Dung Beetles Navigate Using Mental Snapshots of the Sky
We may giggle about the diet of dung beetles, but these bugs have an awful lot to teach us about animal minds. Researchers have found that dung beetles use mental snapshots of the sky to find their way. The report was published in the journal Current Biology.
These are the same researchers from Lund University who previously outfitted their dung beetle subjects with tiny vision-blocking hats to determine if the bugs were navigating by sight (they were). Once the scientists realized that the beetles were looking at the sky to get their bearings, they wanted to know how it worked.
The research team, led by Lund University researcher Basil el Jundi, suspected that the navigation process might be associated with the beetle’s habit of climbing atop its dung ball and turning in a circle, a process the researchers call dancing.
The scientists brought dung beetles (in this case, Scarabaeus lamarcki) into an arena with an artificial sky, which allowed them to manipulate the sources and amount of light the beetles could see. They ran three separate experiments to tests the bugs’ responses to light polarization patterns, gradients of colored light, and different intensities of light—all factors that influence the navigation of other traveling insects like bees and ants.
In the end, it was all about the dance. Beetles were able to roll their dung balls away in a straight line if they had the opportunity to rotate in a circle while watching the sky. During that time, the researchers say, the insects were taking mental snapshots of the positions of the artificial stars and planets, which they then translated into maps for their movement on Earth. Pretty sophisticated stuff.
"Other animals and insects also use the position of celestial bodies to navigate,” el Jundi said in a press statement, “but the dung beetles are unique—they are the only ones to take a snapshot where they gather information about how various celestial bodies, such as the Sun, Moon, and stars, are positioned.”
Specialized map-making is not unique to dung beetles. Little fish called frillfin gobies spend much of their lives in tidal pools. When the water level in their pool diminishes, the fish are able to jump into another pool, even though they can’t see where they’re going. Scientists in the 1950s realized that the fish make mental maps of the entire tidepool region as the ocean carries them up and into the pools. The gobies memorize the overhead map, then translate it into ground-level topography to help them decide which way to jump.