Humble dung beetle found to be a celestial navigator

Wit University/Marcus Byrne
Dung beetle wears a small cap that researchers used to block
out starlight.

The next time that expats are outside finding their direction by the stars, they might not be alone.

Researchers at a South African university report that dung beetles also use the Milky Way to ensure they keep rolling their balls in a straight line and don’t circle back to competitors at the dung pile.

Costa Rica has an incredible 175 species of dung beetles, according to a research report by the Instituto Nacional de Biodiversidad.

The beetles, Scarabeidae, are the little insects that roll dung into round balls. They also are known as scarab beetles, and some species were sacred in ancient Egypt.

Scientists from South Africa and Sweden have published findings showing the link between dung beetles and the spray of stars which comprises our galaxy, according to Wit University in Johannesburg, South Africa.

“Although their eyes are too weak to distinguish individual constellations, dung beetles use the gradient of light to dark provided by the Milky Way to ensure they keep rolling their balls in a straight line and don’t circle back to competitors at the dung pile,” said the university in a description of the research.

Marcus Byrne of the university and his team previously proved that dung beetles use the sun, the moon and polarized light for orientation, the Wit summary noted, adding that in their experiments, they gave the beetles caps which blocked light from reaching their eyes. The team also discovered that the beetles climb on top of their dung balls to perform an orientation dance during which they locate light sources to use for orientation, it said.

Further experiments, conducted under the simulated night sky of the Wits Planetarium, have shown that the beetles also use the band of stars that make up the Milky Way.

The scientists suspect the beetles have a hierarchy of preference when it comes to available light sources, according to the university. So if the moon and the Milky Way are visible at the same time, the beetles probably use one rather than the other, it noted.

A few other animals have been proven to use stars for orientation, but the dung beetle is the first animal proven to use the galaxy, the university said.

The Instituto Nacional de Biodiversidad has a collection of a number of dung beetle specimens. The insects are monitored closely because they are indications of biodiversity and changes brought about by climate.

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