Air Date: Week of July 11, 2003

Living on Earth’s Cynthia Graber reports on a new study that shows African dung beetles are navigating by the polarized moonlight.

Transcript

CURWOOD: Coming up: rethinking how to save nature. First, this note on emerging science from Cynthia Graber.

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GRABER: It’s known that some animals use patterns of sunlight to find their way around. But scientists didn’t know of any animals that used the moonlight— a million times dimmer than the daytime sun. Apparently, though, it’s not too dim for one African dung beetle. Beginning at sunset, the beetle starts its search for fresh piles of dung. Once it finds some, it has to get the dung away quickly to prevent other dung beetles from snatching its food. Scurrying in a straight line provides the quickest path to a secure location. Beetles plot this straight line by using polarized sunlight. When light waves from the sun strike particles in the atmosphere, the waves polarize, or line up in straight lines. But dung beetles continue to forage after darkness falls. Scientists wondered— could the animals be using moonlight in the same way?

So researchers monitored the insects at night. They observed that when the moon lights the sky, the beetles rush straight away. Without the moon, the beetles weave a wavy path. But was it the moon itself, or the light emanating from it that was guiding them? So scientists used filters to change the direction of polarized moonlight. When the polarization changed, the beetles changed direction as well. Scientists now suspect many other animals may use polarized moonlight to guide them.

That’s this week’s note on emerging science – I’m Cynthia Graber.

CURWOOD: And you're listening to Living on Earth.

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