The term bioluminescence is derived from the Greek roots, bios and lumen, meaning living and light, respectively. It refers to all the light-emitting, living organisms which are mostly the marine organisms, but they also include the terrestrial invertebrates, insects and microorganisms. In addition to being famous, the bioluminescent organisms are amazing in that the smallest of the living beings, the microorganisms, enlighten miles of the oceanic stretches due to the presence of bioluminescent bacteria. It is amazing to see how a glow worm distracts a chasing bat through putting its lights on and off intermittently. A few big animals show only a tiny glow to mimic their being small animals, to attract them as prey. Bioluminescence generates only very little of the thermal radiation; therefore, it is sometimes also known as cold light. The bioluminescence results due to oxidation of luciferin, in the presence of the enzyme luciferase.
1. Glowing Firefly
Glowing firefly, according to the zoological classification belongs to the Lampyridae family. It is a family of insects including over 2,000 species of beetles. The glowing fireflies are Crepuscular animals, which are characterized by their being active during twilight or during the dawn and dusk. They contain a chemical which upon oxidation produces the cold light. The light emits usually from the lower abdomen, and the color of light may be yellow, green or pale red. Marshes and wet woods are their habitat. In some species, both the male and female can fly while in others, the females are flightless and attract the males for mating through their light signals. Some fireflies emit the light intermittently to distract and mislead their nocturnal hunters like bats. Sometimes they are also known as lightning bugs, just as Mark Twain said, ‘the difference between the right word and the almost right word is the difference between lightning and the lightning bug?”
2. Glow Worm
A glow worm like the one zoologically known as Lampyris noctiluca, in spite of having some distinguishing features, is included in the family of fireflies. Charles Darwin, in his book The Voyage of the Beagl wrote, ‘All the fireflies, which I caught here, belonged to the Lampyridae, in which family the English glowworm is included, and the greater number of specimens were of Lampyris occidentals.’ The male glow worms can fly, while the female glow worms are larviforme or, in other words, they do not have wings. The glow worms use their glow to attract their mate. The female glow worms emit yellowish green light from their last three abdominal segments. The glow worms can adjust the light intensity through regulating the oxygen supply to the light-emitting membrane. The females can glow two hours daily for ten consecutive nights and mostly succeed in finding the mate within this period, after which they stop glowing.
3. Bobtail Squid
Bobtail squid, scientifically known as Sepiolida, belongs to the class cephalopoda, the marine non-vertebrates. They are known for their big head and prominent tentacles, hence the name, Cephalopoda from Cephalo, meaning head and poda meaning feet. There are about 100 genera of the squid and cuttlefish, and 63 of them are bioluminescent. Bobtail squid have eight suckered arms and two tentacles. They have symbiosis with the bioluminescent bacteria, Vibrio fischeri, which impart the luminescence to them. The squid feeds the bacteria with its nutrient sugar and amino acids, while the bacteria in return give them the glow to camouflage. The bobtail squid habitats include Pacific Ocean, Indian Ocean, Cape Peninsula and northwestern Hawaiian waters.
4. Stoplight Loosejaws
Belonging to genus Malacosteus, Stoplight Loosejaws are the called loosejaws on account of their widest gape among the fish. Their lower jaw measures one quarter of their body length. Because of their large and wide open jaws, they are also known as rat-trap fish. Loose jaws are bioluminescent and, amazingly, they emit three colors of light: red, green and blue. On account of the red and green lights, these fish are also known as traffic lights. There are three bioluminescent photophores, the light-emitting organs, which emit red light and behind it is situated the tear shaped photophore, which emits green light.
Tomopteris is a tiny marine worm, known for emitting light sparks from its tiny photophores. One of its species, Tomopteris nisseni, is particularly known for emitting yellow light which is a rare phenomenon, as yellow bioluminescence is not common among the marine creatures. Other species of Tomopteris emit unique blue light. The worm is about 3 cm long and is found in the cold waters of the North Atlantic Ocean. Abundance of these organisms on the icebergs impart them the look of luminous and attractive peaks of mountains.
6. Bioluminescent mushrooms
Over 70 species of mushroom emit light. Most known among them are Panellus stipticus, Mycena lux-coeli and Omphalotus olearius. The glowing mushrooms are commonly known as foxfire or fairy fire. In 382 B.C Aristotle mentioned a light which appeared like fire, but unlike fire, it was a cold light. The fungal bioluminescence is usually greenish and is caused by the oxidation of luciferin in the presence of the enzyme luciferase. In Mark Twain’s novel Adventures of Huckleberry Finn, the characters Tom Sawyer and Huckleberry Finn used the foxfire as the source of light to dig a tunnel.
7. The Hatchetfish
The Hatchetfish is found in Atlantic, Pacific and Indian oceans. It is usually 2 to 4 cm in length but the giant Hatchetfish reach up to 12 cm in length. They live from 50 to 1,500 meters depth of the ocean. Like many of their relatives they have the light-giving organs, the photophores, on their silvery abdomen. Their capability to glow and adjust light to match different intensities helps them to camouflage and defend themselves from predators in deep and dark sea. The phenomenon of adjusting their body color to match the surrounding light intensity is known as counter illumination, and is an important self-defense technique for the Hatchetfish.
8. Glowing Jellyfish
Aequorea victoria, commonly known as the crystal jelly, is a bioluminescent fish. It is considered one of the most influential jellyfishes, by dint of a unique proteinous substance which finds use in the treatment of cancer. Roger Y. Tsein and Mart Chalfie, the scientists who discovered GFP, the green fluorescent protein, were awarded the 2008 Nobel Prize in chemistry. GFP is also being used to diagnose Alzheimer’s disease through inducing GFP in the brain cells. This jellyfish is found off the west coast of North America. Jellyfish are comprised of more than 90% water and their bioluminescence creates unique and amazing luminous graphics in the ocean.
9. The Glowing Fungus
The Stiptic Fungus, also known as the luminescent Panellus or the Stiptic fungus, is a common fungus found in almost all the continents. It grows in clusters on the decaying organic matter, mostly on the stumps of oak a birch. Panellus stipticus is a bioluminescent species. The fungus glows on the edges. The fungus is known for its detoxification property. It was first identified in 1879 by the French mycologist Jean Bulliard. The fungus is used to detoxify some environmental pollutants.
10. Glowing Scorpion
Scorpions are the predatory animals, easily identified by their pair of grasping claws, upward curved and segmented tail with a stinger at the end and crawling on its eight feet. Their size falls in the range of 0.9 cm to 20 cm. They are found on all continents except Antarctica. About 20 of the 1,500 species are extremely venomous and can kill a human being. The scorpions glow when exposed to ultraviolet light, which is also known as black light. This characteristic is used to find them in the night. The glow is caused by a fluorescent chemical called beta-carboline, secreted by some organs of the scorpions.
No creature has been kept deprived of self-defense and bioluminescence is in fact an amazing defense mechanism, utilized by smaller organisms to keep the larger organism of prey at a safe distance from them. Although the phenomenon has never been exploited commercially except in case of the jellyfish, prior to the invention the miner’s safety lamp by Sir Humphrey Davy in 1815, the coal miners used fish skins to obtain cold light in the mines. Some fish species like the neon fish, guppy, and angle fish are especially adored by the hobbyists. What the stars are to the sky, the glowing bioluminescent organisms are to the dark and deep oceans.