UPSC Prelims 2024 Q29: Environment & Ecology – Ecosystems & Ecology Concepts

UPSC Prelims 2024, General Studies Paper I · Environment & Ecology

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

Answer: (c) All three

Explanation

Poisonous species exist in all three groups

Group	Poisonous example	How it works
Butterflies	Monarch butterfly; Common Crow and Plain Tiger in India	Caterpillars eat milkweed, storing toxic cardiac glycosides
Fish	Pufferfish, stonefish, lionfish	Pufferfish carry tetrodotoxin; stonefish have venomous spines
Frogs	Poison dart frogs (South America)	Skin secretes batrachotoxin, among the strongest natural poisons

Poisonous vs venomous:

Term	Meaning	Example
Poisonous	Harmful if eaten or touched	Pufferfish, monarch, dart frog
Venomous	Injects toxin by bite or sting	Snakes, scorpions, stonefish

Bright warning colours (aposematism) often advertise this poison to predators.

Answer: (c) All three.

(a) Incorrect. All three groups have poisonous members, not just one.
(b) Incorrect. Butterflies, fish and frogs each include toxic species.
(c) CORRECT. Monarch butterflies, pufferfish and poison dart frogs show that all three groups have poisonous species.
(d) Incorrect. Many well-known species in all three groups are toxic.

Poisonous butterflies (monarch), fish (pufferfish) and frogs (poison dart) all exist; bright colours warn predators.

Butterflies, fish and frogs all have poisonous species.

Thinking butterflies are always harmless; many store plant toxins from their caterpillar food.
Mixing up poisonous (eaten or touched) with venomous (injected).
Forgetting that pufferfish (fugu) poisoning can kill humans who eat it.

Bright, bold colours in nature often mean 'don't eat me'. This warning colouring is called aposematism.

NCERT Class XII — Biology, Ch 13 (Organisms and Populations — Predation and defence)
Encyclopaedia Britannica — poison dart frog