Some creatures actually can glow blue, yellow or green in the dark naturally. These glow-in-dark organisms can produce and emit light. This process is called bioluminescence. Most organisms produce light by a chemical reaction of luciferin and oxygen with the help of an enzyme called luciferase. Other organisms have bacteria in them that are responsible for glowing. Now, you might ask why the organisms emit light. They are beautiful and magnificent to watch, but the real reason for these organisms to glow include attracting mates or preys, warding off or warn predators of the toxins they carry, distracting the predators, communicating with their own species or disguise themselves. Most bioluminescent organisms are found in depths of oceans. Here are the ten most popular organisms that glow in the dark.
1. Sea Sparkle
You may have seen the beautiful, eye-catching pictures of ocean shores with blue waves or water during the night around the internet. The blue light is emitted by single-celled micro-organisms called Noctiluca scintillans, marine species of dinoflagellate. They do not always glow as they only agitate to glow when they are disturbed by waves or by any other movements around them. Noctiluca scintillans feed on plankton, fish eggs, bacteria, etc.
Even though they are magnificent to watch, it is said that the presence of sea sparkle may be one of the signs of poor quality of water as Noctiluca scintillans are more visible in areas where there is an increased amount of nitrogen and phosphorous. Also, since they don’t move much and tend to feed on phytoplankton, the excretion and the buildup of a high amount of ammonia can be problematic to the aquatic life.
There are more than 70 species of bioluminescent fungi and the most interesting fact about them is that they glow continuously for days. Pretty amazing. They are mostly found in temperate or tropical climates. Panellus stipticus can light up the dark with its intense beautiful greenish light but not much in daylight. A luminous fungus that grows on rotting wood is called foxfire or glow wood. The reason for the fungus to emit light is not yet known for sure. However, it is thought that fungus emit light to attract insects and arthropods to help disperse its spores or to ward off predators or it might be a by-product of the metabolic process.
Glowworm is a name used for different species of insect larvae. Fungus gnat larvae are the one that is interesting and beautiful to look at. They are found in wet caves, humid forests, rock cavities, etc. The bioluminescent glowworms can emit pale blue-green light and produce a sticky thread-like snare to catch food. The light attracts preys to their sticky thread snare and gets stuck and you can guess what happens next. They glow also to ward off predators. There is a popular attraction of glowworms of Waitomo Glowworm Caves in Waitomo, New Zealand. Inside the cave, you will see a breath-taking sight of glowworms lighting up the caves with its mesmerizing blue-green glow.
Anglerfish are creepy-angry-looking fish with a large mouth full of sharp teeth, ready to pounce on preys. It is said they have been in Earth for about 100 million years. There are about 200 species of anglerfish. They are mostly found in the depths of the gloomy lightless bottom of the Atlantic and Antarctica Ocean. To be precise, they live 2,297-3,281 feet below of the ocean. Total darkness.
They live in an environment where there aren’t any much of light so, you might think it is hard for them to find preys. But this fascinating creature has its own way of hunting. It has a bioluminescent ball close to its mouth attached from its head like a fishing pole. The bioluminescence lures its prey right close to the Anglerfish’s gigantic mouth with sharp translucent teeth. Thanks to its teeth, they can prey on creatures twice their size. Female anglerfish are more carnivorous than the male Anglerfish and are much bigger. Also, only female Anglerfish has the ability of bioluminescence lure.
5. Cookiecutter Sharks
Now, this is an interesting shark which has a unique way of preying with the help of bioluminescence. These sharks are dark brown on top while the undersides are lighter shades of brown. Male Cookiecutter sharks can grow up to 16.5 inches while females can grow up to 22 inches. Despite their small size, cookiecutter sharks are very predatory and can prey on fishes a lot bigger than themselves. To be accurate, these sharks are known to haunt seals, sharks, tuna, whales, seals, dolphins!
They have a unique way of preying with the help of bioluminescence. They have a bioluminescent underside surface that glows appearing to a smaller than they originally are. This draws the attention of others predators looking to feed. As a predator swims towards a cookiecutter shark, it swiftly attacks the larger fish by biting into the meat of the predator. This is done with the help of its sharp teeth and its sucking lips. Then it tears off a lump of cookie-shaped meat and leaving a round hole on its prey.
6. Firefly Squid
Firefly squids (Watasenia scintillans) are one of the most famous species of squid in Japan for its amazing bioluminescence. Firefly Squids glow mesmerizing blue with the help of photophores organs present in their bodies. They have small photophores all over their bodies, and large photophores-that glows brighter- around their eyes and also at the tips of their tentacles. They grow only 3 inches on average. These creatures usually live at around 1200 feet deep in the Western Pacific Ocean.
