Things that naturally glow in the dark can capture the imagination of people of all ages. Bioluminescence is a chemical reaction inside living things that produces light. Two key elements must be present for bioluminescence to occur. When luciferase and luciferin combine under the right conditions, they generate light. Many different species have evolved to radiate light throughout history. It can occur in bacteria, birds, fungi, insects, and even marine life. The Southern US is home to many of nature’s night lights. We’ll tell you when and where you can find things that naturally glow in the dark. Nighttime is the right time to discover bioluminescence in your backyard.
This is Part Two of our bioluminescence series. We’ll explore bioluminescent mushrooms and marine life. Check out Part One if you missed it.
Bioluminescent mushrooms aka foxfire
Aristotle was the first known person to coin the term foxfire in 382 BC. He documented a mysterious light, distinct from fire, emanating from decaying wood. He noted that it was cold to the touch. The philosopher and scientist was describing bioluminescent fungi. There are 71 verified species of light-emitting fungi in the world. All of them emit light 24 hours per day. Scientists are still unclear why they do so. Some believe it’s to attract insects that can help spread the mushroom’s spores.
In the Southern US, we have a few species of mushrooms where the fruiting body lights up the night. In many cases, though, it’s the underground mycelia that glows. Mycelia is kind of like the roots of a fungus. You can’t observe that part of the mushroom in nature unfortunately.
Finding bioluminescent mushrooms in the wild is not easy, but it can be done. Be cautious because some mushrooms are poisonous if consumed. Your best chance to find bioluminescent mushrooms is during the day. Collect a small specimen in a wooden or natural basket so that the spores get released back to the forest floor. Once you’re back home, go to a dark room and wait for your eyes to adjust. After they do, you should see the mushroom gills glow.
Otherwise, try damp or rainy nights since moisture is believed to play a role. Search for them on nights with a new moon. Allow your eyes to fully adjust to the darkness. Look high and low. Then follow the green glowing light.
Eastern jack-o’-lantern mushroom (Omphalotus illudens)
Eastern jack-o’-lantern mushrooms are orange and glow, just like their namesake. You can also call them “jacks” for short. The mushroom caps and stems can grow as large as 6 inches wide and 6 inches tall. Their caps start off rounded with a central bump. But they become flat and then cup-shaped as they mature. They have true gills that run downwards towards the stem. They grow in large clusters.
Their thick, bright orange flesh makes them easy to confuse with chanterelle mushrooms. But be careful. Eastern jack-o’-lanterns are poisonous if consumed. Touching them is ok, but don’t attempt to eat them. They will cause major gastrointestinal distress. Learn how to tell them apart.
When and where to find eastern jack-o’lantern mushrooms
In the Southeastern US, jacks grow in hardwood forests from summer to fall. You’ll find them in large clusters of up to 15-20 mushrooms between June and November. Look for them at the base of trees and decaying stumps, especially oaks. They also grow over roots on the forest floor. They’re saprophytic fungi. That means their job is to break down dead matter. They help to decompose fallen logs and branches, returning nutrients to the soil. In complete darkness, you can see eastern jack-o’-lanterns’ gills glow green. They’re known to continue emitting light for as much as 50 hours after being picked.
Southern jack-o’-lantern mushrooms (Omphalotus subilludens) are a similar species. They grow in the Gulf Coast of Florida and Texas. You can also find them from late summer to fall in similar habitats.
Bitter oyster mushroom (Panellus stipticus)
Bitter oyster mushrooms are one of the brightest-glowing mushrooms on Earth. This mushroom is common and widely distributed around the world. But only strains from Eastern North America are regularly bioluminescent. Bitter oysters grow in overlapping clusters. They first appear as small, white knobs. Then they slowly develop curved, flat overlaying caps that grow to be about 1.5 inches wide. The stems are less than an inch high. Their color can vary from dingy white to pale yellow to orangish brown. You’ll find their forked gills on the underside of the cap close together. The fruiting bodies can last for months.
Bitter oysters are much smaller than the similarly named oyster mushrooms. But bitter oyster mushrooms are inedible. They’re not poisonous, but they don’t taste good. In traditional medicine, this mushroom has been used to stop bleeding. They’re also being studied for their ability to break down environmental pollutants.
