The Function of Bioluminescence

I am fascinated by bioluminescence in marine animals. In my paper, I want to discuss how bioluminescence was adapted and how it works. I also want to research how it is helpful to different animals. I want to highlight the differences in how barbeled dragonfish and lantersharks use their bioluminescence in different ways. Barbeled dragonfish use it to lure prey, whereas lanternsharks use it to warn predators. So, bioluminescence can be used as a protection mechanism or as a predatory mechanism. I will give a detailed description of the function of bioluminescence in both barbeled dragonfish and lantersharks.

How bioluminescence was adapted

A chemical chain of reactions within a living organism produces a light referred to as bioluminescence. Many bioluminescent organisms are located mostly in the ocean. The marine bioluminescent comprises of bacteria, jellies, and fish. Bioluminescent micro-organisms that are found on land include fungi and fireflies. It is highly unlikely that there are bioluminescent organisms that are native to freshwater.

Chemistry

For bioluminescence to occur, there must be two chemicals which must be present, and they are luciferin and either photoprotein or luciferase. The compound which produces the light in the three is luciferin. Luciferin is referred to as the substrate in a chemical reaction. The bioluminescent hue (for example green-lanternfish and yellow in fireflies) is because of the sequence of the luciferin molecules (“Bioluminescence” 2012). There are bioluminescent organisms which synthesize (produce) luciferin by themselves. For example, Dinoflagellates which are small marine organisms bioluminesce a blue-green color. Dinoflagellates are one of the types of planktons which cause the ocean surface to sparkle during the night.

            However, there are bioluminescent organisms which do not produce luciferin. They, however, absorb luciferin through other living organisms for example in a symbiotic relationship or as food. For example, there are midshipman fish species that get luciferin from ”seed shrimp” which they consume. There are marine animals for example squid that have bioluminescent bacteria in their systems. The squid and bacteria have what is referred to as a symbiotic association. Luciferase is a type of enzyme. The definition of an enzyme is that it is a catalyst or chemical which interacts with a substrate to effect on a chemical reaction. When luciferase interacts with oxygen-added (oxidation), it results in the production of a byproduct referred to as oxyluciferin. The most important thing is that light is created as a result of the chemical reaction.

            Bioluminescent dinoflagellates emit light by use of a luciferase-luciferin reaction. The luciferase which is usually in dinoflagellates has a relation to chlorophyll which is a green chemical that is generally found in plants. Bioluminescent dinoflagellate environments are not common. They only form in warm-water coves that have narrow openings into the sea. In these bays or coves, bioluminescent dinoflagellates are prevented from escaping. All the coves can be well-lit at night. Majority of bioluminescent reactions involve luciferase and luciferin. However, there are reactions which do not comprise luciferase (or any other enzyme). In these reactions, there is usually the presence of photoprotein which is a chemical. Photoproteins then combine with oxygen and luciferins, but they also need another agent which in most cases is an ion that belongs to the calcium element to produce light.

Photoproteins have just recently been branded, and chemists and biologists are still in the process of learning their strange chemical characteristics. In the early days, photoproteins were normally observed while in crystal jellies gotten from the North America west coast. This photoprotein which is in the form of crystal jellies is known as GFP (green fluorescent protein). However, bioluminescence is not fluorescence because in fluorescence there is no involvement of a chemical reaction which is involved. Stimulating light is only absorbed and then re-emitted in fluorescence. The fluorescing brightness can only be seen when there is stimulating light. For example, ink in highlighter ball-points is fluorescent. Some people say that phosphorescence is almost similar to flourescence the difference is phosphorescent light can emit light for a more extended period. Stickers that glow in the dark are a type of phosphorescent.

Bioluminescent light

How bioluminescent light appears depends a lot on the organism and habitat in that it is found. A lot of marine bioluminescence, for example, is seen in the blue-green part of the light field. In the deep ocean, these colors can easily be seen. A majority of marine animals are only sensitive to green-blue colors. Most marine animals cannot process violet, red, or yellow colors. A lot of land animals show green-blue bioluminescence. There are also those that glow in the yellow spectrum, fireflies included. Quantula striata are the only land snail that is bioluminescent and are found in the tropical areas located in Southeast Asia.

There are not that many organisms that have the capability to glow in more than one color. The ”rail-road” worm can be termed as the most familiar. The railroad worm’s head has a red glow, and the body glow has a green glow. The difference in the glow is because of the different ways in which bioluminescence is expressed. Some organisms continuously emit light. Some fungi species are found in decaying wood and emit a glow that is called Foxfire. However, some organisms use the light from their organs to flash normally for at most 10 seconds. The flashes can be in particular places for example in the dotted parts of a squid. There are flashes which can illuminate the entire body of the organism.

