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Shape-shifting 'punk rocker' frog goes from spiny to smooth in minutes

Shape-shifting 'punk rocker' frog goes from spiny to smooth in minutes


Pristimantis mutabilis is the first recorded amphibian with the ability

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Pristimantis mutabilis doing its thing.
Pristimantis mutabilis doing its thing.
Zoological Journal of the Linnean Society)

When researcher Katherine Krynak and her husband Tim spotted an unknown species of frog in a misty cloud forest in Ecuador, they did what any good scientists would do — they scooped it into a cup for further examination the next morning. The frog was tiny (no more than 23 millimeters in length) and covered in thorn-like spines that led the Krynaks to christen it the "punk rocker" frog.

had they got the wrong frog?

However, when they tipped the animal out onto a sheet of plastic the next morning to be photographed, they saw that its skin was entirely smooth. They were disappointed, and assumed they'd picked up the wrong frog by mistake.

"I then put the frog back in the cup and added some moss," says Katherine, a PhD student at Case Western Reserve University in Ohio. "The spines came back... we simply couldn't believe our eyes, our frog changed skin texture! I put the frog back on the smooth white background [and] its skin became smooth."

Pristimantis mutabilis before and after its transformation. (ASA)

The Krynaks had discovered what is believed to be the first known amphibian with ability to change the texture of its skin. The frog has been named Pristimantis mutabilis or the mutable rainfrog, and is described for the first time as a new species in the most recent issue of the Zoological Journal of the Linnean Society. It takes just five minutes for its skin to change texture, and Katherine says the unusual ability probably helps the frog hide from birds and predators in Reserva Las Gralarias, the Ecaudorian nature reserve where the frog was found and where the Krynaks both volunteer.

"the spines and coloration help them blend in."

"The spines and coloration help them blend into mossy habitats, making it hard for us to see them," said Katherine in a press release from Case Western University. "But whether the texture really helps them elude predators still needs to be tested." It's also not clear how exactly mutabilis changes its skin texture.

Pristimantis mutabilis isn't a lone mutant though. After the frog was documented back in 2009, researchers working at the same reserve discovered that Prismantis sobetes, a previously known species and a relative of mutabilis, had the same ability. A spiny member of the species was observed turning smooth when placed on a sheet to be photographed, and researchers are now wondering how many frog species have been wrongly classified thanks to this shape-shifting ability.

The Pristimantis genus, for example, contains over 470 species. It's possible that some of these are actually the same frog discovered twice.