LOGAN, Utah, Aug. 6 (UPI) -- Until recently, there were no venomous frogs. There are plenty of poisonous frogs -- amphibians that cause harm when they or their secretions are ingested or absorbed through contact.
To be venomous, a creature must inject its poison. And according to new research, there are two species of helmeted tree frogs in Brazil that do just that, delivering their toxins via head-butts.
They're the Zinedine Zidanes of the frog world.
Sharp spines, well-supplied poison glands and the ability to turn their heads allow the two frog species -- Corythomantis greeningi and Aparasphenodon brunoi -- to proactively defend themselves from their enemies.
"Unlike many frogs, these species can actually turn their heads. They use this motion to defend themselves with their head spines," Utah State University biologist Edmund "Butch" Brodie, Jr., said in a press release. "This is one of those 'once in a career' discoveries. It's really strange and bizarre."
The work of Brodie and his colleagues in Brazil was published in the journal Current Biology this week.
As described in the new paper, C. greeningi, a species that prefers dry and rocky environs, delivers venom twice as toxic as a pit viper. The slimy-skinned A. brunoi, which sports orange and brown coloration and prefers the humidity of the rain forests, boasts an ultra deadly venom -- 25 times stronger than a viper's toxins.
"We don't know of any animal that successfully feasts on these frogs," Brodie said. "Nothing can get past the head spines."
Researchers don't yet know the exact composition of the two frogs' venom, but say they've identified a number of enzymes similar to those that make up spider and snake venom.