A researcher discovered the hard way that Brazil has two frog species more venomous than pit vipers

Most people know some frogs have poisonous skin. But even frog experts can still be surprised by how nasty the cute amphibians can be.

Experts such as Carlos Jared, from Instituto Butantan’s cellular biology laboratory, who picked up a Greening’s frog like this one on a recent field trip to Caatinga in the state of Rio Grande del Norte:

Greening’s frog. Unlickable. Picture: Carlos Jared/Butantan Institute

“Intense, immediate pain radiated up his arm and lasted five hours,” Edmund Brodie of Utah State University said in a statement following the release of a study on the frog yesterday. “He was many hours from any medical services, so just toughed it out.”

Jared was lucky he didn’t touch the other frog in the study – Bruno’s casque-headed frog. Don’t touch this one either:

Bruno’s casque-headed frog sees you, isn’t scared. Picture: Carlos Jared/Butantan Institute

The study, in the most recent issue of Current Biology found that a single gram of venom from Bruno’s casque-headed frog (Aparasphenodon brunoi) can kill 80 people.

On science’s venomous ratings charts, that’s equivalent to 300,000 mice, which makes it 25 times more poisonous by weight than that of Brazilian pit-vipers.

And here’s what makes them so different from the brightly coloured frogs you might be familiar with whose skin is used to supply the poison for poison darts. Both Bruno’s and Greening’s frogs have spines on their lips which inject the venom directly into whatever’s threatening them.

So not only are they more venomous than many snakes, they’re actually a lot like snakes, except they can also jump.

When Jared got 15 frogs from each species back to the lab, he also found another unique trait – they can wiggle their heads up, down and side-to-side.

Juan Santos of Brigham Young University in Utah said that, and the presence of spines suggests some frogs “might actively rather than passively defend themselves against attackers”.

So while it’s not easy being green, frogs aren’t entirely helpless.

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