The Great Smoky Mountains' Incredible Firefly Light Show

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Today, the rare Smoky Mountain fireflies are a tourist attraction. Twenty years ago, science didn’t believe they existed.  

At exactly 9:27 P.M., when dusk slips into darkness in the Great Smoky Mountains National Park, the “light show” begins. It’s June, and for two weeks in Elkmont, Tennessee, the fireflies pool their efforts. Instead of scattershot blips of light in the summer sky, the fireflies—thousands of them—pulse this way for hours, together in eerie, quiet harmony. It’s as if the trees were strung up with Christmas lights: bright for three seconds, dark for six, and then bright again, over and over. It continues this way for hours.

As a child, Lynn Faust would huddle with her family on the cabin porch to watch the spectacle. They’d sit, mesmerized by the “drumbeat with no sound.” And though they’d appreciated the show for generations, Faust never thought the event was newsworthy. “I’d assumed there was only one kind of firefly and thought they did a nice show in the Smokies,” she says.

The natural world has long enchanted Faust. In college, she majored in forensic anthropology and minored in forestry. In her twenties, she circumnavigated the globe for three years, visiting islands you could only get to by boat, learning about cultures before they disappeared, pursuing underwater photography. Today, at 60, she’s a naturalist who writes scientific papers and field guides about fireflies. But she wasn’t always obsessed with the insect. In fact, her academic interest began only in the ’90s, when she read an article by Steven Strogatz, a Cornell mathematician, in which he marveled at a species of Southeast Asian firefly that synchronized its flashes. Highlighting how rare this phenomenon was, Strogatz noted that there were no synchronous fireflies in the Western Hemisphere.

This struck Faust as odd. It contradicted the light shows she had seen growing up. As she dug deeper, Faust found that while there had been more than 100 years of colloquial accounts of North American fireflies flashing in sync, scientists discounted those reports, attributing them to lore or optical illusion. Faust knew the truth: that her Tennessse fireflies were every bit as special as the species in Asia. But how could she prove it?

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Fireflies—or lightning bugs—may be the closest thing nature has to a magic trick: lighting the world from the inside out. Technically, they are bioluminescent beetles. Their glow comes from an internal chemical reaction that combines oxygen and calcium with a series of enzymes, including a key light-producing one called luciferin. The bugs flash for lots of reasons: to communicate, to attract mates, to scare off predators. But for creatures so striking, they’re also common. There are roughly 2,000 species worldwide and 125 or more in North America alone, where catching them is a childhood rite of passage.

More than 20 years ago, Faust wrote a letter to Strogatz after reading his article. He connected her with Jonathan Copeland, a biologist and professor at Georgia Southern University who was studying firefly behavior in Malaysia and Indonesia. Copeland was skeptical of Faust’s tale. Reports of synchrony had crossed his desk before but had never panned out. “The dogma said they do not synchronize in North America,” he says.

Still, he indulged Faust, asking her to describe what she’d witnessed by drawing a “musical score.” As a child, Copeland, a tuba player, dreamed of playing with the Boston Symphony. Ever since, music dominated his approach to the natural world. In grad school, he’d studied and documented the rhythmic lunge and strike patterns of praying mantises. He took a similar slant on firefly behavior and found that if people charted the synchronic rhythms they were witnessing, he could separate a bogus account from a real one. Putting pencil to paper, Faust was nervous. “To look at it scientifically is very different from sitting in your rocking chair with a blanket and enjoying it,” she says. “I didn’t want to sound like a complete idiot.”

When her note arrived, “it looked like synchrony on paper,” says Copeland. In June 1993, he was intrigued enough to make the eight-hour drive to Elkmont. He pulled into the cabin’s driveway as dusk fell, no trace of the insects to be seen, and promptly fell asleep—only to wake up to flashes of light all around him. “It was completely obvious—no doubt about it!” he remembers. He rushed to find a pay phone to call his colleague Andy Moiseff. “It must have been about midnight,” he says. “I said, ‘Andy, Andy, you’ve got to see this, they’re flashing synchronously!’ Andy laughed and said, ‘Prove it,’ like any good scientist.” The following summer, that’s exactly what Copeland, Faust, and Moiseff, a professor of physiology at the University of Connecticut, set out to do. It was an unlikely partnership, but the trio made a formidable team. Copeland is a neuroethologist—he studies the neural basis for animal behavior. Faust, an unflappable outdoorswoman and keen observer, knows the area and its wildlife like home. And Moiseff is a computer whiz, with a proclivity for dreaming up theories and building devices to test them.

