Biologists have found that thanks to the unique coloration of glass frogs have become the owner of a special variety of natural camouflage.
Glass frogs are known for their transparent skin, but until now 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, tried to establish the ecological importance of glass frog transparency and thus discovered a new form of natural camouflage.
Using a combination of behavioral tests in the field and computer visual modeling, the researchers identified one curious feature. According to their article published in PNAS, although the transparency of the glass frog acts as camouflage, its mechanism differs from the mechanism of “real” transparency of objects.
Lead author Dr. James Barnett explained: “Frogs are always green but appear lighter and darker depending on the background. This change in brightness makes frogs less visible 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 that when they are pressed to the side of the frog at rest, there is a diffuse gradient from leaf color to frog color, without pronounced sharp edges. This circumstance suggests a new form of camouflage: “diffusion at the edges.”
Dr. Barnett noted that scientists are often skeptical during scientific debates about how “transparent” glass frogs can actually be called.
“Transparency is, in fact, the perfect camouflage. It occurs in aquatic species relatively rare and occurs when animal tissue has the same refraction rate as ambient water. However, in air and tissue refraction rates vary quite strongly, so transparency in terrestrial species with transparency should be worse. Indeed, transparent earthly beings are extremely rare. Although glass frogs are one of the most commonly cited examples of “terrestrial” transparency, their rare green pigmentation means it is better to describe these animals as translucent,” he concluded.