When and where to find bitter oyster mushrooms
You’ll find bitter oysters in the slow-growing hardwood forests of the US South. Especially in the Appalachian Mountains. This fungus likes to grow on birch, blue-beech, hickory, maple, oak, and pecan trees. They’re also reported to grow on loblolly and eastern white pine trees. You’ll find bitter oysters year-round, but they’re most common from late summer to early winter. They’re also saprophytic and break down decaying matter. Look for them on branches, logs, and stumps. The gills and mycelia of the bitter oyster will glow green in complete darkness.
Honorable mention mushrooms
There are a couple of other noteworthy bioluminescent mushrooms. But their light is not easily visible to the naked eye. In some cases, the fruiting body glows so faintly that it’s only observed using cameras or x-rays. Or just the underground mycelium glows brightly.
Bleeding fairy helmet mushrooms (Mycena haematopus) faintly glow and have glowing mycelia. They grow in groups joined at the base on old tree stumps and decaying logs. Even if you can’t observe the glowing parts, it’s exciting to know these bioluminescent fungi are out there. You can find them across most of North America.
There are two species of honey mushrooms known to be bioluminescent. Armillaria mellea and bulbous honey fungus (Armillaria gallica). The gills of the honey mushroom occasionally glow green but very faintly. Honey mushroom mycelium glows more brightly than their gills. They’re symbiotic with conifers and hardwoods. You can find honey mushrooms throughout North America growing in clusters at the base of these trees.
Bioluminescent marine life
Many sea creatures have evolved to create their own light. Especially at the lowest depths of the ocean where sunlight cannot penetrate. In the South, we’re lucky to have glow in the dark marine life at the surface of the ocean, too.
Dinoflagellates
Dinoflagellates are single-celled microscopic algae. They’re plankton that float on or near the ocean surface. But they’re also found in some freshwater habitats. Some genus of the species are bioluminescent. They emit short flashes of blue-green light when disturbed. It can look like a shimmering glitter bomb in the water. Their sparkling serves as defense and offense against predators. They can startle predators when they flash, disrupting their feeding pattern. The light they emit can also attract larger predators that may feed on what’s trying to eat them. It doesn’t take much to trigger this oceanic light show. Any motion in the water can activate a shimmer that you can see along the surface. Splashing waves, swimming, or even a passing watercraft. But it only occurs at night thanks to their circadian clock.
When and where to find dinoflagellates
Would you like to experience the wonder of a blue glowing sea? One of the best-known places to see bioluminescent dinoflagellates is along the Space Coast of Florida. Cocoa Beach and the Indian River Lagoon are plentiful with them in the summertime. But if you’re lucky, you can spot them on many Southern US coastal beaches. They’ve been reported all along the Atlantic and Gulf coasts. It’s a special experience you won’t ever forget.
Comb Jellies
Comb jellies are zooplankton, tiny animals found at the sea surface. These predators use hair-like features to propel themselves through the water. They’re flanked by rows of bioluminescent “combs” called cilia. Though they’re similar in name to jelly fish, they don’t sting. They’re completely clear except for the cilia that will glow blue-green light. Some emit an iridescent or rainbow-colored light, too. Similar to dinoflagellates, comb jellies will light up when triggered by movement. Scientists aren’t sure why comb jellies do this.
When and where to find comb jellies
You can find comb jellies anywhere from shallow coastal waters to the deep sea. There are two common comb jellies you can find along the Southern Atlantic coast. Sea walnuts (Mnemiopsis leidyi) and pink comb jelly (Beroe ovata). In Florida, you can find large blooms from October through May. But they’re around all year long. In North Carolina, they congregate in large numbers in spring and summer. Though they can also be found year-round. Have you ever experienced these glowing orbs of the sea?
Want to learn more about bioluminescence in the South?
Experiences that inspire wonder can help improve your mental health. Southern forests and wetlands are filled with awe-inspiring phenomena. That’s one of many reasons we must do everything we can to protect them. Appreciating the beauty around you can help you find your own glow within. There are few things as marvelous as those that light up the night. I hope this inspires you to explore the many living things that glow in the dark. Be amazed by the bioluminescence you can find in your backyard.
If you enjoyed this, check out Part One in our bioluminescence series: Things that Glow in the Dark: Fireflies, Lightning Bugs, and More
The best way to protect bioluminescent species is to protect the places they rely on to survive.
Act now to protect the forests and wetlands wildlife depend on.