‘Punk Rocker Frog’ Has Shape-Shifting Spikes and Teen Angst

The punk rocker frog can shape-shift its skin to blend in with its surroundings. Here it is in its weekend garb at left, and business casual at right.

Amphibian biologist Katherine Krynak was trekking through the rainforests of Ecuador in 2006 when her expedition encountered a tiny frog, about the size of your thumbnail. You wouldn’t have called it particularly extraordinary, but still, they snapped some photos. Back at camp, the team blew the shots up on a big screen, and saw something super weird: The frog had a bizarrely bumpy, almost spiky, texture to its skin. Turns out they had a species new to science—and unfortunately they’d left it behind.

It took three years before Krynak could return to Ecuador and secure a live specimen. This time, they dropped their frog in a cup and took it back to camp. But when they went to remove it, to their crushing dismay, it looked like your average smooth-skinned frog. “And I’m so mad at myself because I’m the one that captured it and put it in the cup,” Krynak recalls. “I was like, how could I have possibly picked up the wrong frog?” Devastated, she dropped some moss in the cup because she “just wanted to make him more comfortable,” and walked away.

Returning a few minutes later, Krynak discovered something incredible: The frog was spiky again. It was apparently changing the texture of its skin to better blend in with its surroundings, and that’s very weird indeed for a vertebrate. Highfalutin invertebrates like the cuttlefish, sure, all the time they’re transforming both the color of their skin and its texture. But not vertebrates. So not only had Krynak found herself a new species, but a new species that changed how scientists think about amphibian camouflage. In a paper published Tuesday, she dubbed the spiky wonder Pristimantis mutabilis, known informally as the punk rocker frog. It’s the [insert your favorite punk star here so I don’t have to pick one and get angry emails about my choice] of the rainforest.

Now, if you’re a relatively helpless creature like a frog, you have a few options for adaptations so you don’t die all the time. Some frogs excrete toxins through their skin, like the famous poison dart frogs, which don’t even bother blending in. In fact, they to present flashy colors to wink-wink-nudge-nudge at predators that they should avoid them. Others try mimicking their surroundings. That seems like what the punk rocker frog is doing, morphing its skin over the course of a few minutes when it finds itself on, say, moss, in order to fool predators (though researchers have more testing in front of them to confirm this).

According to Krynak, how exactly the frogs change their skin texture is unclear. For all they know, it’s a totally different method than the one cephalopods use, but it’s worth mentioning that cuttlefish and octopuses can change the texture of their skin because of tiny structures called papillae distributed all over the creature’s body. These structures are controlled by tiny specialized muscles, some of which are arranged horizontally, and others in concentric circles. The circular muscles push the tissue up, while the horizontal ones give the papillae its shape, which can look a bit like a ping-pong paddle. So it may be the punk rocker frog is using a muscular trick somewhere along these lines.

Pristmantis sobetes, the other species of skin-morphing frog.

But this tale gets even stranger. After Krynak’s discovery, some of her co-authors found that another frog already known to science for three decades had the same shape-shifting ability, which its discoverers had missed at first. While both of these shape-shifting frogs are in the same genus (Pristimantis), so are another 500 or so other species, and none of them can morph.

What could be going on here? “There’s this really cool evolutionary story here,” says Krynak, “these two species are related, but are of two differing groups of frogs, so we have either convergent evolution happening,” that is, the two frogs have developed the shape-shifting ability independently, “or it could be that all of the frogs in the genus at one point had the skin-morphing ability, then for whatever reason lost the trait,” though Krynak finds that unlikely. “Or it could be that many of the other species out there that are closely related actually have this trait, and we just haven’t documented it yet.”

And that’s the really exciting bit. Could there be a whole slew of punk frogs in South America that can pull off this remarkable behavior, going to shows and yelling at each other or whatever it is punks are supposed to do? And they don’t even need to be in the same Pristimantis genus—people just generally know so very little about frogs, in South America or elsewhere. I mean, clearly, even when we catch and describe them the first time around like scientists did with the first species 30 years ago, the shape-shifting is something that’s easily missed. So it’ll be interesting to see what research comes out of those jungles in the coming years.

That is, if we don’t wipe the frogs off the planet first.

Protecting a Punk Rock Superstar

Frogs are in serious trouble worldwide, with half of all species at risk of extinction. Part of the problem is a nasty, hypervirulent fungus known as chytrid. It attacks a frog’s skin—which the frog relies on to absorb moisture and vital salts—often wiping out whole populations.

But according to Robin Moore, a conservation biologist at the Amphibian Survival Alliance, that’s not the biggest threat. Habitat loss is. The fungus already has ripped through Ecuador, and the frogs that have survived so far still have to put up with the country’s many industries. “So in Ecuador you have mining, you have agriculture, you have cow pastures,” says Moore. “And forests continue to be cut down.”

The problem is, frogs tend to have small distributions: Lose a single stream system and a species can vanish forever. Ironically enough, though, this can make conserving frogs easier. “You can protect relatively small tracts of habitat, and essentially save a species,” says Moore.

The punk rocker frog’s habitat. No wonder the things are hard to find. It’s all, like, foggy and stuff.

It’s just a matter of getting the land preserved, and that’s where the punk rocker frog could come in. While Krynek found it on a preserve, it’s only 1.6 square miles of rainforest, and no one knows how far the frog ranges beyond that land, if it does at all. But conservationists love flagship species, an iconic critter that gets folks interested in saving a habitat at large. Think tigers or bald eagles or pandas. Up in Costa Rica, it was the golden toad, which conservationists sadly were unable to save from extinction, but its beauty and charisma made the toad a posthumous celebrity. Accordingly, a preserve was established in its erstwhile territory.

Could the bizarre punk rocker frog do the same for Ecuador? “These kinds of species can be flagship species for the conservation of an area,” says Moore. “I think when people realize they have a unique species, it does instill that sense of pride. So I think for me also that sort of lends weight to a discovery like this.”

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