First venomous frogs

While poisonous frogs that secrete toxins through their skin have long been known about, the first venomous frogs were only documented in 2015. Two Brazilian hylid frogs – Greening's frog (Corythomantis greeningi) and Bruno's casque-headed frog (Aparasphenodon brunoi) – were both found to possess small bony spines on their heads which, via "headbutting", enable them to inject venom into would-be attackers. The findings were published in the journal Current Biology on 6 August 2015.

Greening's frogs have largest skin glands and so are capable of producing more toxic secretions, however Bruno's casque-headed frogs' venom is more potent. The former's venom is double the toxicity of Brazilian pitviper snakes (genus Bothrops), such as the notorious fer-de-lance, while the latter's is 25 times more toxic by weight; the researchers estimate that just 1 g (0.04 oz) of venom from the Bruno's casque-headed frog would be enough to kill 80 adult humans or 300,000 mice.

The study was a collaboration between the Instituto Butantan, the Universidade de Sao Paulo (both Brazil) and Utah State University (USA), led by Dr Carlos Jared of the Instituto Butantan.