Why do some frogs have poison in their skin?

Many frogs and toads defend themselves by secreting irritating or poisonous compounds from their skin. In poison dart frogs, some of the most potent toxins come from chemicals in their prey, especially certain insects and mites, and are then stored in the skin. This makes bright coloration a warning signal to predators. Other amphibians produce their own defensive compounds through skin glands. The strategy is effective because predators learn quickly to avoid animals that are toxic or taste bad.