During nighttime, the firefly squid marches up to the surface to prey. They are thought to use their bioluminescence in various ways. They glow to attract their small fishes to prey on. These brilliant creatures can use their glow to disguise themselves and confuse their predators to eventually escape. They are an attraction for tourists in Japan during the months of March to May, the spawning season of firefly squids. Millions or sometimes billion of them get together to lay their eggs in the waters of the Tomayan Bay of Japan. During these months, they are caught by fishermen illuminating the water with their glow. They create mesmerizing blue glow along the shoreline as well as they get washed up by currents.
Fireflies or lightning bugs are the most well-known bioluminescent organisms. There are about 2,000 species of fireflies which are found in both tropical and temperate climates. Fireflies can emit yellow, green or red light from their lower abdomen. The purpose for their blinking lights is usually to warn predators and attract mates. Some species of female fireflies use bioluminescence to attract male fireflies and to devour them!
Bottles of fireflies were used in coal mines as an illumination alternative to candles (Fordyce, W. 20 July 1973. A History Of Coal, Coke And Coal Fields And The Manufacture Of Iron In The North Of England). Because candles risked of igniting coal dust or flammable gases found in coal mines which can lead to fatal explosions.
Fireflies shed poisonous blood when attacked that is why many predators avoid preying on fireflies. Also, fireflies are very useful medically because they contain chemicals luciferase and luciferin. These are used to inject in diseased cells and to be studied by researchers and scientists. These chemicals are also used in spacecraft to detect life in space. The chemicals are also used in equipment that is used to detect bacterial contamination.
8. Crystal Jellyfish
There are many bioluminescent jellyfish species but two interesting ones are Aequorea Victoria(Crystal Jelly) and Ctenophora(Comb Jellies). Aequorea Victoria is mostly transparent-looking and has a mouth that can expand a great amount when feeding-they can swallow jellies that are more than half their size. Also, they are fragile looking but don’t let that fool you because they drift with ocean current.
Mostly found off the west coast of North America from central California to Vancouver. These jellies have about 100 light-producing organs. Crystal Jellies emit blue light originally but the blue light passes through a green fluorescent protein(GFP) that causes their luminescence to appear green. They only emit bright light when disturbed. Crystal jellies are really important and used to extract GFP and photoprotein called aequorin- responsible for bioluminescence- which are really useful research tools used by scientists for gene-related researches.
9. Comb Jelly
Ctenophores or Comb Jellies are transparent, unique oval-shaped with eight rows of hair called combs which they beat to move around. These comb rows diffract light while moving, causing the eye-catching beauty of rainbow effect. They are naturally carnivorous and can prey on other comb jellies larger than its size.
Comb jellies do not sting like other jellyfish. Another interesting fact about them is that when they are taken out of the water, they break apart. So, if you want to observe it closely, you can scoop it up in a transparent container and observe. Not all comb jellies are bioluminescent but most are. Their blue or green bioluminescence occur when disturbed and can only be seen in the dark.
10. Vampire Squid
Vampire squid is an ancient creature which shares similarities of both squid and octopus. It is not as vicious as its appearance or name may imply/suggest. It does not suck blood to survive. Vampire squid has 8 arms with web-like skin that connects all the arms. When it is threatened, it draws its arms over its head, giving an illusion of drawing a cape over its head and exposing its spines. Also, it has abnormally large red eyes and is black in color (sometimes their eyes may look blue and have a pale red body). Hence, it is called vampire squid.
It is 6 inches on average. Vampire squids are found at about 3,000 feet deep, the oxygen minimum layer of the ocean. It is the deep layer of the ocean where oxygen is at low, where no light penetrates through the water and there isn’t much prey for these vampire squids. The amazing vampire squids are well- adapted to this harsh environment. They have a special kind of blood pigment that helps them to carry a large amount of oxygen. They have long thread-like filaments that they use to collect marine snow that they eat. Marine snow is a mixture of dead bodies, snot, and the waste of animals.
Vampire squid has bioluminescence organs-photophores- all over its body, especially large ones at the tip of its arms. It uses its glow to attract prey or flashes different patterns to confuse predators. When vampire squid does not glow, it appears to be invisible in the deep depths of the ocean. Instead of ink sack that other species of squids have that they release when threatened, vampire squids releases bioluminescence mucus that lights up the water and scares off predators. This creature is truly a mesmerizing, unique ocean creature.