Can’t Touch This!
We already know there are colorful poisonous frogs leaping about the foliage of many rainforests around the world. Most frogs and toads are poisonous, holding distasteful and/or poisonous secretions on their skin to help deter predators. Now, there are two documented species found to inject poison which makes them the first known venomous frogs. When disturbed, spines protruding from their skulls inject deadly venom directly into the victim’s bloodstream.
Both frogs were discovered in Brazil. The Greening’s frog (Corythomantis greening) carries toxin about twice as lethal as that of a pit viper. The Bruno’s casque-headed frog (Aparasphenoden brunoi) is even more deadly, approximately twenty-five times more venomous by weight than that of the pit viper!Calculations by researchers have suggested that a single gram of toxin from the Bruno’s casque-headed frog is enough to kill about 80 humans. To be considered venomous, a creature needs to play an active part in delivering toxins into the victim. In both cases of the Brazilian frogs, venom is injected using spines that jut from the top of their heads. Special glands grow from the skull and secrete toxic mucous. According to researchers, the chemical composition from both species were very similar. The analyses found hyaluronidase, a protein that is usually found in the venom of snakes. Hyaluronidase helps in the spread of toxins. This is the first report of such a substance in amphibian skin secretions. Researchers believe there could be predators within the same forest that are resistant to these toxins.
These toxic frogs choose to live in holey rocks or trees and close the opening with their head, maintaining the humidity inside their hole and reducing water loss from their body.
“The presence of these spines suggests that at least some other tree frogs might actively, rather than passively, defend themselves against attackers. This research will open a new line of research into the evolution of anti-predator mechanisms in frogs,” states Juan Santos of Brigham Young University in Utah.
--Mi
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