Glass frog transparency is a camouflage mechanism

Hyperaxion May 26, 2020

Research shows that this amphibian species predominantly has a colorless belly and legs to protect itself from predators.

After observing glass frogs, a species found in the Amazon rainforest and Central America, scientists from the University of Bristol, in the United Kingdom, from McMaster University, in Canada, and from the University of the Americas in Quito, Ecuador, found that the transparent skin of these amphibians works as a camouflage mechanism. The findings were published in an article in the scientific journal PNAS, this Tuesday (26).

Glass frog transparency is a camouflage mechanism

Using a combination of methods to analyze these animals – field studies, computational model, and computational detection experiments – the researchers realized that the colorless body helps these amphibians to get rid of predators. In this way, if they are close to darker vegetation, they will be darker. If they are placed on light-colored leaves, they acquire this color.

“We also found that the legs are more translucent than the body and so when the legs are held tucked to the frog’s sides at rest, this creates a diffuse gradient from leaf colour to frog colour rather than a more salient sharp edge. This suggests a novel form of camouflage: ‘edge diffusion’,” said the research’s lead author, James Barnett, in a note.

Barnett explains that transparency is relatively common in aquatic species, as the tissues of these animals have refractive indexes similar to the surrounding water – which is not the case with air. “So, transparency is predicted to be less effective in terrestrial species,” explains the researcher.

According to the expert, these frogs are not exactly transparent, but translucent. “Although glass frogs are one commonly cited example of terrestrial transparency, their sparse green pigmentation means they are better described as translucent,” he notes.

“We now have good evidence that the frogs’ glass-like appearance is, indeed, a form of camouflage,” said Professor Nick Scott-Samuel, a visual perception expert at the University of Bristol’s School of Psychological Sciences and research supervisor. Scientists point out that animal camouflage has been a teaching example of the power of Darwinian natural selection.

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