First-Ever Fluorescent Frog Found In Argentina, But Why Does It Glow?

Scientists believe they may have discovered a first in the animal kingdom – a fluorescent frog that emits a bright, colorful glow once exposed to ultraviolet light.

According to an NPR report, the South American polka dot tree frog doesn’t look outwardly peculiar upon first glance. But when the frog was analyzed by researchers, they discovered that it glows bright blue-green if placed under an ultraviolet light. This marks a trait that had, until the recent discovery, not been found in amphibians, though fluorescent animals aren’t exactly unique or too unusual in the broader animal kingdom.

Prior to the discovery of the fluorescent frog, researchers had previously found that some species of fish and sea turtles can emit similar glows, with parrots standing out among land animals as having this capability. But study co-author Norberto Peporine Lopes of the University of Sao Paulo noted that there was another “surprise” discovery to be had – the interactions between the chemical agents that cause the frog to emit its distinctive glow.

“Three molecules — hyloin-L1, hyloin-L2 and hyloin-G1 — in the animals’ lymph tissue, skin and glandular secretions were responsible for the green fluorescence. The molecules contain a ring structure and a chain of hydrocarbons, and are unique among known fluorescent molecules in animals.”

It may be easy to conclude that the fluorescent frog is actually a bioluminescent one, but as Quartz explained, the two terms are ultimately different despite their similarities. Bioluminescent creatures, such as fireflies, use chemical agents to generate their own light. Fluorescent creatures, on the other hand, absorb light in short wavelengths and re-emit that light in longer ones. The South American polka dot tree frog is unquestionably a fluorescent creature, but Quartz stated that it differs from other animals of this kind in a way that scientists haven’t been quite able to fully nail down. Still, the researchers offered some theories that may point to the possible purpose of this fluorescence.

The South American polka dot tree frog, which is known by the scientific name Hypsiboas punctatus, also happens to be an extremely fluorescent one, emitting about 18 percent of a full moon’s capability to emit visible light. According to Nature, that’s just the right amount of light that would allow related frog species to see. As the intricacies of the fluorescent frog’s visual system remain unknown, the researchers hope to study the animals further to see if their fluorescence is visible to their own eyes.

As for the primary purpose of the fluorescence, the frogs may use it as a tool for communication, more specifically as a way for males to attract females. As a mating device, the fluorescence could help send sound and smell cues, and also help males of the species let females know where they are located. In other words, Lopes believes that this is their way to “coordinate the attraction.”

City University of New York marine biologist David Gruber, who was not involved in the study, first found fluorescence in hawksbill sea turtles in 2015, and he believes that the new study is an “exciting” one that may nonetheless spur more research projects to determine the exact purpose of fluorescence in animals.

“‘It opens up many more questions than are answered,’ he says — including the ecological and behavioral function of fluorescence.”

But is the polka dot tree frog the only fluorescent frog species out there? University of Buenos Aires herpetologist Julian Faivovich told Nature that he’s planning to study the other 250 tree frog species with translucent skin to see if there are others that carry the same fluorescent traits.

“I’m really hoping that other colleagues will be very interested in this phenomenon, and they will start carrying a UV flashlight to the field,” said Faivovich.

[Featured Image by Elena11/Shutterstock]

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