Consider the following:
- 1.Butterflies
- 2.Fish
- 3.Frogs
How many of the above have poisonous species among them?
Answer & explanation
Answer: (c) All three
Each group includes species that are toxic to eat or touch, a defence that makes predators avoid them. The monarch butterfly stores a poison from the weed its caterpillar eats, many pufferfish carry the deadly nerve toxin tetrodotoxin, and poison frogs secrete toxins through their skin.
- ✓ 1. The monarch butterfly is distasteful and harmful to birds because of a chemical it takes in as a caterpillar feeding on a poisonous weed.
- ✓ 2. Pufferfish carry tetrodotoxin, a potent neurotoxin usually concentrated in the ovaries, liver, intestine and skin; it is not destroyed by cooking, and eating badly prepared fish can be fatal.
- ✓ 3. NCERT notes that some frogs are poisonous and are therefore left alone by predators; the brightly coloured poison dart frogs of Central and South America are the best-known case.
Remember · Poisonous = harmful when eaten or touched (monarch butterfly, pufferfish, poison dart frog); venomous = injects toxin (snake, scorpion). Both are anti-predator defences.
📘 Read it in NCERT: Class 12 Biology, Ch 11 (practise this chapter) · Class 12 Biology, Ch 11 (practise this chapter)
Sources
- NCERT Class 12 · Biology, Chapter 11 “Some are poisonous and therefore avoided by the predators. The Monarch butterfly is highly distasteful to its predator (bird) because of a special chemical present in its body.”
- NCERT Class 12 · Biology, Chapter 11 “Some species of insects and frogs are cryptically-coloured (camouflaged) to avoid being detected easily by the predator. Some are poisonous and therefore avoided by the predators.”
- US CDC Yellow Book, Food Poisoning from Marine Toxins: pufferfish (fugu) poisoning ↗ “Pufferfish poisoning occurs after ingestion of fish containing tetrodotoxin, a potent neurotoxin. Potentially toxic fish are distributed widely worldwide and include pufferfish, porcupine fish, and ocean sunfish. The toxin is usually concentrated in the ovaries, liver, intestine, and skin of the fish.”
Question and answer: UPSC's official GS Paper I (2024, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·