Image Credit: Albertina Pimentel Lima
Somewhere in the middle of the Amazon rain forest in South America is a strange kind of frog (Lithodytes lineatus) that appears to be completely impervious to aggressive leaf-cutter ants, and until now, it wasn’t understood why the little insects leave this particular species alone while buzzing down everything else in their path.
Reporting in the journal Behavioral Ecology and Sociobiology, researcher André Barros and his colleagues explain the frog’s innate ability to excrete a type of chemical from its skin that normally only the leaf-cutter ants excrete.
The ants usually use this chemical as a pheromone marker to determine who’s friendly and who’s a foe. As a result, all the ants use this chemical to tell each other apart from another species.
This frog, on the other hand seems to have evolved with a way to mimic that very same chemical. As a result, its effects work similarly to camouflage because it allows the frog to ‘fit in’ as a friend to the ants.
Confirming the chemical’s properties, the researchers put the Lithodytes lineatus into a glass vessel along with a load of leaf-cutter ants and a few other frog species from the region.
Unsurprisingly, the Lithodytes lineatus never made any attempts to escape the vessel during the ten-minute exposure, but all of the other frog species were jumping around trying to find an exit.
To further prove that the chemical worked as a protection, they covered 10 frogs that don’t secrete the chemical naturally with it to see what would happen. Unsurprisingly, even the other species of frogs that were now lathed in the chemical bath were no longer affected by the ants.
"Our results demonstrate that the skin of frog Lithodytes lineatus has chemicals that prevent the attack of two species of leaf-cutting ants," says Barros. "It therefore seems that Lithodytes lineatus has chemical skin compounds that are recognized by ants of genus Atta, which may allow for coexistence between ants and frogs."
Since the frogs rely on the humidity of the area, chances are they evolved to perform this trick so they could better survive and reproduce.