Question

"Some species of insects and frogs have evolved with various specific features that help them from being detected."

1. Justify the statement giving reasons.
2. Mention any two such features.

Answer 1

(a) Prey species have evolved various defences to lessen the impact of predation. 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 predators.

(b) (i) The Monarch butterfly is highly distasteful to its predator (bird) because of a special chemical present in its body. Interestingly, the butterfly acquires this chemical during its caterpillar stage by feeding on a poisonous weed.

(b) (ii) Weed Calotropis growing in abandoned fields. The plant produces highly poisonous cardiac glycosides and that is why you never see any cattle or goats browsing on this plant. A wide variety of chemical substances that we extract from plants on a commercial scale (nicotine, caffeine, quinine, strychnine, opium, etc.,) are produced by them actually as defences against grazers and browsers.