The three hauled lab equipment, microscopes, video cameras, computers, and insect specimens to sites throughout the Smokies. They started in Elkmont but quickly branched out to determine how widespread the phenomenon was. They hauled bugs back to the lab to do frame-by-frame analyses of the flashes. In the wild, “they were obviously in sync,” Copeland says. But when they repeated the test with individual fireflies in one-gallon freezer bags, the behavior changed. If an insect couldn’t see another, they no longer flashed synchronously. By 1995, the team had the data they needed.

“This was red-hot news in the firefly community,” says Copeland. There are four synchronous species of firefly known in Asia, and they are smaller than the team’s species, Photinus carolinus. “Their flash is wimpy in intensity, but what they lack in flash intensity, they make up in numbers,” Copeland says. They usually remain stationary in trees along the river, unlike carolinus, which fly around in the woods. “Ours are more complicated,” says Faust.

Proving synchrony existed in fireflies in the Western Hemisphere was exciting, but it raised questions about why they flashed this way. And how was that different from what their cohorts did in Asia or, for that matter, from the way their asynchronous relatives behaved in North America and even elsewhere in the park? For the next two decades, Copeland and Moiseff would study the fireflies with Faust each summer, determined to understand these magical creatures. But just as they were getting close, everything in Elkmont changed.

In the beginning, the team had the woods to themselves. “In the old days, there would be the three of us and the odd stranger who was fishing,” says Moiseff. In fact, when Faust first informed park officials about the light show, they didn’t believe her. In 1992, her family had to give up its cabin when the government took control of the resort community’s leases. By then, Faust had noticed that the firefly behavior seemed to be localized: The light show didn’t appear to be taking place even half a mile away from this settled location. She hypothesized that the synchronous behavior could be linked to the unusual conditions near the homes. But when she pointed it out, parks officials assumed her claims were a trumped-up attempt to keep her cabin.

Finally, in 1996, park administrators sent a ranger to the researchers’ campsite to investigate. “It was a funny night,” Faust recalls. “We had this ancient computer set up on the porch and Christmas lights strung across the hill to see if we could control the rhythm of the firefly flashes with the lights going off and on. He was like, ‘Where are they?’ And suddenly, there they were. The guy goes, ‘Oh, my God.’ He said that about six times,” says Faust. The next night they had 20 rangers watching.

By the early 2000s, word had spread. According to one of the park’s supervisory rangers, Kent Cave, “There were fender benders, road rage, crowds of people.” The Smoky Mountain fireflies had become a bona fide tourist attraction. In 2006, the park instituted a trolley service from a parking lot to the viewing area for peak nights, closing access to individual cars. “People were driving up. They might have driven five hours from Alabama or down from Lexington and couldn’t get in,” says Cave.

Today, tourists reserve parking spots in advance online. After the year’s peak firefly emergence has been predicted, reservations for the June viewings go live in late April. The spaces go in minutes. The light show has become the biggest of the park’s special events, with as many as 12,000 attendees in recent years. But as Cave puts it, “Our biggest headache is predicting when these little buggers are gonna flash.” There’s a system for that too. “The pressure of me telling people when to come see the fireflies began 20 years ago,” Faust says. “Like anything in nature, it’s not entirely predictable, but I’ve developed a mathematical way of figuring it out.”

Today, park entomologist Becky Nichols relies on Faust’s degree-day model to determine when the fireflies will emerge. The equation is specific to Photinus carolinus and relies on temperature data Faust and Nichols begin collecting in early March. “You take the high and the low temperatures and plug them into a formula to figure out the larvae’s accumulation of growth,” explains Nichols. “The issue in the past was that we didn’t have good temperature data.” Tiny temperature loggers fixed to trees for air temperature and to the ground for soil temperature have remedied that problem. Faust has her own data logger down the road as well, and the two women compare results as the numbers climb, hoping to come up with the same prediction independently.

Though they’re gratified that the public appreciates the light show, its popularity is bittersweet. The event is too crowded for the scientists to continue studying at the site, so they’ve decamped to other areas in the Appalachian Mountains. As Copeland says ruefully, “We can’t work there anymore because it’s a tourist attraction, and we’re largely responsible for that.”

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So why do Photinus carolinus flash together? No one has quite figured it out, Faust says. But there are theories. In a 2010 paper published in Science, Moiseff and Copeland suggest that synchrony keeps the female firefly from getting confused when searching for a mate. In an experiment using an electronic simulator with light-emitting diodes, they found that uncoordinated stimuli—too many lights coming from too many places at different times—inhibited the female firefly’s response. When flashes were coordinated, the females could clearly send their messages back to the males. Faust agree that synchrony in carolinus is related to mating.

