Context: The Plain Tiger butterfly has the ability to thrive even in increasingly concretised cities like Delhi.
- That’s because their choice of larval host plants (food for caterpillars) — milkweed.
- These plants contain toxins — cardenolides in the case of milkweed — that make the caterpillar as well the butterfly unpalatable.
- Their toxic nature, due to their diet, makes them one of the commonest butterflies in India.
- This plant also aids in the survival of the Painted Grasshopper and other insects.
- In fact, tribes across the world use the poison in the plant on arrow-heads to aid in hunting.
- The vibrant colouration of the Plain Tiger sends a warning signal to its predators — birds, lizards — that they could be toxic. This defence mechanism is known as aposematism.
- The colouration is mimicked by other species like the female Danaid Eggfly butterfly that often move with Plain Tiger butterflies to avoid being eaten alive. This is another of nature’s defence mechanisms, called Batesian Mimicry. Yet another survival mechanism is the haphazard zig-zag flight that the butterfly has to avoid capture.
Some other defence mechanisms in nature:
- Cryptic coloration (camouflage) - coloring scheme that allows an animal to blend into colors in its environment.
- Deceptive markings - patterns that cause an animal to appear larger or more dangerous than it really is.
- Aposematic (warning) coloration - warning coloration exhibited by animals that possess a chemical or structural defense.