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Frog Finder

Ecologist Courtney Whitcher explores rainforests to study glowing frogs

May/June 2024

By Jennifer Hackett

Hidden in the darkness of tropical rainforests is a secret world. Those with sharp eyes might spot strange creatures in trees or by ponds, glowing orange or blue. By day, they’re ordinary-looking frogs, but they become something magical in the dim light of twilight!

Researchers recently found that many frogs biofluoresce, or glow. Biofluorescence is when animals or plants absorb high-energy light, like ultraviolet light, and reemit it as lower-energy light, like orange or green. This is different from animals that produce their own light, like fireflies. (That’s called bioluminescence.)

There’s a secret world in the tropical rainforest. You can only see it when darkness falls. Strange creatures in trees or near ponds glow orange or blue. By day, they’re ordinary-looking frogs. But they become magical after sunset!

Scientists recently discovered that many frogs have this glow. It’s called biofluorescence (bie-oh-floh-RES-uhns). It happens when animals or plants absorb high-energy light from the sun. They give it back off as visible light in colors like orange or green. (This is different from animals like fireflies. They produce their own light.)

Courtesy of Courtney Whitcher

The green glow on this frog’s chest and legs is a common type of biofluoresence.

Courtney Whitcher is an ecologist and evolutionary biologist studying biofluorescent frogs. She thinks glowing might be a “secret communication channel” that lets frogs talk to one another without predators seeing. Frogs have unique eyes that let them see the color of the emitted light. They glow the most at twilight, which is when the amphibians are most active and already talking with one another.

Whitcher first visited the rainforest on a high school trip to Costa Rica. “I experienced a night hike in the rainforest and fell in love with the environment,” she says. That led her to pursue a career in ecology. Today Whitcher is a graduate student at Florida State University, and she gets to do field research in the rainforest every year!

“Each day of research starts with going out at night to look for frogs,” she says. Whitcher scans ponds and tree branches, hoping to spot a frog to catch and bring back to her camp. Once she has a specimen, she holds the critter under a special lamp called an excitation light. She then peers at the frog through filtering goggles. The goggles allow her to see only the light from the frog’s biofluoresence. She can then record the color and brightness of the frog’s glow. Since 2017, Whitcher and other researchers have recorded biofluorescence in more than 150 frog species in South America.

Whitcher loves sharing her fascination with biofluorescence. Seeing the world in a new way is her favorite part of her research. “We are living in, and surrounded by, a glowing fluorescent world just waiting to be discovered,” she says.

Whitcher first visited the rainforest on a trip to Costa Rica in high school. “I fell in love with the environment,” she says. She decided to pursue a career in ecology. Today she’s a graduate student at Florida State University. She gets to do research in the rainforest every year!

Whitcher goes out to look for frogs every night of a research trip. She scans ponds and tree branches, hoping to spot one. When she does, she catches it and brings it back to her camp. Then she holds it under a special lamp that gives off high-energy light. She looks at the frog through filtering goggles. They allow her to focus on the frog’s glow. She records its color and brightness. Since 2017, she and other scientists have found that more than 150 frog species in South America glow.

Whitcher loves sharing her interest in biofluorescence. Her favorite part is seeing the world in a new way. “We are living in a glowing world just waiting to be discovered,” she says.

USING METRIC PREFIXES

The U.S. uses the customary system to measure length, mass, volume, and temperature. But most countries—and scientists like Whitcher—use the metric system. When you’re working within the metric system, you can use prefixes to determine how much greater one unit is than another.

EXAMPLE

A frog in the Amazon Rainforest reemits red light that has a wavelength of 690 nanometers. What’s that in centimeters?

STEP 1

Find the conversion rate between the original unit of measure and the base unit of measure (the unit with no prefix).

STEP 2

Convert the original quantity into the base unit of measure.

STEP 3

Convert the base unit of measure to the desired metric unit.

STEP 4

Check the reasonableness of your answer. Centimeters are larger than nanometers, so there should be fewer centimeters than nanometers. This answer makes sense.

So 690 nanometers is equal to 0.000069 centimeters.