms.

It was discovered that Bioluminescence is even exhibited by some bacteria and fungi.

Scientists have deduced that the enzyme that causes/helps to produce Bioluminescence is called Luciferin,it is said that if this enzyme gets oxidized under suitable conditions,light is emitted.

The amazing part is no heat(very very negligible) is produced.We did not know this phenomenon till researchers found out about this unique and unusual behavior.

Usually whenever bright light is emitted some heat is also emitted along with it.But some living creatures have managed to evolve,creating Bioluminescence without creating harmful heat that may damage their body.

This enzyme luciferin is found in the form of variety of chemicals.This lead to the theory that this Bioluminescence chemical must have been evolved many years ago for different purposes by different organisms.

There are many theories that suggest why and how creatures came to exhibiting Bioluminescence,but there is one prominent explanation that suggests that the organisms must have evolved a way to counteract the harmful chemical reactions of molecular oxygen,in the process light must have been produced and the organisms found it to be useful in many ways.

So there must be a question raised,why are some chemical reactions of oxygen harmful?

It is said that when living organisms intake oxygen,the cells convert oxygen to energy,but in the process some free radicals of oxygen are emitted that affects the growth of cells hence ageing.how does oxygen affect our cells? well we've seen what happens to a strong iron rod when it is exposed to water and oxygen...The same prettymuch happens in organisms in a slow,small scale.

The Bioluminescence color may vary from red,yellow,blue or green.This is basically simple physics of varying wavelengths of light that produces particular color.

The color produced may depend upon the environment of the creature and the purpose for which the organism uses Bioluminescence.

The mechanism how the Bioluminescence is produuced,is through special enzyme called luciferin(which we already know) but these are produced by special cells called photocytes.Hence these animals do not absorb light and then reproduce it,rather they produce light on their own.

This luminescent cells are organised into luminescent tissues(called photophores),that contain special structures over their surface like reflective protrutions,lenses,shutters,etc., for controlling the emission of light.

Most of the Bioluminescence exhibited by the creatures are flashes of light,lasting only for few seconds or milli seconds.Only a few creatures produce continuous light.

It is also discovered that some cratures exhibit Bioluminescence but do not produce their own light.They use the help of bacterias that produce Bioluminescence.They contain these bacterias in special bag like structres,with special mechanisms to turn the light on and off.some examples of this type of Bioluminescent creatures are flashlight fish found in the Philippines and squid such as the Hawaiian bobtail squid.

So now the question is what are the purposes for which organisms exhibit Bioluminescence?

There are many purposes for which Bioluminescence is used,some eminent uses are fro attracting mate/prey.To provide a sudden confusion so that the creature can escape from it's preditor and for communicating within the same species.

Some species use the Bioluminescence intelligently,by having Bioluminescence organ below them so that when they are floating over a preditor,the preditor cannot distinguish the Bioluminescence frm sun light!

There are some fish that hunt or travel in groups, use Bioluminescence to help coordinate the movements of the school.

Deep-sea anglerfish have luminescent lures that attract potential prey within reach of their mouths.

Some insect that live in caves,glow worm,larvaes have glowing tails that attract flying insects into sticky dangling strings that the glow worms use to catch prey.some species of fireflies mimic the mating flashes of other firefly species then,when an unsuspecting fire fly arrives,they attack them and eat them.

But there are also bacteria and fungi,nushrooms that exhibit Bioluminescence,but scientists are unable to determine the actual use for the phenomenon in them.

Bioluminescence is being studied by scientists especially in the biomedical research area,mostly trying to mimic the Bioluminescence and to use them for medical purposes either for diagnostics or for some detection process.