Many frogs are capable of emitting a slight green or yellow glow during the dim hours.
In South America, a survey of hundreds frogs shows that Biofluorescent frogs are more common than everResearchers report that the frogs’ ghostly colors may be more common than previously believed in a preprint published on July 28 by bioRxiv.org. The ghostly colors may have a role in the frogs’ communication with members of the same species, the scientists say.
The findings “are a reminder to check our own perception as humans,” says Jennifer Lamb, a herpetologist at St. Cloud State University of Minnesota, who was not part of the research. “We are very visually dominant in terms of our senses. And other animals are too, but they might be experiencing that visual world differently than we are.”
It is found in a wide variety of creatures. When an organism absorbs a wavelength or color and then reemits that light with a lower energy, it is called biofluorescence. Researchers have observed this trait in an increasing number of species over the last few years. Flying squirrelsThe following are some examples of how to get started: The platypus is a species of animal that lives in the southeastern United States.The following are some of the ways to get in touch with us: Nests of certain wasps (SN: 11/6/20, SN: 9/2/21).
Fluorescence The first time this was discovered in frogsSince 2017, researchers have tested more amphibians for fluorescence, says Courtney Whitcher, an evolutionary biologist at Florida State University in Tallahassee. Courtney Whitcher, evolutionary biologist and Florida State University Tallahassee, said that researchers have since tested more amphibians to see if they fluoresce. She says that the biofluorescence of frogs has been studied using only one or two light sources, typically violet or ultraviolet.
Whitcher, along with her colleagues, tested frogs under five different wavelengths of light ranging from UV to green. From March 2022 to May 2022 the team captured 528 individual frogs and shined lights on them in Brazil, Colombia and Ecuador, and measured any re-emitted light.
The 151 species of frogs they tested all had some level of fluorescence. This ranged from 2 percent to over 90% of the original intensity of light. Prior to the study, fewer than 12 of 42 frogs species had been tested and were fluorescent.
The frogs’ green and orange fluorescence was most intense under blue light that dominates at twilight. It is similar to the way Many salamander species are fluorescent. under blue light, Lamb says (SN: 2/27/20).
Fluorescence in land living animals “was recently thought to be rare, and when people go out looking for it, surveying across multiple species, it turns out it’s everywhere,” says zoologist Linda Reinhold, recently a graduate student at James Cook University in Queensland, Australia. “It was only because no one had looked before.”
Many of the frogs’ body parts that strongly fluoresced are also involved in signaling to other frogs. The fluorescence was mainly concentrated on the throats and undersides of the frogs. These are used for courtship rituals. “While they’re calling, that vocal sac region is expanding and contracting,” Whitcher says. Fluorescence can make the display more visible.
Researchers say that other frogs are likely to be able to see the green glow. The team found that in the twilight hours — a time when frogs tend to court and mate — frog eyes are quite sensitive to the particular green light that’s emitted from the frogs’ skin. The orange fluorescence on the other hand may be intended to a different recipient, such as predators. Whitcher explains that it could be used as a camouflage, or warning signal.
It’s “astonishing” how widespread fluorescence is among these frogs, says evolutionary biologist Mark Scherz, of the Natural History of Denmark in Copenhagen. “Not a single one of the species they tested failed to fluoresce,” he says, adding that testing the frogs against a variety of light wavelengths might help explain the fluorescence rate.
He doubts that the fluorescence is strong enough to be used for communication. According to him, the sunlight is brighter in daylight than at sunset, so it may be difficult to convert that light into a green glow.
Whitcher is now investigating whether fluorescence in male frogs influences female frogs’ mating choices. “Maybe there’s a threshold of fluorescence intensity that is needed in order to elicit some kind of behavioral response,” she says.
