Friday, January 25, 2013

Amazing dung beetles navigate by Milky Way star light

National Geographic   Moving in a straight line is crucial to dung beetles, which live in a rough-and-tumble world where competition for excrement is fierce. (Play “Dung Beetle Derby” on the National Geographic Kids website.)

Once the beetles sniff out a steaming pile, males painstakingly craft the dung into balls and roll them as far away from the chaotic mound as possible, often toting a female that they have also picked up. The pair bury the dung, which later becomes food for their babies. [...]

Scientists already knew that dung beetles can move in straight lines away from dung piles by detecting a symmetrical pattern of polarized light that appears around the sun. We can’t see this pattern, but insects can thanks to special photoreceptors in their eyes.

But less well-known was how beetles use visual cues at night, such as the moon and its much weaker polarized light pattern. So Warrant and colleagues went to a game farm in South Africa to observe the nocturnal African dung beetle Scarabaeus satyrus. (Read another Weird & Wild post on why dung beetles dance.) [...]

Dung beetle researcher Sean D. Whipple, of the Entomology Department at the University of Nebraska-Lincoln, said by email that the “awesome results …. provide strong evidence for orientation by starlight in dung beetles.”

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