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Light producing organs of fishes

Leena Lakhani Department of Zoology, Government Girls P.G. College, Ujjain, Madhya Pradesh, India Email: [email protected]

Received: 28/03/2019 Revised: 07/04/2019 Accepted: 13/04/2019

Abstract Light produced by living relationship, Luciferase, Luciferin, organisms is known as Bioluminescence. Communication, Attraction, Predators. The light produced by luminescent organs in fishes, depends on luminescent bacteria INTRODUCTION: living on the fish in a symbiotic Bioluminescence is the production and relationship in special cells. However emission of light by a living organism. It is some fishes do produce a chemical that a form of chemiluminescence. reacts with water to produce light. The Bioluminescence occurs widely in bacterial light usually produced as a result marine vertebrates and invertebrates, as of an enzyme luciferase mediated well as in some fungi, microorganisms oxidation reaction in which a molecule including some bioluminescent luciferin changes its shape and emits a bacteria and terrestrial invertebrates such single photon of light in the process. The as fireflies. In some animals, the light is luciferin molecule is a complex molecule produced by symbiotic organisms such and can later be returned to its original as Vibrio bacteria (Randall and Anthony shape through a reduction reaction during 1997). which it gains an amount of energy equivalent to the single photon of light The uses of bioluminescence by animals and fish can control the amount of light include counter illumination camouflage, emitted by controlling the blood flow, and mimicry of other animals, for example to hence the oxygen supply, to the cells lure prey, and signaling to other containing the bacteria. In symbiosis ,the individuals of the same species, such as to bacteria are nourished with readily available food sources for growth, and at attract mates. In the laboratory, luciferase- the same time the host utilizes the adapted based systems are used in genetic illumination for communication, preying engineering and for biomedical research. for food, and attracting mates, to Other researchers are investigating the masquerade itself from predators. Keywords: Bioluminescence, possibility of using bioluminescent Luminescent bacteria, Symbiotic systems for street and decorative lighting,

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International Journal of Global Science Research ISSN: 2348-8344 (Online) Vol. 6, Issue. 1, April 2019, pp. 946-952 DOI: 10.26540/ijgsr.v6.i1.2019.122 Available Online at www.ijgsr.com © Copyright 2014 | ijgsr.com | All Rights Reserved and a bioluminescent plant has been Characteristics created (Randall and Anthony, 1997). Many deep-sea fishes are blind relying on their other senses;those that aren't blind Deep in the ocean, where sunlight can no have large and sensitive eyes that can longer penetrate, lies an incredible world use bioluminescent light. These eyes can of darkness. The creatures here have be as much as 100 times more sensitive to evolved their own ways of dealing with the light than human eyes. Also, to avoid darkness. Through a process known as predation, many species are dark to blend bioluminescence; they have developed the in with their environment (Trujillo and ability to use chemicals within their bodies Harold, 2011) to produce light. Bioluminescence is Many deep-sea fish are bioluminescent, mainly a marine phenomenon, it is not with extremely large eyes adapted to the found in fresh water. On land it, is only dark. Bioluminescent organisms are seen in few species of insects and fungi. It capable of producing light biologically is the ocean where this unique ability through the agitation of molecules of achieves its highest form. luciferin, which then produce light. This Bioluminescence occurs when certain process must be done in the presence of chemicals are mixed together. Most of the oxygen. These organisms are common in light created by marine organisms is blue the mesopelagic region and below (200m green in colour. This is because blue light and below). More than 50% of deep-sea travels best in water, and because most fish as well as some species of shrimp and marine organisms are sensitive to blue squid are capable of bioluminescence. light. A notable exception is the About 80% of these organisms have Malacosteid family of fishes, also known photophores – light producing glandular as Loosejaws. These fishes can produce cells that contain luminous bacteria red light and can see it when others can bordered by dark colourings. Some of not. This gives them an advantage by these photophores contain lenses, much allowing them to see their prey while like those in the eyes of humans, which without making their presence known. can intensify or lessen the emanation of Marine creatures produce light with light. The ability to produce light only special organs called photophores. At least requires 1% of the organism's energy and two chemicals are required to produce has many purposes: It is used to search for bioluminescence. The first is known as food and attract prey, like the anglerfish; luciferin. This is the chemical that actually claim territory through patrol; creates the light. The second chemical is communicate and find a mate; and distract called luciferase and is the substance that or temporarily blind predators to escape. actually canalizes the chemical reaction. Also, in the mesopelagic where some light When these chemicals are mixed together still penetrates, some organisms in the presence of oxygen, light is camouflage themselves from predators produced. A by-product of this process is below them by illuminating their bellies to an inert substance called oxyluciferen. match the color and intensity of light from Deep-sea organisms generally inhabit above so that no shadow is cast. This tactic bathypelagic (1000-4000m deep) and is known as counter illumination (Ryan abyssopelagic (4000m-6000m deep) zones. 2007). However characteristics of deep sea Mesopelagic fish organisms, such as bioluminescence can be Mesopelagic fish usually lack defensive seen in the mesopelagic (200m-1000m spines, and use colour deep) zones as well (Randall and Anthony to camouflage themselves from other 1997).