How bioluminescence is useful in different animals

Defensive Adaptations

There are species use luminesce to distract or confuse their attackers. For example, many squid species flash to scare aware predators like fish. The fish will be startled by the light giving the squid a chance to escape quickly. The vampire squid also shows this type of defensive behavior. It lacks ink sacs just like other many squids that live in the deep sea. To defend itself, the vampire squid expels bioluminescent mucus that is sticky and can confuse, delay or startle predators giving the squid an opportunity to escape.

Counterillumination is a technique which a lot of marine species use. Sharks are one of the many predators that hunt from below. They hunt by looking above where the sun rays cast shadows under the prey. Some animals use counterillumination to protect themselves. The hatchetfish are an example of animals that use counterillumination. The fish have organs that produce light that point downwards (Christopher). They ensure that the light under them is the same as that coming from above. The adjustment of their bioluminescence helps them disguise their shadow, and they become almost invisible to predators that may be looking up.

There are bioluminescent animals for example brittle stars that can detach some of their body parts thereby distracting predators. Hence the predator will follow the brittle star’s glowing arm, and the animals will crawl to the dark. The brittle star will later regrow a new arm. There are animals which can detach their body parts onto other prey to distract predators. Some sea cucumber species can break off their luminescent body parts onto other fish. The sea cucumber will escape when the predator follows the glow on the other fish.

Studies by biologists indicate that there are some whale and shark species which may use defensive bioluminescence for their advantage even if they do not have the capability of being bioluminescent. For example, a sperm whale may live in in the same habitat as bioluminescent plankton though the sperm whale does not feed on the plankton. Fish are predators of the plankton so when the fish approach the plankton, the plankton will glow, and the glow attracts the whale and the whale eats the fish. After their predator is eaten the plankton stop glowing.

There are insect larvae which are nicknamed glow worms that warn predators of their toxicity. Predators such as birds and toads will know that they are not to be consumed because they might cause either death or illness.

Offensive Adaptations

Marine animals may use bioluminescence to search for or lure prey. The anglerfish may be the most famous predator that uses bioluminescence for feeding. An anglerfish has sharp teeth, a huge head, and also an almost fleshy growth on the top of its head which is referred to as a filament. It has a ball at the end of its filament called the esca which the anglerfish lights up when it sees prey approaching. Smaller fish which are usually curious about the light swim towards it to get a closer look. The prey may see the dark jaws of the anglerfish when it is too late.

Other types of fish, for example, the loosejaws which are a type of dragonfish search for prey using bioluminescence. Loosejaws emit red light, but their prey mostly sees blue light. The loosejaws, therefore, have a huge advantage after lighting up their surroundings. They can be able to see their prey whereas the prey is not aware of the danger that lurks near them.

Attraction

Lightning bugs or adult fireflies are bioluminescent. To attract mates for reproduction, they light up. Both female and male fireflies luminesce, however, in North America many of the fireflies that luminesce are male. Their flash patterns signal to female fireflies the species of firefly that they belong to and whether they may be interested in mating at all.

Introduction of Bioluminescence in Marine Animals

Bioluminescence is defined as the process by which a living organism produces and emits light. Bioluminescence is a type of chemiluminescence. It occurs a lot in invertebrates and vertebrates and also in some fungi. Bioluminescence is also present in terrestrial invertebrates and microorganisms. In some animals, this light is bacteriogenic meaning it is produced by organisms that are symbiotic for example vibrio bacteria while in some animals it is autogenic meaning the animals themselves emit the light. Generally, the main chemical reaction in bioluminescence involves a molecule emitting light and, an enzyme called the luciferin and luciferase respectively. The essay below will compare uses of Bioluminesence in Barbeled Dragonfish and Lanternsharks

Barbeled dragonfish

They belong to the stomiidae family which are ray-finned deep sea fish. They are usually quite small despite looking gruseom and they measure from 15cm-26cm. the fish live in deep waters at depths of 5,000 metres.

Lantern sharks

The lantern fish also known as Symbolophorus barnardi is a fish which lives in the deep sea and it name is derived from its capability to produce light.

Locating prey

The light in the deep sea/barbeled dragon fish is produced by a distinct organ called the photophore. It is believed that the fish use this light to attract their prey. The deep sea dragon fish has a big head and mouth which has may sharp fang like teeth. In its chin, it has a big protrusion called a barbel. The barbell has a photphore which produces light. Dragon fish also have photophores on the sides of their bodies.

The barbel producing light is used by the deep sea fish like a fishing lure. By waving it back and forth and flashing it on and off, it is assumed that the dragon fish can use bioluminescence to catch the attention of its next potential meal. When an unsuspecting fish gets very close, the dragon fish uses its powerful jaws to snap it up. The dragon fish’s large teeth helps it grab its prey when it goes hunting in the deep seas dark waters. The dragon fish feeds on crustaceans and small fish and also anything which it can find.

