Texture-morphing frog discovered in Ecuador

In a paper published in late March, researchers identified a new frog species along with a new way of considering vertebrate camouflage. The species, Pristimantis mutabilis, was first discovered in the Ecuadorian rainforest in 2006.

At the time, it wasn’t recognized as a foreign species; the team took some pictures but brought no specimens back with them, and it was not until 2009 that a live specimen was obtained.

The frog was initially overlooked because it so closely resembled discovered species (except for its abnormally bumpy skin).

Three years after the initial sighting, amphibian biologist Katherine Krynak returned to the scene to capture a live specimen. However, upon returning to camp — frog in hand — Krynak found its skin a typical smooth texture, not at all resembling the spiky appearance that had so enthralled the team.

“And I’m so mad at myself because I’m the one that captured it and put it in the cup,” Krynak told Wired writer Matt Simon. “How could I have possibly picked up the wrong frog?” As it turned out, Krynak hadn’t made a mistake: Pristimantis mutabilis was, at the time, the only known vertebrate that can change the texture of its skin as a camouflage mechanism.

Several well-known invertebrates (most famously the octopus) are able to adjust both the color and texture of their epidermis to better blend with surroundings. As it turns out, this ability is not unique to those animals lacking a backbone.

Octopuses and cuttlefish adjust their skin texture using a series of miniscule muscles to control papillae (structures like the bumps on a human tongue) all along the animal’s body.

The process is like voluntary goose bumps. According to Krynak, the mechanism used by P. mutabilis is not known, and could be completely different from that commonly used by invertebrates.

After the discovery of P. mutabilis and its camouflage trick, Krynak’s co-authors unearthed a second breakthrough: another species of frog — discovered 30 years ago — has the same ability. The texture-morphing skill in P. mutabilis’ cousin, Pristimantis sobetes, had gone unnoticed for all those years.

Though both frogs inhabit the same genus, they share it with some 500 other species, none of which share the ability (as far as scientists have documented).

Conservation biologists are working to enable further discoveries in the frog realm, but there are challenges in many habitats like Ecuador’s rainforest, the home of P. mutabilis. According to Robin Moore, a conservation biologist for the Amphibian Survival Alliance, habitat loss is the single greatest threat to amphibians.

“In Ecuador,” Moore says, “you have mining, you have agriculture, you have cow pastures… and forests continue to be cut down.” Each of these factors poses a threat to local amphibians and particularly those that, like frogs, have small habitat ranges.

A small range may sound like a death sentence when habitats face the challenges posed by industry, but Moore takes a more optimistic view.

“You can protect relatively small tracts of habitat and essentially save a species,” he says. The task of preservation becomes even easier, thanks to species like P. mutabilis, which has been affectionately nicknamed the “punk rocker frog.” P. mutabilis is a charismatic, or flagship, species: the conservation biologist’s dream.

Flagship species attract attention from the general public; they’re the poster children of conservation movements and often enable conservationists to protect their habitats simply through the intrigue they inspire in the public.

“I think when people realize they have a unique species, it does instill that sense of pride,” Moore said. “For me that also sort of lends weight to a discovery like this.”