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Bioluminescence is the production and emission of light by a living organism. Its name is a hybrid word, originating from the Greek bios for "living" and theLatin lumen "light". Bioluminescence is a naturally occurring form of chemiluminescence where energy is released by a chemical reaction in the form of light emission. Fireflies, anglerfish, and other creatures produce the chemicals luciferin (a pigment) and luciferase (an enzyme).[1] The luciferin reacts with oxygento create light. The luciferase acts as a catalyst to speed up the reaction, which is sometimes mediated by cofactors such as calcium ions or ATP. The chemical reaction can occur either inside or outside the cell. In bacteria, the expression of genes related to bioluminescence is controlled by an operon called the Lux operon.[2]

Bioluminescence occurs in marine vertebrates and invertebrates, as well as microorganisms and terrestrial animals. Symbiotic organisms carried within larger organisms are also known to bioluminesce.

[edit]Characteristics

Bioluminescence is a form of luminescence, or "cold light" emission; less than 20% of the light generates thermal radiation. It should not be confused withfluorescence, phosphorescence or refraction of light.

Ninety percent of deep-sea marine life are estimated to produce bioluminescence in one form or another. Most marine light-emission belongs in the blue and green light spectrum, the wavelengths that can transmit through the seawater most easily. However, certain loose-jawed fishes emit red and infrared light and the genus Tomopteris emits yellow bioluminescence.

Non-marine bioluminescence is less widely distributed, but a larger variety in colours is seen. The two best-known forms of land bioluminescence are fireflies and glow worms. Other insects, insectlarvae, annelids, arachnids and even species of fungi have been noted to possess bioluminescent abilities.

Some forms of bioluminescence are brighter (or only exist) at night, following a circadian rhythm.

[edit]Adaptations for bioluminescence

There are five main theories for bioluminescent traits:

[edit]Counterillumination camouflage

Further information: Camouflage

In some squid species bacterial bioluminescence is used for counterillumination so the animal matches the overhead environmental light seen from below.[3] In these animals, photoreceptive vesicles have been found that control the contrast of this illumination to create optimal matching.[3] Usually these light organs are separate from the tissue containing the bioluminescent bacteria. However, in one species Euprymna scolopes these bacteria make up an integral component of the animal's light organ.[4]

[edit]Attraction


 

Firefly larva

Bioluminescence is used as a lure to attract prey by several deep sea fish such as the anglerfish. A dangling appendage that extends from the head of the fish attracts small animals to within striking distance of the fish. Some fish, however, use a non-bioluminescent lure.

The cookiecutter shark uses bioluminescence for camouflage, but a small patch on its underbelly remains dark and appears as a small fish to large predatory fish like tuna and mackerel swimming beneath it. When these fish try to consume the "small fish", they are bitten by the shark, which gouges out small circular "cookie cutter" shaped chunks of flesh from its hosts.

Dinoflagellates have an interesting twist on this mechanism. When a predator of plankton is sensed through motion in the water, the dinoflagellate luminesces. This in turn attracts even larger predators which will consume the would-be predator of the dinoflagellate.

The attraction of mates is another proposed mechanism of bioluminescent action. This is seen actively in fireflies, which use periodic flashing in their abdomens to attract mates in the mating season. In the marine environment this has only been well documented in certain small crustaceans calledostracod. It has been suggested that pheromones may be used for long-distance communication, and bioluminescence used at close range to "home in" on the target.

[edit]Repulsion

Certain squid and small crustaceans use bioluminescent chemical mixtures or bioluminescent bacterial slurries in the same way as many squid use ink. A cloud of luminescence is expelled, confusing or repelling a potential predator while the squid or crustacean escapes to safety. Every species of firefly has larvae that glow to repel predators.

[edit]Communication

Communication between bacteria (quorum sensing) plays a role in the regulation of luminesence in many bacterial species. Using small extracellularly secreted molecules, they are able to adapt their behavior to only turn on genes for light production when they are at high cell densities.

[edit]Illumination

While most marine bioluminescence is green to blue, the Black Dragonfish produces a red glow. This adaptation allows the fish to see red-pigmented prey, which are normally invisible in the deep ocean environment where red light has been filtered out by the water column.[5]

[edit]Biotechnology


 

Artistic rendering of bioluminescentAntarctic krill


 

A bobtail squid, one of many bioluminescent squid – 63 out of 100 genera of cuttlefish and squid contain species with the ability.[6]

Bioluminescent organisms are a target for many areas of research. Luciferase systems are widely used in the field of genetic engineering as reporter genes. Luciferase systems have also been harnessed for biomedical research using bioluminescence imaging.

Vibrio symbiosis with numerous marine invertebrates and fish, namely the Hawaiian Bobtail Squid (Euprymna scolopes), are key experimental models forsymbiosis, quorum sensing, and bioluminescence.

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

[edit]Proposed applications of engineered bioluminescence

Some proposed applications of engineered bioluminescence include:[7]

Glowing trees to line highways to save government electricity bills

Christmas trees that do not need lights, reducing danger from electrical fires

Agricultural crops and domestic plants that luminesce when they need watering

New methods for detecting bacterial contamination of meats and other foods

Bio-identifiers for escaped convicts and mental patients

Detecting bacterial species in suspicious corpses

Novelty pets that bioluminesce (rabbits, mice, fish etc.)

[edit]Bioluminescent organisms

Omphalotus nidiformis


Example of a bioluminescent species of mushroom...


...glowing with the lights off.


 

Firefly (species unknown) with and without flash.


 

The fungus Panellus stipticus displaying bioluminescence.

All cells produce some form of bioluminescence within the electromagnetic spectrum, but most are neither visible nor noticeable to the naked eye. Every organism's bioluminescence is unique in wavelength, duration, timing and regularity of flashes. Below follows a list of organisms which have been observed to have visible bioluminescence.

[edit]Terrestrial organisms

Animals:

certain arthropods

fireflies

click beetles

glow worms

railroad worms

certain mycetophilid flies

certain centipedes such as Geophilus carpophagus [8]

certain millipedes such as Motyxia [9]

a terrestrial mollusc (a tropical land snail)

Quantula striata

annelids

Fungi:

Mushrooms (see Foxfire)

Jack O'Lantern mushroom (Omphalotus olearius)

ghost fungus (Omphalotus nidiformis)

Honey mushroom

Panellus stipticus

several species of Mycena

[edit]Fish

Anglerfish

Cookie-cutter shark

Flashlight fish

Gulper eel

Lanternfish

Marine hatchetfish

Midshipman fish

Pineconefish

Viperfish

[edit]Marine invertebrates

many cnidarians

Sea pens

coral

Aequorea victoria, a jellyfish

certain Ctenophores or "comb jellies"

certain echinoderms (e.g. Ophiurida)

certain crustaceans

ostracods

copepods

krill

certain chaetognaths

certain molluscs

certain clams, bivalves

certain nudibranchs, sea slugs

Octopus

Bolitaenidae

the order Teuthida

Colossal Squid

Mastigoteuthidae

Sepiolidae

Sparkling Enope Squid

Vampire squid


 

Blue ocean glow caused by myriad tiny organisms, such as Noctiluca.

[edit]Microorganisms

Dinoflagellates

Vibrionaceae (e.g. Vibrio fischeri, Vibrio harveyi, Vibrio phosphoreum)

Members of the marine bacterial family Shewanellaceae, Shewanella hanedai and Shewanella woodyi have also been shown to be bioluminescent

Fungi – A total of 71 species are bioluminescent[10] including species of Armillaria, Omphalotus, Mycena, Gerronema, Pleurotus.


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