These frogs’ heads are venomous weapons

According to Live Science, the venomous frogs discovered in Brazil were observed using their poison offensively, rather than strictly as a defense mechanism, as a poisonous frog would.

Skull of a Corythomantis greeningi, (Greening’s frog), showing spines. You can not see the spines well in this photo, but check out page 8 of this document to see how the frogs’ heads are armed with an injury-inflicting surprise for anyone who messes with the amphibians. Unfortunately for Jared, he first realized that C. greeningi might be venomous firsthand while collecting frogs for research.

The researchers calculated that a single gram of the venom from Bruno’s casque-headed frog is more potent than that of deadly pit vipers.

The work of Brodie and his colleagues in Brazil was published in the journal Current Biology this week.

Of course, there are hosts of brightly colored frogs with toxin-producing skin glands.

The frogs in question, Corythomantis greeningi and Aparasphenodon brunoi, have both been known for many decades, if not centuries.

As described in the new paper, C. greeningi, a species that prefers dry and rocky environs, delivers venom twice as toxic as a pit viper. In comparison, the venom of the deadly Brazilian Bothrops pit vipers is half as lethal as that of Corythomantis greeningi and 25 times less risky as that of Aparasphenodon brunoi.

Meet the two species that just happen to be the world’s first, and so far only venomous frogs. “Amphibians have a wide array of skin toxins that have been well-studied, but this sort of mechanism – transmitting the toxin as a venom – has not been found before”.

Tests on the other frog, A. brunoi, which also has a set of spines coming off the front of the skull, showded that it produces a toxin which is even more toxic, with one gram capable of killing more than 300,000 mice or about 80 people. But unlike poisonous amphibians, these frogs have an additional trick up their sleeve: They have spikes growing on their skulls, and when danger is near, they head-butt predators to ensure the toxic payload hits its mark.

It has long been known that some frogs secrete venom out of their skin, but two frogs have taken this phenomenon to a whole new level by using their heads as venomous weapons.

Neither of the frogs is known to have any natural predators, the authors said – a fact that makes ideal sense in light of their unexpected discovery.

This suggest frogs are not as harmless as we think, says Juan Santos of Brigham Young University in Utah.

The researchers are now investigating several other frog species from around the world that they also suspect are venomous.