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Venomous Brazilian Frogs Discovered; Skin Secretions 'More Venomous Than Deadly Pit Vipers'

Aug 06, 2015 06:58 PM EDT
Aparasphenodon brunoi is one of two venom-headed frogs recently discovered in Brazil
Although this frog looks benign and big-eyed, few predators could feast on it, because its head emits venom.
(Photo : Carlos Jared/Butantan Institute)

Don't lick a frog, you may have been told by a hyper-vigilant parental figure. Also, don't touch that poisonous snake. But those were two separate admonitions, right? Because, yes, many frogs secrete poison from skin glands – but most of them don't have venom. 

But researchers from Utah State University and Instituto Butantan in São Paulo, Brazil recently published their research in Current Biology about two types of frogs in Brazil, Corythomantis greeningi and Aparasphenodon brunoi, that have skin secretions more venomous than those of deadly pit vipers.

"A poisonous animal has toxins that must be inhaled or ingested by another animal to cause harm," says biologist Edmund "Butch" Brodie, Jr., in a statement. "To be described as venomous, the organism must have a delivery mechanism -- such as hollow fangs in vipers – to introduce its toxins into other animals."

While those two frogs have been known for decades, or possibly centuries, scientists have known little of their biology. Essentially, scientists were not aware that the frogs had bony spines on their heads that delivered venomous secretions into another animal, a release said.

While researcher Carlos Jared was collecting the frogs for research, his hand touched one of the frog's spines and he felt intense, radiating pain for about five hours, noted the release.

"This action should be even more effective on the mouth lining of an attacking predator," Jared said in the release. Fortunately, that frog was the less toxic of the two. For instance, the researchers have calculated that one gram of the toxic secretion of the other frog species, A. brunoi, would be sufficient to kill 300,000 mice or 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 said in the release. However: "We don't know of any animal that successfully feasts on these frogs," the USU professor said in the release. "Nothing can get past the head spines."

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