Although many frogs and toads are known to be poisonous, i.e. deadly if their toxins are ingested, two frogs from Brazil are now known to be venomous as well, delivering their toxins through spines and spikes on their heads, a first for the four legged amphibians. Scientists that made the discovery said calculations suggest that a single gram of the venom from the more toxic species, Aparasphenodon brunoi, could kill more than 300,000 mice or about 80 humans.

The strength of toxicity of the skin secretions is remarkable, and to say we were surprised by that is an understatement," Brodie said. "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. It moves the study of amphibian defenses to a new level.

Although their venom packs a wallop, scientists are convinced it is only used as a defensive mechanism as opposed to using it to hunt their prey. Since neither frog has any known predators, that is certainly a likely scenario.

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Photo: Carlos Jared/Butantan Institute