Scientists believe they have solved the mystery of why beetles spend so much time “dancing” on top of balls of freshly rolled animal dung.
A scientific article published on Wednesday by South African and Swedish researchers suggests that the dancing dung beetles are in fact taking detailed compass readings from the sun and the heavens, to enable them to roll their dung swiftly out of reach of rival beetles intent on stealing the pungent balls.
The research paper, titled “The Dung Beetle Dance”, was published online in the Public Library of Science journal PLoS One, following a series of recent experiments at Stonehenge farm in Limpopo.
The researchers, including Prof Marcus Byrne of the Wits University school of animal, plant and environmental sciences, says that dung-eating beetles fashion balls of fresh animal faeces and then roll them away to underground pantries.
While rolling, the beetles move the dung pile in a straight line, “a remarkable feat given that they do this while facing backwards, with their heads pointing towards the ground”.
Byrne and co-author Emily Baird of Lund University in Sweden say that it is crucial for the beetles to roll the ball backwards in a straight line – a strategy which ensures that the ball is rolled directly away from other marauding beetles, which prefer to capitalise on the work of others by poaching ready-rolled balls.
“Interestingly, just before rolling a ball away from the dung pile, beetles often perform a characteristic ‘dance’. During this dance, the beetles climb on top of the ball and rotate about their vertical axis while performing a series of brief pauses, before climbing down to roll,” Byrne and Baird say.
Beetles often repeat this performance if their balls roll off course or bump into an obstacle.
Byrne and his co-researchers conclude that the mysterious dance serves the purpose of gathering visual clues from the sun, moon, the Earth’s magnetic field or the nearest tall tree, much like taking a compass bearing before a long journey.
To test the theory, the researchers conducted a series of experiments with 31 beetles. The beetles were painted with tiny identification markings and then filmed with a video camera while they tackled a series of obstacle courses and experiments. The experiments included digging trenches, blocking the pathways, shining mirrors and blacking out the horizon to observe what the dung beetles did when their balls went awry.
Sure enough, most beetles climbed up and “danced”.
The researchers concluded that the beetles were simply taking fresh compass readings after going off course.
“The most effective way to correct for such errors would be for the beetle to scan the environment… until the compass reading once more matches the reading that the beetle stored when it first started rolling.” - The Mercury
* See www.plos.org/media/press/2012/pone-07-01-baird.pdf.
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