Caterpillars' Whistle

CAT 2017 Slot 2 · VARC · Medium · Paragraph Summary

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The passage is followed by four summaries. Choose the option that best captures the author's position.

North American walnut sphinx moth caterpillars (Amorpha juglandis) look like easy meals for birds, but they have a trick up their sleeves - they produce whistles that sound like bird alarm calls, scaring potential predators away. At first, scientists suspected birds were simply startled by the loud noise. But a new study suggests a more sophisticated mechanism: the caterpillar's whistle appears to mimic a bird alarm call, sending avian predators scrambling for cover. When pecked by a bird, the caterpillars whistle by compressing their bodies like an accordion and forcing air out through specialized holes in their sides. The whistles are impressively loud - they have been measured at over 80 dB from 5 cm away from the caterpillar - considering they are made by a two-inch long insect.

  1. A.

    North American walnut sphinx moth caterpillars will whistle periodically to ward off predator birds - they have a specialized vocal tract that helps them whistle.

  2. B.

    North American walnut sphinx moth caterpillars can whistle very loudly; the loudness of their whistles is shocking as they are very small insects.

  3. C.

    The North American walnut sphinx moth caterpillars, in a case of acoustic deception, produce whistles that mimic bird alarm calls to defend themselves.

  4. D.

    North American walnut sphinx moth caterpillars, in a case of deception and camouflage, produce whistles that mimic bird alarm calls to defend themselves.

Answer

C

Explanation

Option C The paragraph explains how North American walnut sphinx moth caterpillars scare off bird predators: the caterpillar's whistle appears to mimic a bird alarm call, sending avian predators scrambling for cover. Option 1 talks of a 'specialized vocal tract' which is not mentioned in the paragraph. Option 2 is incorrect as explained in the paragraph; it is not the loudness of the noise but the fact that it mimics a bird alarm call that frightens away the birds. Option 4 mentions 'camouflage', which is not discussed in the paragraph.

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