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International Journal of Global Science Research ISSN: 2348-8344 (Online) Vol. 6, Issue. 1, April 2019, pp. 946-952 DOI: 10.26540/ijgsr.v6.i1.2019.122 Available Online at www.ijgsr.com © Copyright 2014 | ijgsr.com | All Rights Reserved fish. Ambush predators are dark, black or animals within its own red. Since the longer, red, wavelengths of tissue. Luminescence of light do not reach the deep sea, red many fishes belongs to this effectively functions the same as black. class. Migratory forms use counter ii. Extracellular shaded silvery colours. On their bellies, luminescence: In this type they often display photophores producing light is produced by low grade light. For a predator from discharge of luminous below, looking upwards, secretion. E.g.: Ceratias. this bioluminescence camouflages the Structure of light organ silhouette of the fish. However, some of The possession of light producing organs these predators have yellow lenses that is quite common in fish particularly, but filter the (red deficient) ambient light, not only, in those species that live in leaving the bioluminescence visible deeper waters. Forty-five percent of fish (Munz, 1976; Kenaley, 2007) that live at depths below 300 meters and The stoplight loosejaw is also one of the 75% of all bathypelagic fish have some few fishes that produce red light emitting organs. The light glands of bioluminescence. As most of their prey different fish species show quite a wide cannot perceive red light, this allows it to variety in complexity. The simplest are hunt with an essentially invisible beam of just a few cells embedded in the skin. The light (Ryan, 2007). complex systems involve a light producing Bathypelagic fish gland, a reflecting layer behind the light Bathypelagic fish are sedentary, adapted to source (black or silver), a color filter and a outputting minimum energy in a habitat lens. The positioning of the light organs is with very little food or available energy, also highly variable between species. not even sunlight, only Important structural parts of light organs bioluminescence. The humpback are as follows: anglerfish is a bathypelagic ambush Light glands predator, which attracts prey with a Photocytes (light glands) are the light bioluminescent lure (Moyle and Cech, producing cells. They are glandular in 2004). The pelican eel uses its mouth like nature as they secrete luciferin and a net by opening its large mouth and luciferase, the two essential components of swimming at its prey. It has a luminescent light production. Mainly two types of organ at the tip of its tail to attract prey photocytes are observed. They are (Iqbal, 2008). photocyte A and photocyte B. Photocyte Types of bioluminescence A occupies the inner and deeper region of Luminescence of fishes is of two types: photophore. While photocyte B occurs in 1. Luminescence that results from the the outer region of photophore. Both have presence of luminous bacteria living on the secretory characteristics. fish in a symbiotic relationship. For example: Leognathidae, Acropomatidae, Lens Monocentridae and Gadidae. Lenses of light organs are structures 2. Luminescence that arises from self- containing a mass or plate of clear tissue luminous cells on the fish. It may be of and are so called because of their two types: resemblance to ocular lenses. The tissue is i. Intracellular epithelial and the cells have a luminescence: In this type homogeneous cytoplasm devoid of light is generated by the inclusions. Presumably these lenses

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International Journal of Global Science Research ISSN: 2348-8344 (Online) Vol. 6, Issue. 1, April 2019, pp. 946-952 DOI: 10.26540/ijgsr.v6.i1.2019.122 Available Online at www.ijgsr.com © Copyright 2014 | ijgsr.com | All Rights Reserved function is in concentrating the light beam. Light organ in various species of fishes This however, requires that the refractive and their role index of the lens be greater than that of the surrounding. Many species of fish have lights on the lower parts of their bodies. Scientists believe they use these lights to prevent their bodies becoming silhouetted against the surface. By having lights on their underside fish can break up the pattern of their body and effectively hide in the haze. Lights along the sides of the body are more likely to be for communicating with other members of their own species, either whilst shoaling, or to attract potential mates. In other fish, such as the well- known angler fish the light organs seem designed to attract prey. Nearly all angler fish possess luminous baits. The same applies to other types of fish with lights near their jaws or at the ends of fins or barbels. Malacocephalus laevis has light Source Trujillo Alan et.al.2 producing bacteria in a gland near its anus, when it is disturbed it can eject some of Reflector these bacteria into the water through its The wall of light organ (photophore) often anus, the sudden appearance of this contains a reflector together with a backing luminescent mass would easily of dark pigment. The reflectors consist of disorientate a predator. It is possible that elongated connective tissue cells. The cells fish with lights distant from the center of contain platelets of guanine, arranged in their body, such as on or near their tail, regular piles above one another, parallel to may use these lights to disorientate the surface of the reflector. The shape of predators. Some fish can actually produce the reflector and the orientation of its a beam of light, and such a beam would component platelets play a very important obviously help them find prey. Many role in controlling the direction and spread bathypelagic fish with light producing of the light beam. organs also have addition light organs that Pigment mentle shine into their own eyes; scientists Pigment mentle often lying underneath the believe that this may work to accustom light organ contains black melanophores. their eyes to a certain level of light so that Dark pigmented mentle probably ensures when they turn on their main lights they do that no light diffuses inward into the tissue not blind themselves. Most luminous fish of the fish. They occur even when there is are teleost but there are some luminous a well-organized reflector presumably sharks as well such as Euprotomicrus mopping up light transmitted through the bispinatus, which is also the smallest shark latter. Besides, pigment hulls also play in the world. Some examples of important role in controlling the emission bioluminescent fish are: Isistius of light in preferred direction. The Color brasiliensis which has thousands of small filters are used to adjust the overall color luminescent organs on its belly; composition of an image (Haygood, 2008). Anamalops koptroton and Photoblepheron

