PARIS: Dung beetles use light from the Milky Way to roll their balls of precious dung out of the way of competitors, scientists reported on Friday.

Even though they have just a tiny brain and weak eyes, the beetles use the progressive gradient of light in the skies, provided by the galaxy's mass of stars, to ensure they roll the balls in a straight line and do not circle back to rivals at the dung pile.

In an unusual experiment, biologists at South Africa's University of the Witwatersrand put dung beetles under a simulated night sky provided by the local planetarium.

The Milky Way provided the beetles with a "light compass," helping them to go in a straight line with their treasure, they found.

"The dung beetles don't care which direction they're going in -- they just need to get away from the bun fight at the poo pile," lead researcher Marcus Byrne said in a press release.

Some animals -- seals, some birds and humans themselves -- have been found to use the stars for navigation, but the dung beetle is the first animal that has been shown to use the galaxy itself.

Previously, the team found that dung beetles clambered on top of their dung balls, where they performed a little dance to look for the best light sources for orientation.

The Sun, the Moon and galactic light appear to be their favourites, rather than a man-made source. A celestial body is so far away that, from the beetle's perspective, it is immobile and thus provides a fixed reference point.

The new paper appears in the US journal Current Biology.