The first time I experienced bioluminescence in nature was when I was a child living in Houston, Texas. I remember running around barefoot in the grass on a summer evening, trying to catch fairy-like “lightning bugs” in a jar. Now, as an adult and a conservationist, knowing fireflies are gravely threatened due to habitat loss and pollution from artificial lights, I shudder to think I ever tried to capture them.
The next time I experienced bioluminescence was when I was a teenager and my family took a scuba diving trip to the Cayman Islands. Grand Cayman is just a two-hour flight from Houston, so it was one of my dad’s favorite getaways. An avid diver, he has a family rule that he’ll get any child or grandchild scuba certified if they’re interested. So, my brothers and I learned to dive as teenagers.
On one trip, we did a night dive and that’s when I first saw bioluminescent plankton in the ocean. There was a magic to it that captivated me. I wanted everyone in the world to see what I saw: an awe inspiring natural beauty encapsulated in tiny radiant shimmers bobbing in the waves.
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Bioluminescence is a naturally occurring phenomenon that can be found in organisms in the ocean’s depths as well as on land. However, 80 percent of the living organisms that display it are found in the ocean.
According to the American Museum of Natural History, the glow from bioluminescence occurs when a substance called luciferin reacts with oxygen. The subsequent release of energy, which is facilitated by an enzyme called luciferase, emits the light. To glow on a regular basis, organisms must continually absorb fresh luciferin either through their diet or by producing it on their own.
The reasons that plants, insects, and animals evolved to glow are varied. However, the reasons are most likely similar to why you or I would choose specific items of clothing to wear. One outfit might be to look attractive to potential mates, another might be to let fellow members of our “tribe” identify us, and still another may be to ward off unwanted attention.
Adult male fireflies use specific flashing patterns to attract females for mating, which is why light pollution from human beings has disrupted firefly breeding. Glow worms, on the other hand, emit light to attract prey.
Over 75 species of fungi are known to be bioluminescent, though there is some disagreement among mycologists as to why. Some believe the glow is to attract animals who will graze on it, and therefore spread it, while others say it’s to deter grazing.
Bioluminescence also appears in ocean creatures for varied reasons. According to NOAA, most marine life, including single-cell organisms, shrimp, squid, octopuses, fish, and sharks, possess some level of bioluminescence. The glow can be used to ward off predators, to lure prey, or to communicate with fellow members of the same species.
While the world’s organisms may have practical reasons for glowing, I for one think that making the world more beautiful is as compelling a reason as any.
As mentioned above, fireflies are among the few land organisms that emit bioluminescence.
This video from National Geographic explains the phenomenon:
The first time I ever saw bioluminescence in mushrooms was in the work of nature photographer Petar Belobrajdic. These glowing ghost mushrooms were photographed on the east coast of Australia during “fungal season,” which is autumn in the Southern Hemisphere.
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Another bioluminescent fungi, bitter oyster mushrooms can be found in Asia, Australia, Europe, and North America. They grow in clusters on tree trunks – notably deciduous trees, such as beech, oak, and birch – and they can also be found on downed logs and stumps.
When it’s light, oyster mushrooms look like ordinary mushrooms. But when it’s pitch black, you can see their magic mushroom glow.
Glow worms are beetles in their larval stage, and there are four families of them that are bioluminescent. While males may have bioluminescence, those with the most glow are the females.
While beauty is in the eye of the beholder, I would argue that the most lovely bioluminescent organisms are jellyfish. Invertebrates floating in the sea, they are in the ideal setting to show off their hypnotic glow.
Because sunlight doesn’t penetrate beyond 200 feet, or 60 meters, emitting a glowing light can come in hand in the ocean’s depths.
This video from Dylan Brennan shows some rather stunning bioluminescent jellyfish:
While it’s up for debate why the firefly squid glows, what is known is that these cephalopods (a class of marine animals that includes squids, octopuses, and nautiluses) are avid hunters. They feast on small crustaceans, fish, and even other squids and generally live at depths of 650 – 1,300 feet (200 – 400 meters).
Some species of sea slugs, including Costasiella kuroshima, affectionately known as leaf sheep, also display bioluminescence. In the case of leaf sheep sea slugs, the animals can perform photosynthesis. Like plants, they can utilize sunlight to create energy from carbon dioxide and water. This, coupled with the algae that makes up their diet, causes them to look like they’re glowing green.
In this video, photographer and marine biologist David Gruber shares his footage of bioluminescence appearing in other marine creatures, including sharks, sea turtles, seahorses, and others.
You don’t have to hire a submersible or even go scuba diving to see bioluminescence in the ocean. Glowing phosphorescent marine algae, or plankton, can be found on the ocean’s surface all over the world.
In Mosquito Bay in Vieques, Puerto Rico, there is one bay in particular that is so full of phosphorescent plankton that it’s nicknamed “Bioluminescent Bay.” Simply disturbing the water stimulates a reaction in the plankton, which causes the glow.
In this video, Mike Cory, creator of the travel vlog Fearless and Far, takes a kayaking tour in Mosquito Bay:
In this video, Brendon Hayward captures surfers riding glowing waves off the coast of Los Angeles:
Apparently humans aren’t the only ones who enjoy riding glowing waves.
In this video from ABC 10 News, dolphins are filmed frolicking in the glow:
Isn’t the Earth a wonderful place?
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