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International Journal of Global Science Research ISSN: 2348-8344 (Online) Vol. 6, Issue. 1, April 2019, pp. 946-952 DOI: 10.26540/ijgsr.v6.i1.2019.122 Available Online at www.ijgsr.com © Copyright 2014 | ijgsr.com | All Rights Reserved palpebratus which are coastal; Giganticus 2008; Sparks et al., 2014; vanhoffeni and Dolopichthys niger which http://en.wikipedia.org/w/index.php) are both deep-sea angler fish (Haygood,

Location of light organs on fish body

S. No. Location of light organ Genus name Picture

1 Ventral musculature Acropoma

2 Within abdomen Apogon

3 Entire body surface Idiacanthus

4 Lower surface of the body Etmopterus

5 Beneath the eyes Astronesthes

6 On the tongue Neoscopelus

7 On the tail Saccopharynx

8 On the tentacle Linophryne

9 On the dorsal fin rays Ceratias

10 On the lower jaw Monocentris

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CONCLUSION: typically neurons, that have been Bioluminescence is the production and genetically modified to express light- emission of light by a living organism. It is sensitive ion channels, and also a form of chemiluminescence. Bioluminescence occurs widely in see biophoton, a photon of non-thermal marine vertebrates and invertebrates, as origin in the visible and ultraviolet well as in some fungi, microorganisms spectrum emitted from a biological system. including some bioluminescent bacteria and terrestrial invertebrates such as fireflies. In some animals, the light is REFERENCES: produced by symbiotic organisms such Randall David J. and Anthony Peter as Vibrio bacteria. Farrell. (1997) Deep-sea Fishes. San Diego: Academic, pp.196- 225. ISBN 978- The uses of bioluminescence by animals 0123504401. included camouflage, mimicry of other animals, and signaling to other individuals Trujillo Alan P. and Harold VThurman. (2011) Essentials of Oceanography 10th of the same species, such as to attract ed. Boston: Prentice mates. In the laboratory, luciferase-based Hall, pp.415. ISBN 978-0321668127. systems are used in genetic engineering and for biomedical research. Other Ryan P. (2007) Deep-sea creatures: The researchers are investigating the possibility mesopelagic zone" Te Ara - the Encyclopaedia of New Zealand, Updated of using bioluminescent systems for street 21 September 2007. and decorative lighting, and a bioluminescent plant has been created. Munz WRA. (1976) On yellow lenses in Bioluminescent organisms are a target for mesopelagic animals", Marine Biological many areas of research. Luciferase systems Association of the UK, 56, pp.963–976. are widely used in genetic Kenaley C. P. (2007) Evision of the engineering as reporter genes, each Stoplight Loosejaw Genus producing a different color by Malacosteus (Teleost: Stomiidae: fluorescence, and for biomedical research Malacosteinae), with Description of a New Species from the Temperate Southern using bioluminescence imaging. For Hemisphere and Indian Ocean". Copeia, 4, example, the firefly luciferase gene was pp. 886–900. Doi: 10.1643/0045- used as early as 1986 for research using 8517[886:ROTSLG]2.0.CO;2. transgenic tobacco plants. Vibrio bacteria symbiose with marine invertebrates such Moyle P. B. and Cech J. J. (2004) Fishes, an Introduction to Ichthyology. 5th Ed, as the Hawaiian bobtail squid (Euprymna Benjamin Cummings. ISBN 978-0-13- scolopes), are key experimental models for 100847-2. bioluminescence. Bioluminescent activated destruction is an experimental Iqbal M. M. (2008) Special organs light, cancer treatment. See also bioluminescence, electric organs in fish, Sylhet Agricultural University, Dhaka, optogenetics which involves the use of Bangladesh. light to control cells in living tissue,

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Haygood (2008) M. G. Light organ symbiosis in fishes, 19(4), pp.191-216.

Haddock Steven H.D., Moline Mark A., and Case James F. (2010) Bioluminescence in the Sea, Annual Review of Marine Science 2, pp. 443–493.

Sparks John S., Schelly Robert C., Smith W., Leo Davis, Matthew P., Tchernov Dan, Pieribone Vincent A.and Gruber David F. (2014)The Covert World of Fish Biofluorescence: A Phylogenetically Widespread and Phenotypically Variable Phenomenon, 9 (1). http://en.wikipedia.org/w/index.php

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