Bioluminescence

**Bioluminescence** is how living things produce light. Often this is done by symbiosis. The larger organism contains, often in a special organ, microorganisms which make the light. Eukaryote protists have special organelles, and some bacteria also produce light. 
Bioluminescence is the result of chemical processes, where the energy produced is released as visible light. 

Bioluminescence has appeared many times during evolution. The capacity to produce light is an extension of normal metabolism: all chemical reactions produce a few photons. Visible light is produced when the photon production increases. In the case of bacteria, the original function of the reaction was probably to detoxify excessive oxygen.

ATP (adenosine tri-phosphate), the biological energy source, reacts with **luciferin** with the aid of the enzyme **luciferase** to yield an intermediate complex. This complex combines with oxygen to produce a highly chemiluminescent (brightly shining) compound.

## The oceans 
Bioluminescence is mainly a marine phenomenon.
:"It is the predominant source of light in the largest fraction of the habitable volume of the earth, the deep ocean. In contrast, bioluminescence is essentially absent (with a few exceptions) in fresh water, even in Lake Baikal".

Bioluminescence is found in the sea at all levels.: planktonic, pelagic and benthic organisms. Some planktonic groups, such as dinoflagellates and ctenophores (comb jellies) use it in most species. Most deep-sea marine life use bioluminescence in one form or another. Usually, marine light-emission belongs in the blue and green light spectrum, the wavelengths that can transmit through seawater most easily.

## Functions of bioluminescence 
### Counterillumination camouflage 
In some squid species bacterial bioluminescence is used for counterillumination so  the animal matches the overhead environmental light seen from below. In these animals, light organs control the contrast of this illumination to create optiminal matching.

The structure of photophores, the light producing organs in bioluminescent organisms, are being investigated by industrial designers.

## Bioluminescent organisms 
This is a list of organisms that have visible bioluminescence:

### Terrestrial organisms 
Animals:
* Arthropods
** fireflies
** click beetles
** glow worms
*** railroad worms
** certain mycetophilid flies
** certain centipedes, such as *Geophilus carpophagus*.
** certain millipedes such as *Motyxia*.
* a terrestrial mollusc (a tropical land snail)
** *Quantula striata*
* Annelids
* Fungi – A total of 71 species are bioluminescent, including species of *Armillaria*, *Omphalotus*, *Mycena*, *Gerronema*, *Pleurotus*.
** Mushrooms (see Foxfire)
*** Jack O'Lantern mushroom *(Omphalotus olearius)*
*** ghost fungus *(Omphalotus nidiformis)*
*** Honey mushroom
*** *Panellus stipticus*

### Fish
* Anglerfish
* Cookie-cutter shark
* Flashlight fish
* Gulper eel
* Lanternfish
* Marine hatchetfish
* Midshipman fish
* Pineconefish
* Viperfish

### Fireflies 
Despite their name, fireflies are actually beetles which use an enzymatic reaction involving a chemical compound called **luciferin** to produce their typical greenish flashing light. As well as possibly warning predators about their toxicity, it is thought the main purpose of their flashing abdomen is to attract mates.

### Marine invertebrates 
* many Cnidaria
** Sea pens
** corals
** *Aequorea victoria*, a jellyfish
* certain Ctenophores or "comb jellies"
* certain echinoderms (e.g. Ophiurida)
* certain crustacea
** ostracods
** copepods
** krill
* two species of chaetognaths
* certain molluscs
** certain clams and other bivalves
** certain nudibranchs, sea slugs
** Octopods
*** Bolitaenidae
** order Teuthida
*** Colossal squid
*** Mastigoteuthidae
*** Sepiolidae
*** Sparkling Enope squid
*** Vampire squid

### Microorganisms
* Dinoflagellates (e.g. *Noctiluca scintillans*, *Pyrodimium bahamense*).
* Vibrionaceae (e.g. *Vibrio fischeri*, *Vibrio harveyi*, *Vibrio phosphoreum*)
* Members of the marine bacterial family Shewanellaceae, *Shewanella hanedai* and *Shewanella woodyi* are bioluminescent.

## References
## Other websites 
* Bioluminescence web page
* Lights Alive! at San Diego Natural History Museum