(ORDO NEWS) — Biologists have found that thanks to the unique color glass frogs have become the owner of a special kind of natural disguise.
Glass frogs are known for their clear skin, but so far the reason for this curious feature has eluded the attention of biologists. A team of scientists from the University of Bristol, McMaster University and the University of Las Americas Quito attempted to establish the environmental importance of the transparency of a glass frog and thereby opened up a new form of natural camouflage.
Using a combination of field-based behavioral tests and computer visual modeling, the researchers identified one interesting feature. According to their article published in PNAS, although the transparency of a glass frog acts like camouflage, its mechanism is different from the mechanism of “real” transparency of objects.
Lead author of the work, Dr. James Barnett, explained: “Frogs are always green, but appear lighter and darker depending on the background. Such a change in brightness makes frogs less noticeable against the background of their immediate environment, mainly consisting of green leaves. We also found that the legs are more transparent than the body, so when they are pressed to the side of the frog at rest, a diffuse gradient appears from the color of the leaf to the color of the frog, without pronounced sharp edges. This circumstance suggests a new form of camouflage: “diffusion along the edges.”
Dr. Barnett remarked that scientists are often skeptical during scientific debates about how “transparent” glass frogs can actually be called.
“Transparency is essentially the perfect camouflage. It is relatively rare in aquatic species, and occurs when animal tissues have the same refractive index as the surrounding water. However, the refractive indices of air and tissues are quite different, so the transparency of terrestrial species with transparency should be worse. Indeed, transparent earthly creatures are extremely rare. Although glass frogs are one of the most commonly cited examples of “ground” transparency, their rare green pigmentation means it is better to describe these animals as translucent,” he concluded.
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