Kiss This Frog and It Becomes a Killer, Not a Prince

With all the beautiful people in Brazil, there would seem to be no need to kiss a frog in hopes of getting a handsome prince to go to the Carnival with. Now it turns out that foolish decision could be a deadly one as well. Researchers in Brazil have discovered the world first (and second) venomous frogs that deliver a deadly poison via a kiss from their froggy lips.

Yes, we already know of some frogs that are poisonous, like the Oophaga sylvatica or diablito (little devil) of Colombia and Ecuador. However, the diablito must be eaten to deliver its toxins – a fatal move for both frog and victim.

On the other hand, Greening’s frog (Corythomantis greeningi) and Bruno’s casque-headed frog (Aparasphenodon brunoi) are the only known venomous frogs, meaning they inject their toxins into their victims via bites, stings or, in their case, tiny spikes on their heads and upper lips.

According to an article in the latest edition of Current Biology, both of these species have been known since the 1800s and were considered to be nontoxic … until teams conducting new studies on the found that the intense pain in their palms was the result of handling the frogs. The venom was injected into their skin via tiny spines on the frogs’ heads and upper lips.

Before you call the researchers wimps for crying about a little skin pain from itty bitty frogs, they measured the potency of the toxins and found that one gram of venom from Bruno’s casque-headed frogs could kill 80 people or 300,000 mice. This venom is 25 times more poisonous by weight than that of Brazilian pit-vipers. Venom from Greening’s frog is only twice that of a pit-viper, but – on the post-kiss-dead-or-alive scale – it still has some pretty lethal lips.

It’s a good practice to avoid kissing any kinds of frogs but, if you must, avoid doing it in Brazil’s Caatinga region where the Greening’s frogs live or the Atlantic Forest where Bruno’s casque-headed frogs leap.