Detailed Explanation:

Answer: Option 3 — All three

All three groups mentioned in the question—butterflies, fish, and frogs—have poisonous species among them. Butterflies like the Monarch sequester toxins from their larval diet of milkweed, making them poisonous to predators. Many fish species such as pufferfish, lionfish, and stonefish possess deadly venom or toxins. Poison dart frogs are classic examples of amphibians that secrete potent toxins through their skin as a defense mechanism.

📝 Short Notes: Poisonous Species in Different Animal Groups

• Poisonous Butterflies: Monarch butterflies accumulate cardiac glycosides from milkweed plants during their caterpillar stage, making them toxic to birds and other predators. Other examples include the Pipevine Swallowtail.
• Poisonous Fish: Pufferfish contain tetrodotoxin, a neurotoxin deadly to humans. Lionfish and stonefish have venomous spines. Stingrays possess venomous barbs on their tails.
• Poisonous Frogs: Poison dart frogs (family Dendrobatidae) of Central and South America secrete alkaloid toxins through their skin. The Golden Poison Frog is one of the most toxic vertebrates on Earth.
• Mechanism of Toxicity: Some species produce toxins endogenously (within their bodies), while others sequester them from their diet (like Monarch butterflies and poison dart frogs).
• Purpose of Poison: These toxins serve primarily as defense mechanisms against predators, advertised through warning coloration (aposematism) in many cases.