In an article for the Outlook.com website BBC News Science Correspondent Jonathan Amos says scientists have shown how the insects will use the Milky Way to orient themselves as they roll their balls of muck along the ground.
“Humans, birds and seals are all known to navigate by the stars. But this could be the first example of an insect doing so,” he writes.
Amos describes a study by Marie Dacke of the Lund University in Sweden. An article on her research published recently in the journal Current Biology.
According to Assistant Professor Dacke, the dung beetles are not necessarily rolling with the Milky Way or 90 degrees to it. They can go at any angle to this band of light in the sky and apparently use it as a reference.
Dung Beetles like to run in straight lines. When they find a pile of droppings, they shape a small ball and start pushing it away to a safe distance where they can eat it, usually underground.
Getting a good bearing is important because unless the insect rolls on a direct course, it risks turning back towards the dung pile where another beetle will almost certainly try to steal its prized ball, Amos noted.
Dr. Dacke, a native of South Africa, had previously shown that dung beetles were able to keep a straight line by taking cues from the sun, the moon and even the pattern of polarized light formed around these light sources. But it was the insect’s capacity to maintain course even on clear moonless nights that intrigued her.
Amos says the researcher took the insects (Scarabaeus satyrus) into the Johannesburg planetarium where she could control the type of star fields a beetle might see overhead. Importantly, she put the beetles in a container with blackened walls to be sure the insects were not using information from landmarks on the horizon, which in the wild might be trees, for example.
The beetles performed well when confronted with a perfect starry sky but just as well when shown only the diffuse bar of light that is the plane of our Milky Way Galaxy. Dr. Dacke’s take on this is that it’s the bar more than the points of light that is important.
“Beetles have compound eyes. And it’s known that crabs, which also have compound eyes, can see a few of the brightest stars in the sky.
“Maybe the beetle can do this as well, but we don’t know that yet. It’s something we’re looking at,” she says.
“However, we show the beetles just the bright stars in the sky, they get lost. So it’s not just the bright stars the beetles are using to orient themselves.”
In the field, Dr. Dacke says she has seen beetles run into trouble when the Milky Way lies flat on the horizon at particular times of the year. And, she suspects, many other creatures might be similarly affected.
For centuries, scientists have maintained that distant stars are too far away to have any measurable impact on earth. But mounting evidence from the biological sciences suggests an unknown mechanism does in fact appear to be at work forming consequential connections between an omnipresent cosmos and organic life on the planet.
It’s an oddity but also a mystery that lends at least a modicum of support for claims astrologers have been making since the dawn of civilization. That is, one doesn’t actually need to see or tactilely feel the stars in order to be guided by them.