Lights On - 10 Fascinating Bioluminescent Creatures

Some people hear the song “You Light Up My Life” (usually sung by Debbie Boone, but also performed by many other artists) and they think of their loved ones. Literalists, however, hear the familiar tune and think of bioluminescent animals like glowworms and fireflies. One can only wonder if the song was actually written by a glowworm or bioluminescent jellyfish for the apple of its eye. The following list details some of the animals that glow, be they far below the sea surface, flying around in the summer, or even the worms and fungi that glow in the pale light of caves. The glow is produced via a variety of chemical reactions with water or air. The creatures use their light for an interesting array of purposes. Some animals, such as the anglerfish, trap prey, and others use their lights as a warning of predators. It works both ways. Let’s take a look at the animals that glow from inside.

The bacteria called Vibrio harveyi floats in the ocean and are mainly thought to reside near the tropics. V. Harveyi are the likely cause of the effect known as the milky sea, the world’s largest bioluminescent area, which is roughly the size of Connecticut. This effect was largely thought as a myth (even mentioned by Jules Verne in 20,000 Leagues Under the Sea) until being verified by scientists in 2005. Perhaps the most unusual aspect of V. Harveyi is that they seem to communicate with each other via a process called quorum-sensing. This process of cell-to-cell communication which regulates gene expression based on population density is produced by the release of an auto inducer. In addition to luminescence, the auto inducer release regulates production of antibiotic and biofilm. Because of the auto inducer production, V. Harveyi are being studied for biotechnological applications that include incorporation into novel antimicrobials. Source

From bacteria, we move to marine plankton called dinoflagellates. Some of these microorganisms glow with bioluminescence when disturbed. Perhaps the most well known example of this light can be found in Mosquito Bay, which is off the coast of the Puerto Rican island of Vieques. The bay, also known as The Bio Bay, has the perfect combination of elements for the dinoflagellates (in this case, the species known as Pyrodinium bahamense) to show off their blue glow. The bay is surrounded by red mangrove trees (whose dead leaves provide needed nutrients for the bay), is relatively free of pollution, and is deep and big enough to stay cool in the daytime. All of these factors create one of nature’s most beautiful spectacles. Granted, these features must stay in balance for the dinoflagellates to continue to provide their eerie light. Source

Lest you think that bioluminescence is just for microorganisms, we will continue to bigger creatures. A good example of this is the firefly squid (Watasenia scintillans) which is found in particular abundance in Toyama Bay off the coast of central Japan. The firefly squid, also known as the sparkling enope squid, has organs called photophores at the end of each tentacle which emit light. This light is used as a siren song for little fish, which the three-inch squid subsequently munches upon. The squid, which generally live 600-1200 feet below the ocean’s surface, is the only cephalopod to develop color vision which may allow them to differentiate between bioluminescent and ambient light. If you’d like to see the firefly squid for yourself, you can take a sightseeing boat from the Japanese port of Namerikawa. Be forewarned, however, the boat leaves at 3AM. Source

Beauty is often something to be admired from afar. As beautiful as jellyfish can be, they can provide a terrible sting if people get too close. Nevertheless, a jellyfish that flows and glows is one of the most beautiful sights that nature provides. The species Aequorea victoria (also known as crystal jelly) produces a series of blue light flashes by releasing calcium, which reacts with the photoprotein aequorin. While crystal jelly emits blue and green light, jellyfish throughout the seas emit a rainbow of colors. A newly discovered jellyfish emits a red glow. Jellyfish become luminescent when they are touched (as well as providing that sting) as a warning to their fellow creatures.  Source

