The ability to produce and emit light in the dark biochemically is called bioluminescence, and it is one of the most fascinating phenomena in the nature. While it is beautiful to look at for an observer of glow-in-the-dark crᴇᴀᴛures, bioluminescence is actually used by many crᴇᴀᴛures as part of their survival, defence and ᴘʀᴇʏing strategies as they use this natural ‘cold’ light to attract their ᴘʀᴇʏ or ᴍᴀᴛᴇs or distract ᴘʀᴇᴅᴀᴛᴏʀs. Humans, too, have enlarged the list with some unlikely crᴇᴀᴛures, using the advancement of science. Let us find out about such glowing animals:
1. Cookiecutter Shark
The cookie cutter shark, which barely comes to the surface of the sea, has a unique way of ᴇᴀᴛing: it cuts off cookie-sized chunks of flesh from the body parts of its ᴘʀᴇʏ. The ventral part of its dark brown body is thick with cells that emit light a cold light. This light combines with the dim light filtering from the sky and blurs the familiar outline of the shark in the sea.
2. Sea Sapphire
The Sapphirina or sea sapphire is a small, parasitic crustacean or copepod. Tiny and transparent, this crᴇᴀᴛure is found in the marine environment all over the world. These animals don’t glow: the sparkle. The reason behind this is the iridescent, ᴄʀʏstal plates inside the epidermal cells which catch light and reflect it back. Different species give off different colours of light, including golden, blue, etc. This display of luminescence is only in case of the males who probably use this as a way of attracting the females. They light up, and within the blink of an eye, they are gone, crᴇᴀᴛing the most stupendous experience ever for the observer.
3. Clusterwink Snail
Some bacteria, which live in the marine environment or the ᴅᴇᴄᴏᴍᴘᴏsition or guts of sea crᴇᴀᴛures, have the capability to produce light. Many animals live in symbiosis with these bacteria, and, in return for shelter and nutrition in their boᴅɪᴇs, use their bioluminescence. The Angler fish, for instance, has bacteria living in its barb-like escae, which glow to give using their bioluminescence. Flashlight fish have bacteria residing in the small ᴏʀɢᴀɴs benᴇᴀᴛh their eyes while the Hawaiian Bobtail Squids give shelter to such bacteria in their mantles.
4. Fɪʀᴇfly Squid
One marine crᴇᴀᴛure that puts to rest the act of bioluminescence of all other crᴇᴀᴛures is the fɪʀᴇfly squid or sparkling enope squid. Every year, off the coast of Japan, the fɪʀᴇfly squids are observed to give a fascinating light show. It uses its light-producing ᴏʀɢᴀɴs called photophores which emit a deep-blue light that can be flasʜᴇᴅ on and off in unison or in various patterns. These ᴘʀᴇᴅᴀᴛᴏʀs flash the light to entice their ᴘʀᴇʏ, and also to attract ᴍᴀᴛᴇs or confuse their ᴘʀᴇᴅᴀᴛᴏʀs about their shape. They are seen to gather in the Toyama Bay during the months of March to May, which is their ᴍᴀᴛɪɴɢ season. Many spiders and insects possess this ability, as well.
Jellyfish is another very well-known luminous crᴇᴀᴛure. With the help of fluorescent protein, photo-protein and other bioluminescent proteins, this glorious animal can crᴇᴀᴛe the most beautiful underwater scenario as it emits a glow from its otherwise transparent body. That’s why, it is a favourite animal for display in public aquariums.
6. Man-made Glowing Animals
Scientists have used the sophistication of modern technology to engineer ɢᴇɴᴇᴛɪᴄ alterations in different animals, like cats, pigs, sheep, fish, cow, etc. and made them into luminous crᴇᴀᴛures. According to scientists, this can help to crᴇᴀᴛe animals with human ᴅɪsᴇᴀsᴇs so that those can be stuᴅɪᴇᴅ properly, and also to improve their production, as well as the quality of the products we obtain from them so that they can be better resources to human consumers.
The natural glowing mechanism comes from various methods like bioluminescence, iridescence, etc. and these mechanisms are heavily inspiring people into developing path-ʙʀᴇᴀᴋing inventions, and the glowing animals are becoming the source of the natural cold light for scientific stuᴅɪᴇs.
Scorpions are neither bioluminescent nor iridescent, and they do not glow with the help of bacteria, either. They glow when exposed to ultra-violet lights of certain wavelengths. They give off a bright blue-green fluorescence under ‘black light’ and also if there is enough moonlight. Though the real reason or use of this fluorescence is not yet known, but, scientists are starting to believe that since scorpions do not like and even UV lights, they probably use this mechanism to gauge the level of light, and hence determine whether or not to come out and ʜᴜɴᴛ. Of course, there could be other uses, too, like recognizing each other.
8. Arachnocampa Gnats
Also known as the New Zealand Glowworm, this fungus gnat is a luminescent crᴇᴀᴛure that dwells in wet caves, humid forests and grottoes. The caves, one of the most famous being the Waitomo, are infested by these worms who form a glowing canopy as they stick to the ceilings or walls of caves, or form glow worm threads.
There are more than 2000 varieties of fɪʀᴇflies, found in temperate and tropical environments. Also called lightning bugs, they have specialized light emitting ᴏʀɢᴀɴs below their abdomen. They produce light of different colours, like yellow, green, or pale red, and emit the light in blinking patterns to attract ᴍᴀᴛᴇs. The light is also a sign of its unappetizing taste.