Attracting prey

Tiny organs known as photophores give off the light in a chemical reaction known as bioluminescence. It is the same process which fireflies use. The photophores are found in the underside, tail, and head of the lantern shark. It is believed that the shark uses the light to attract smaller fish which it feeds on.

Camouflage

Lantern shark

The lantern shark has most of its photophores on its underside which it also uses for camouflage. Using a process known as counter illumination, the sharks can eliminate their silhouette making them invisible to predators which are below it (Ed Yong). Counter illumination is a camouflage method that is used by marine animals whereby they produce light thereby matching their surrounding in both wavelength and brightness. It acts as an invisibility cloak. The light which is emitted by the photophores is of constant intensity it has however been hypothesized that the lantern sharks move to different depths during the day to make sure that they match their light to that of the environment. It means that during the day when the light is high, the sharks go deeper in the ocean so that they stay camouflaged. During the night, they will go to more shallow depths so that they can stay cryptic.

Barbeled dragon fish

The photophores which are located on the belly serve as camouflage. The photophores on their bellies are similar to light that streams down from the surface and make the fish invisible from predators which may be facing up. Also since a lot of its prey also produces light, the dragon fish has a special method of making sure that it stays hidden from its predators after it has had a meal. Its stomach walls are black in color to ensure that the lights are covered when it is digesting its meal.

Communication

Lantern sharks

Velvet belly species of lantern shark warns other animals using light. On its back fins, the shark has two spines that are lightened up by a row of photophores which are placed unusually. The spines are three to four metres apart and are clearly visible. It is the perfect distance which can be used to chase off predators while not making the predator aware of the shark’s location.

            Some lantern sharks can also communicate using light. The Etmopterus species of lanternsharks have photophores which are on their flanks while the patterns are different depending on the species. They may perhaps act as a form of identity by which sharks can find it easy to find their own. Use of mathematical techniques which is dependent on the anatomy of fishes, researchers have come to the conclusion that lateral photophore outline on specific lantern fish leanages are distinctive enough to enable identification of specific species. It is normally a valuable trait because many species are usually found mostly in the sea area. It is usually visible in velvet belly lantern sharks which glow that emanates from their flanks on then off. It is usually an optical deception. It is because the photophores normally emit a narrow beam which can be seen from certain points of view only. As the sharks swim, they do so by rotating their bodies left to right turning a steady light streams to what seems as a strobe. It is an advantage in the deep sea where the sharks live in permanent darkness.

Illumination

Barbeled dragon fish

Most marine bioluminescence is usually green to blue. However, there are deep sea barbeled dragon fishes that are in the genera Malacosteus, Pachystomias, and Aristostomias which give off a red glow. The adaptation helps the barbeled dragon fish see red-pigmented targets that are usually invisible in the deep ocean where the water column filters out the red light.

Other uses of Bioluminesence in lantern sharks

a. Glowing genitals.

In some of the shark species, the photophores which are in the genital region helps shark identify opposite sex members. It is useful for procreation in the dark.

b. Identification lights

The distribution and presence of glowing cells on the shark’s sides are unique to the species. It may be used by sharks to identify their fellow species.

c. Visual detterents

Light organs are usually found in the dorsal fin which are behind the transparent dorsal fin spines. The glowing fin spines may visually deter any potential predators.

d. Love handles

Female lantern sharks normally have a light strip on their pectoral fins. It helps males to hold on during copulation. It reduces fumbling around.

Other uses of bioluminescence in barbeled dragon fish

a. Signal a potential mate.

It uses its photophores to signal its fellow mates when it wants to mate.

b. To distract or attract fish that may be below it.

The barbeled dragonfish may use its barbell as a lure. It can wave it back and forth or flash it on and off to attract its next potential meal. If an unsuspecting fish gets closer, the barbeled dragonfish will eat it.

Conclusion

Bioluminescence is important to marine animals for various purposes such as feeding, mating, and scaring off predators. These help the barbeled dragon fish and lantern shark to survive in the sea. Bioluminescence offers an interesting insight into how animals use light for survival.

Works Cited

”Bioluminescence.” National Geographic Society, 9 Oct. 2012, www.nationalgeographic.org/encyclopedia/bioluminescence/.

”Deep-Sea Dragonfish.” Smithsonian Ocean, 18 May 2018, ocean.si.edu/ocean-life/fish/deep-sea-dragonfish.

Christopher. ”Glow In The Dark Sharks.” Exploring Our Oceans, 13 Nov. 2014, moocs.southampton.ac.uk/oceans/2014/10/28/glow-in-the-dark-sharks/.

Knight, J. ”Seep Sea Dragonfish.” Deep Sea Creatures on Sea and Sky, www.seasky.org/deep-sea/dragonfish.html.

Yong, Ed. ”Why Do Glowing Sharks Glow?” National Geographic, 28 July 2015, www.nationalgeographic.com/science/phenomena/2015/07/28/glowing-sharks/.