The anglerfish may not look like the friendliest denizen of the seas, but the fish uses bioluminescence to its advantage much like the prettier creatures. There are a wide variety of anglerfish and they can be found in both open water and benthic environments. They also take a multitude of forms, including round and long. All of the species are not very big (the largest grow to 250 mm). They do have a big mouth that snaps upon their prey which swims toward the light that sprouts from a long filament which sprouts from the middle of their forehead. Unlike previous creatures, which emit light by being disturbed, the light that spells the end of many tiny swimmers’ lives is produced by a symbiotic relationship with bacteria. One species of anglerfish that you may have heard of, and even consumed, is the goosefish. The tail of the goosefish has been compared to lobster in terms of taste and texture. Source

If you are not willing to dive deep to see creatures give off an unearthly glow, you are in luck. There are worms that glow called dismalites that can be found in very select places in North America. The larvae of these worms live in stream banks and sandstone caves. Like the anglerfish, dismalites (Orfelia fultoni) use their blue-green light to find food by attracting insects. Once the insects take notice of the light, they fly into a sticky web spun by the worms and are eaten, which may make the worms something other than dismal. These small worms can be found in North Carolina, Tennessee, and Virginia, and were named after the Dismal Canyons in Alabama (where they can also be found). If you are interested in traveling to the southeastern United States to see dismalites, the best time to go is during the summer (May to September). Source

Dismalites are a type of glowworm, but more types of glowworm exist around the globe. Like dismalites, glowworms use their bioluminescence to attract insects (and even some small snails and millipedes) into a web. For this reason, their Latin name is Arachnocampa (which translates indirectly to spider-worm). Perhaps the most well-known glowworm is the Arachnocampa luminoso of New Zealand. In addition to using its light to attract unsuspecting prey, the New Zealand glowworm uses the light to burn off energy. The light is made via a chemical reaction between chemicals emitted by the glowworm and the oxygen in the air. In New Zealand, glowworms survive in caves because they can spin their webs from the cave ceiling. The dark caves are also conducive to the bioluminescent light being seen more easily. Other species of glowworms can be found in dark places in Wales, Tasmania, and Australia. Source

We move from the ocean to the cave to the air in the summer. Fireflies are perhaps the most famous bioluminescent creature. There are over 2000 species of firefly (which are also known as lightening bugs). For example, Photinus pyralis produces light via a chemical reaction between a pigment called luciferin and oxygen. Carbon dioxide is the most common chemical which is released by this reaction. Luciferin has a number of applications for people, including for use in blood banks to examine whether red blood cells are breaking down. Fireflies can regulate the amount of oxygen that enters their abdomen (where the chemical reaction takes place), which can create a flashing pattern. In case you were curious, fireflies hibernate during the winter in larvae stage. In Malaysia, fireflies have been known to flash in unison. While fireflies regulate their lights individually, they receive feedback from other light flashes around them. Even fireflies are susceptible to peer pressure. Source

It is not just fish and insects that glow, types of mushrooms called foxfire have the ability to produce light as well. The species Armillaria mellea is a variety of honey fungus that glows in the evening when it grows in rotting hardwood trees. This species causes root rot in a variety of plant species, so its glow is a part of the circle of life. Another type of fungi that emits light is found in Brazil. These mushrooms which are part of the genus Mycena provide a slight green glow at night. Of the 500 species of mushroom that are filed under Mycena, only 33 are known to be bioluminescent. Foxfires have had practical applications as people from various parts of the world have used the mushrooms as a natural lantern. Source

There are a number of animals that glow with a helping hand from scientists. Researchers have introduced substances such as green fluorescent protein to animals including rhesus monkeys and pigs to examine a wide variety of ailments. For example, in 2008 scientists infected unfertilized rhesus monkey eggs to study Huntington’s disease. The study examined the disease’s effect on monkey brains. Green fluorescent protein was introduced to pigs by researchers in Taiwan to study the development of adult stem cells. Fluorescent proteins have also been introduced to animals to study cloning. Red fluorescent protein was introduced to cloned cats in 2007 via DNA by scientists in South Korea. The function of mice brains have also been studied at Harvard by introducing cyan, red, and yellow fluorescent protein. Individual neurons were given different colors to study how neurons work together in a distributed fashion. Source