Moiseff, who’s most interested in the firefly’s brain and nerve cells, wonders what it is about the insect’s eyes that helps it process information. Some data has shown that under the right circumstances, a firefly can determine where a flash is coming from. What this could suggest, he says, is that the insect’s brain might break information into different pathways for processing—something that primates and people do, but we don’t think of bugs doing. It’s a problem he’s still studying: “How does a simple nervous system accommodate that? What’s the mechanism?”

Moiseff also points out that Photinus’s synchrony is important not because the phenomenon is so rare but because it changes our perspective on the many ways in which living things interact. With just one proven case in the U.S., the gates opened wide for discovering others. In 1998, Copeland and Moiseff showed that a species on the Georgia and South Carolina coast, Photuris frontalis, was also synchronous. Additionally, the species Photinus pyralis, Copeland says, is “weakly synchronic.” Once you find other species doing this, “all of a sudden they’re not a freak of nature. Instead, they have a solution to a specific environmental need,” says Moiseff.

The last few years, Moiseff and Copeland have kept their firefly studies closer to home. “For the first 10 years, my spouse was very supportive,” says Copeland of his work in Tennessee. “Then she started asking questions about the significance.” He retires from his position at Georgia Southern this year, and, joking aside, considers identifying Photinus’s synchrony to be one of the highlights of his life. “I grew up as a suburban kid afraid of the dark, and I found myself [alone] in the woods with fireflies,” he says. “Serendipity—and a mind set that gets you away from cable TV—plays a role in science.”

Faust, for her part, is still involved with fireflies. She’s working on a field guide that will include images from her collection of more than 60,000 photos. And her family cabin still stands proudly in the same spot where she first saw the light show. But it isn’t quite the same. The cabin now belongs to the park, and she and her family no longer curl up on that porch under thick blankets, waiting for the pulsing spectacle to begin. One thing hasn’t changed, though: No matter how many times Faust has seen the show, Photinus carolinus’s return each summer is still a thrill. “The biggest kick is trying to predict the first night,” she says. “To see that first one and think, ‘Wow, that happened again.’”

This story originally appeared in an issue of mental_floss magazine. Subscribe here.

15 Animal Names That Can Be Used As Verbs

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iStock.com/fotojagodka

People can go fishing, rabbit on incessantly, dog one another, and horse around. But because of their usefulness in completing burdensome work, horse has also been used in (originally naval) slang since the mid-19th century to mean “to work to the point of exhaustion”—or, in the words of the Oxford English Dictionary, “to drive or urge at work unfairly or tyrannically.” But horses aren’t the only animals whose names can be “verbed.” From turtles to tigers, you can drop any one of these 15 creatures into your everyday conversation.

1. Bulldog

No one is entirely sure why bulldogs are called bulldogs, with different theories pointing to everything from their bull-like stature to their bullish faces to the fact that they might once have been bred to bait bulls. Whatever the origin, the bulldog’s strength and its robust, resilient behavior means that you can use its name as a verb meaning “to attack roughly,” or “to wrestle to the ground.”

2. Tiger

A tiger
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If you tiger, then you walk to and fro, like a tiger pacing in a cage. If you tiger something, then you paint or mark it with contrasting stripes.

3. Spider

Jumping spider
iStock.com/elthar2007

As well as being used simply to mean “to creep” or “to move like a spider,” if you ensnare or entrap something, or else cover it in a cobweb-like pattern, then you spider it.

4. Cat

British shorthair cat with expressive orange eyes
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Because the cathead is the horizontal beam at the bow of a ship that’s used to raise an anchor, the word cat has a number of nautical uses as a verb, including “to lift an anchor from the water,” “to secure an anchor,” and “to draw an anchor through the water.” But because shooting the cat was 19th century slang for being sick from drinking too much, you can also use cat to mean “to vomit.”

5. Vulture

White-backed vulture
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Vultures’ grim feeding habits and their remarkable flying ability have given the word two meanings as a verb in English. Feel free to use it to mean “to eat voraciously” or “to tear at your food,” or else “to descend steadily through the air.”

6. Owl

Owl in flight
iStock.com/WhitcombeRD

Owling (as well as being a short-lived social media craze) was once the name given to the crime of smuggling sheep and wool from England to the continent—a crime so-called because the nefarious “owlers” carried out their crimes at night. That might not be the most useful of words these days of course, so feel free to also use owl to mean “to act wisely, despite not knowing anything.”

