Spiky-Skulled Frogs Head-Butt Enemies to Deliver Deadly Toxins

Aparasphenodon brunoi (Bruno's Casque-headed Frog). (Credit: Carlos Jared/Butantan Institute) Two species of highly toxic frogs have a bone to prick with their predators. Corythomantis greeningi and Aparasphenodon brunois frogs, native to Brazil, have skin secretions that are more deadly than the venom of pit vipers. A single gram of A. brunois secretions could kill 80 humans. But unlike poisonous amphibians, these frogs have an additional trick up their sleeve: They have spikes growing on their skulls, and when danger is near, they head-butt predators to ensure the toxic payload hits its mark.