Thousands of animal species use toxic chemicals to defend themselves from predators. Snakes have blood clotting compounds in their fangs, the bombardier beetle has corrosive liquid in its abdomen and jellyfish have venomous, harpoon-like structures in their tentacles. But how do these animals survive their own poisons? Rebecca D. Tarvin details the strategies that protect animals from themselves. Lesson by Rebecca D. Tarvin, animation by Giulia Martinelli.