First known venomous frogs stab with toxin-dripping lip spikes
Brazilian amphibians carry venoms more deadly than those of pit vipers
WORST HEAD-BUTT When this yellow-skinned frog curls back its plump upper lip, bony spikes underneath stab toxins into foes.
Carlos Jared/Butantan Institute
Carlos Jared discovered the first known venomous frog by accident. And it took him a long time to connect his pain with tree frogs that head-butted his hand.
Jared, now at the Butantan Institute in São Paulo, got his first hint of true venom when collecting yellow-skinned frogs (Corythomantis greeningi) among cacti and scrubby trees in Brazil’s dry Caatinga region. For hours after grabbing the frogs, intense pain radiated up his arm for no obvious reason.
He knew frogs have no fangs to deliver toxin. Many frog species can poison an animal that touches them, but they’re poisonous. True venomous animals actively deliver toxins.
Jared realized head-butting delivers venom only when he saw the frogs’ upper lips under a microscope. Bone spikes erupted near venom glands that looked “giant,” he says. As a frog’s lips curl back, glands dribble toxins onto spikes sticking out
