Consider the following: 1. Butterflies 2. Fish 3. Frogs. How many of the above have poisonous species among them?

All three groups contain poisonous species. Many butterflies, like the Monarch, are poisonous because they sequester toxic compounds (cardenolides) from milkweed plants they eat as larvae. Numerous fish species are poisonous, including pufferfish (containing tetrodotoxin) and several reef fish. Poison dart frogs of South America are among the most toxic animals on Earth, producing potent alkaloid toxins through their skin. Hence all three categories include poisonous species.