A Compass Above the Dunes

Written by Studio AM.

A dung beetle that has shaped a ball of food needs to leave a crowded pile quickly. Other beetles may steal the ball, so wandering in circles is costly. Some ball-rolling dung beetles climb onto their prize, turn in place, and then push it away along a fairly straight route. Their useful compass is overhead.

By day, the Sun can provide a strong direction cue. Even when the Sun is partly hidden, patterns of polarized light across the sky can help some insects maintain a bearing. At night, certain dung beetles can use the broad glow of the Milky Way. This does not mean they read individual constellations as a person might. Instead, the uneven band of light gives them a large-scale orientation cue.

Researchers have tested these abilities by changing what beetles can see. In controlled arenas, small caps can block a beetle’s view upward, while projected skies can offer selected celestial patterns. Routes become less direct when useful sky cues disappear. Such experiments do not tell us what the journey feels like to a beetle. They do show that a small traveler can extract direction from light spread across an immense sky.

Questions

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  1. Question 1 of 4

    What is the passage mainly about?

  2. Question 2 of 4

    Why is a fairly straight route valuable to a ball-rolling beetle?

  3. Question 3 of 4

    In this passage, what is a “bearing”?

  4. Question 4 of 4

    What can researchers use to block a beetle’s view upward?

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