Dung beetles navigate using the gentle glow of the Milky Way over Africa—the first known case of an animal using this feature to find its way rather than with the stars.
A Swedish-South African research team discovered that the insects push their balls in straight lines on clear nights, but cannot do this when it is cloudy.
When tested inside a planetarium, the beetles moved around just as well under a starlit sky as under one with only the whitish band of the Milky Way.
“Even on clear, moonless nights, many dung beetles still manage to orientate along straight paths,” said study co-author Marie Dacke at Sweden’s Lund University in a press release.
“This led us to suspect that the beetles exploit the starry sky for orientation—a feat that had, to our knowledge, never before been demonstrated in an insect.”
The night sky contains many stars, but most are probably not bright enough to be detected by the beetles’ little compound eyes.
These results suggest other insects might also use the stars to orient themselves at night.
“Dung beetles are known to use celestial compass cues such as the sun, the moon, and the pattern of polarized light formed around these light sources to roll their balls of dung along straight paths,” Dacke said.
“Celestial compass cues dominate straight-line orientation in dung beetles so strongly that, to our knowledge, this is the only animal with a visual compass system that ignores the extra orientation precision that landmarks can offer.”
The study was published online in Current Biology on Jan. 24.
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