Venomous Brazilian Frogs Discovered To Be World’s First

A pair of Brazilian frog species have been identified as the world’s first-known venomous frogs. Of course, some frogs are known to secrete poison from glands in their skin. But, not only do these Brazilian frogs produce potent toxins, they also have a method to deliver their deadly secretions into another animal using bony spines on their heads.

The frogs, Corythomantis greeningi and Aparasphenodon brunoi, have both been known for many decades, if not centuries. But scientists have known little of their biology. The frogs have no known predators, which now makes perfect sense considering these latest findings.

Says Edmund Brodie, Jr. of Utah State University:

“Discovering a truly venomous frog is nothing any of us expected, and finding frogs with skin secretions more venomous than those of the deadly pit vipers of the genus Bothrops was astounding.”

The researchers calculate that a single gram of the toxic secretion from one of frog species, A. brunoi, would be sufficient to kill more than 300,000 mice or about 80 humans.

“It is unlikely that a frog of this species produces this much toxin, and only very small amounts would be transferred by the spines into a wound,” Brodie says. “Regardless, we have been unwilling to test this by allowing a frog to jab us with its spines.”

Next, the researchers plan to better understand the venom and the skin glands that produce the venom. Brodie and Jared say they’ll also be studying several other frog species from around the world, which they also suspect to be venomous.

Carlos Jared, Pedro Luiz Mailho-Fontana, Marta Maria Antoniazzi, Vanessa Aparecida Mendes, Katia Cristina Barbaro, Miguel Trefaut Rodrigues, Edmund D. Brodie Jr.
Venomous Frogs Use Heads as Weapons
Current Biology DOI:

Photo: Aparasphenodon brunoi (Bruno’s Casque-headed Frog). Carlos Jared/Butantan Institute