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Learning from the Firefly and Its Language of Light

Kathrin Stanger-Hall smiling in front of greenery.
Kathrin Stanger-Hall. Credit: Yelena Pacheco.

AAAS Member Kathrin Stanger-Hall was in North Carolina collecting data for her doctorate when she saw her first firefly. It was a bit like Christmas, she says, with all the flickering lights. The hidden meaning behind the beetles’ flashing lights became the focus of her career. “Once I discovered fireflies and their flash signals…I was totally hooked!” she recalls.

For centuries, the chemical flashes from these intriguing insects – also known as lightning bugs – have inspired people of all ages with a love and fascination of nature.

But how does the magic work? There is a light organ on the small beetle’s belly. Light is produced when oxygen combines with magnesium, adenosine triphosphate (ATP) and the chemical luciferin in the presence of luciferase, a bioluminescent enzyme.

There are about 150 species of fireflies in North America, and more than half seek out mates using light signals. Those that don’t produce light use chemical signals like pheromones to attract mates instead.  

At the University of Georgia, Stanger-Hall’s lab studies firefly communication by focusing on light signal evolution, including how an organism makes a signal, what the signal looks like and what role the receiver plays.

With fireflies, her team is especially interested in the evolution of the color of their light, which ranges from green to orange. Different colored flashes stand out more with different backgrounds. For example, a yellow flash can be detected much easier in a green environment than a green flash would, and a green flash can best be viewed when it is completely dark.

“Of the 80 to 100 fireflies that produce light, all have their own specific way they flash,” says Stanger-Hall. “So basically, their flash patterns are a type of visual Morse code. That is how they can recognize their mate. There are more than 80 different languages out there,” she says.

With the common Big Dipper firefly, (Photinus pyralis), for example, the male emits a long flash and immediately goes to a higher position, looking like a J, or the Big Dipper. He hovers and looks for a female response. If there’s a female of the same species watching, she turns her backside out and flashes back. If the male recognizes it, he eventually lands nearby. They use their antennae to sample each other’s body chemistry and then usually they mate.

Back in the lab with specimens, the research team uses more than 500 genes to study how fireflies are related to each other. They also utilize these phylogenies to test evolutionary hypotheses of light color evolution.

Stanger-Hall’s communication research extends to humans as well. Her 2018 selection as a AAAS Fellow comes in part for her efforts to help improve the way students learn, especially in boosting critical thinking skills that are vital to becoming a scientist.

“I basically look at any communication as sender, information exchange and receiver. That’s what I study with wildlife, but also in the classroom as a teacher,” she explains. “In no way is communication one-way. Similar to how fireflies send signals back and forth, students must answer questions and challenge the knowledge they receive to understand it more fully.” Stanger-Hall is always developing new ways of helping her students learn because she is aware of the diverse ways to communicate.

She says students often come back to her and tell her they still use the study skills they learned in her Intro Biology class.

Those critical thinking skills are also important for a new generation communicating science to the public. Stanger-Hall has developed a Communicating Science Lab for graduate students at the University of Georgia.

“I think we need to train our graduate students to be able to communicate to the general public, to the taxpayers who pay for their research, to know what they are actually doing, to connect, to outreach,” she says.

Stanger-Hall’s lab has many undergraduate and even high school students. She and her team do a great deal of outreach to younger students to let the firefly’s “language of light” lure them into a love of science.

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Marsha Walton

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