7. Shark

It’s easy to presume that the use of shark as a verb to mean “to act like a predator” (which is the same shark as in loanshark, incidentally) derives from the deadly sea creatures. In fact, it might be the opposite: Both meanings of the word shark date back to the late 16th century, but it’s possible that the verb shark is the older of the two. If so, it’s possible that it comes from the earlier word shirk (in the sense of using deceit or trickery to avoid work) or else a northeastern French word, cherquier, which was often used in a phrase that essentially meant “to sponge of others” or “to act as a parasite.” So how did sea-dwelling sharks come to be called sharks? It’s possible the deceitful sharks gave their name to the menacing creatures, or else the two could be completely unrelated—and, thanks to a sea battle off the Yucatan peninsula in 1569, shark could in fact be a Mayan word.

8. Monkey

Chimpanzee looking surprised
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As well as meaning “to play the fool” or “to behave playfully”—as in “monkeying around”—monkey, like ape, can also be used to mean “to mimic” or “to copy someone’s movements or actions.”

9. Turtle

If a boat “turns turtle,” then it capsizes and flips over, so that it looks like a turtle’s domed shell floating atop the water. Because of that, to turtle something is to turn it upside down.

10. Snail

Burgundy snail
iStock.com/AlexRaths

For obvious reasons, snail has been used to mean “to move slowly” since the late 16th century, but because of the snail’s coiled shell, you can also use snail to mean “to draw or carve a spiral,” or “to roll into a spiral shape.”

11. Porcupine

Porcupine walking
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When your hair stands on end, feel free to say that it porcupined.

12. Canary

Canary birds take their name from the Canary Islands, which, somewhat confusingly, take their name from canis, the Latin word for “dog.” But in the 16th and 17th centuries, the canary was also the name of an energetic dance inspired by a traditional dance performed by the natives of the Canary Islands. And because of that, you can also use the word canary as a verb meaning “to dance in a lively fashion.”

13. Earwig

Earwig
iStock.com/Mr_Fu

Earwigs are so-called because they were once (thankfully erroneously) thought to crawl inside people’s ears as they slept. Through association with someone whispering clandestinely into someone’s ear, in the late 18th century eavesdroppers and people who seeked to secretly influence others became known as earwiggers—and so to earwig is to do precisely that.

14. Pig

Cute pig leaning on railing of his cot
iStock.com/Fotosmurf03

Pig has been used to mean “to give birth” since as far back as the 15th century in English (a fairly uncomplimentary allusion to a pregnant sow delivering a litter of piglets). But slightly less depreciatively, the living habits of pigs mean that it can also be used to mean “to huddle together,” or else “to live or sleep in crowded or dirty conditions.”

15. Dingo

A dingo
iStock.com/JohnCarnemolla

Because of their stereotypically sneaky behavior, to dingo on someone meant “to let down” or “to betray” them in 1930s Australian slang, while to dingo meant simply “to shirk” or “to back out of something at the last minute.”

This list first ran in 2016.

Photographer's Up-Close Images of Animal Eyes Will Have You Seeing Wildlife in a Whole New Way

A parrot eye
A parrot eye
Suren Manvelyan

Few people ever get close enough to a hippo, hyena, or crocodile to snap a photo of one, let alone get a detailed shot of their eyes. Yet that is exactly what theoretical physicist-turned-photographer Suren Manvelyan, of Armenia, has done. His macro photography series of animal eyes, spotted by My Modern Met, offers a rare look at the animal world, amplified.

Some of Manvelyan's eye photos—like that of the camel, which has three eyelids—look like strange landscapes on some distant, alien planet. The smallest details have been captured in his photos, from the kaleidoscopic irises of the chinchilla and chimpanzee to the shimmery edges of a raven's eye. If the photos weren't labeled, it might be difficult to tell what you were looking at.

"It is very beautiful and astounding," Manvelyan told Radio Free Europe/Radio Liberty. "The surface resembles the surface of other planets, with craters, rivers, and valleys. It looks like something from another world. Every time I photograph the eye, I feel myself traveling through the cosmos."

Manvelyan keeps his photography techniques secret, but he says he sometimes spends an hour with an animal just waiting to capture the right moment. To date, he has photographed both domestic animals (like a husky dog and Siamese cat) as well as exotic ones (including a variety of tropical birds and lizards). Check out some of his shots below, and visit his website to see more photos from this series.

Eye of a caiman lizard
A caiman lizard's eye
Suren Manvelyan

A camel's eye
A camel's eye
Suren Manvelyan

A chinchilla eye
A chinchilla's eye
Suren Manvelyan

A raven's eye
A raven's eye
Suren Manvelyan

A husky dog's eye
A husky dog's eye
Suren Manvelyan

A horse eye
A horse eye
Suren Manvelyan

A chimpanzee eye
Eye of a chimpanzee
Suren Manvelyan

A tokay gecko's eye
A tokay gecko's eye
Suren Manvelyan

[h/t My Modern Met]

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