When faced with the threat of being gobbled up by hungry predators, the ability to seamlessly blend in with the environment is crucial for survival. Some animals have evolved appearances strikingly similar to things in the environment, like stick insects or stonefish, whereas others can quickly change color to match the background, such as chameleons and cuttlefish. Now, adding to this awesome list of copycats, scientists have discovered a species of frog that is able to change its skin texture in order to mimic the surface it is perched on.
Interestingly, although this unique skin-morphing ability does not appear to have been reported in amphibians before, shortly after this frog was found, colleagues of the discoverers noticed that a close relative already known to science also shares this talent, but scientists never noticed it before. The new frog and its skills have been described in the Zoological Journal of the Linnean Society.
The species was discovered by a duo of researchers, Katherine and Tim Krynak, whilst they were exploring a nature reserve in Ecuador’s western Andean cloud forest back in 2009. Having regularly surveyed animals living in the reserve for a number of years, the pair immediately suspected that an unfamiliar spiny frog perched atop a mossy leaf was a previously unknown species. They caught the marble-sized animal, which they nicknamed “punk rocker” due to its spiky skin, and brought it back to photograph.
But when they placed the tiny frog onto a smooth sheet for its photoshoot, they were startled to see its skin was completely smooth. Unsure as to whether they had collected the right animal, the frog was returned to its cup, which they had filled with moss. Amazingly, the animal quickly assumed its previous spiky appearance.
“The spines came back… We simply couldn’t believe our eyes, our frog changed skin texture,” Katherine Krynak said in a statement. “I put the frog back on the smooth white background. Its skin became smooth.”
Krynak explained that although the frog’s combination of spines and coloration clearly help it blend into mossy backgrounds, whether the texture-changing ability truly helps the species evade predators is unknown at this stage. Colleagues back at Universidad Tecnológica Indoamérica then spent the next few years characterizing the frog, which revealed that it can change its texture in around three minutes. Morphological and genetic analysis also confirmed that the animal is new to science, so it was later named Pristimantis mutabilis, or the mutable rainfrog.
Further investigation then led members of the research team to discover that a close relative of the frog, P. sobetes, also shares this skin-morphing ability, raising the possibility that other Pristimantis frogs may also be capable of the same trick. This could have implications for how the species have been identified in the past given it is now a possibility that one species could have been mistakenly described as two.
The researchers would like to continue their work by further characterizing the animals and investigating whether these two species independently evolved this trait or inherited it from a common ancestor.