Poisonous frogs are not something new to scientists. Most amphibians such as salamanders, newts and frogs have skin glands which produce poison in order to ward off predators. Researchers have now discovered that in the wilds of Brazil there are two species of venomous frogs, the first ones which science has ever known. These species do not only secrete poison, but they are also provided with weapons destined to deliver the poison.
More details about the two venomous species, Corythomantis greeningi and Aparasphenodon brunois, were published in the journal Current Biology. These species have bony spines on the back of their heads, their jaws and their noses. When they are grabbed the frogs release venom from the skin glands around their spines and rub the spines into whatever grabbed them. They have very flexible legs for frogs and they can flex their heads.
According to the research team one gram of venom from Aparasphenodon brunoi could kill over 300.000 mice and nearly 80 humans. On the other hand one gram from Corythomantis greeningi could kill over 24.000 mice and six humans. It seems that in spite of the fact that Corythomantis greeningi’s venom is less toxic the frog has larger skin glands and larger head spines and thus it can produce more venom than Aparasphenodon brunoi.
The research team also discovered that compared to the venomous Brazilian Bothrops pit vipers that are deadly the venom of Corythomantis greeningi is twice as lethal and the venom of Aparasphenodon brunoi is 25 times more dangerous.
The scientists discovered the venomous frogs the hard way, when the lead author of the study Carlos Jared from the Butantan Institute in São Paulo touched the head of the frog Corythomantis greeningi and injured his hand on the bony spines. He was lucky that this was the less venomous species among those two, but he still experienced intense pain on his arm which lasted for five hours.
The co-author of the study herpetologist Edmund Brodie, Jr. from Utah State University in Logan remarked:
The strength of toxicity of the skin secretions is remarkable, and to say we were surprised by that is an understatement. 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.”
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