Biology Without Borders

The Shape Shifting Frog

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Camouflage is a very important tool for those animals wanting to escape predators. There are some animals that have complex forms that make them harder to discern from their environment, such as stick-insects. Others can quickly change their colours to match their background, such as the ocotopuses. Now two researchers, Katherine and Tim Krynak, have found a new species of frog that can change its skin texture to mimic the surface it is standing on.

This incredible frog was found in 2009 at the Reserva Las Gralarias in Mindo, Ecuador. Located on the western slope of the Andes, this cloud forest was turned into a reserve to help preserve the endangered birds of the region. They caught the spiky-backed frog while surverying the area, then they put it in a cup filled with moss and brought it back to camp to photograph. It was to their great surprise that when the frog was placed on a smooth surface for its photoshoot, its skin wasn’t spiky anymore, it was just as smooth as the surface. The frog could change its skin texture in about three minutes.

Image taken from Zoological Journal of the Linnean Society. It shows the frog’s change in skin texture from spiky to smooth in over 5 minutes.

For the next three years, the frogs were studied in the Universidad Tecnológica Indoamérica in Ecuador and it was found to be a new species, which was named Pristimantis mutabilis. Further research showed that Pristimantis sobetes, another frog with similar markings but much larger than P. mutabilis, also had this shape shifting trait. P. sobetes is the only relative tested so far.

This find is very exciting for herpetologists, not only because of this recently discovered trait in frogs but also because it challenges old descriptions of other frog species (especially other rain frogs) that may have been identified by few preserved specimens. This is also a surprising new trait for the zoology community, never before seen in amphibians. The researchers want to continue their work by investigating if these two species of Pristimantis evolved independently their skin texture trait or inherited it from a common ancestor, also if other Pristimantis frogs also have this trait.

Reference:

Guayasamin, J. M., Krynak, T., Krynak, K., Culebras, J. and Hutter, C. R. (2015), Phenotypic plasticity raises questions for taxonomically important traits: a remarkable new Andean rainfrog (Pristimantis) with the ability to change skin texture. Zoological Journal of the Linnean Society, 173: 913–928. doi: 10.1111/zoj.12222

(the link may be broken so here it is directly: http://onlinelibrary.wiley.com/doi/10.1111/zoj.12222/full)

Henrique Ramalho Martins

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