Imagine walking backward, upside down, with your hind legs pushing a ball of poo, and knowing exactly where to go. Dizzy? Meet the amazing dung beetle who does it all without losing a beat.
The dung beetle dance
The dung beetle is named that for a reason -- it lives on the undigested food found in the dung of animals. It fashions this piece of dung into a ball of sorts and then rolls it away. It usually looks for some hiding place underground where it can then eat the ball. It is the dance that they do when they roll the ball away that has fascinated researchers.
Dung beetles walk backward, with their hind legs up pushing the ball. Their head is down, and their front legs on the ground. (See the video below.) But every now and then they stop, they climb on their ball, do a little pirouetting dance and climb down again to roll the ball. What do they do when they dance on top of the ball, is the question.
The answer is likely they are looking to get their bearings. How else would you know where you are going, when you are walking upside down and backward?! But there is a complication here. Dung beetles live in wild places, where almost every direction looks the same. Deserts are flat and hot for miles around. Forests are full of trees and grass. How does the beetle know where to go? And how does it travel in a dead straight line, without getting confused?
Marie Dacke is a biologist at Lund University in Sweden. She works on dung beetles and has shown in the past that they get their bearings from the sun. Dung beetles have compound eyes, they can see polarized light – this is the direction that light vibrates in. So when the dung beetle climbs on its ball and looks for the sun or the light, it knows where the light is coming from, and that helps it not double back on the way it came.
And now, The Milky Way
But what does it do at night? Studies have shown that just stars do not work. But show them the band of the Milky Way, and voila! They know where to go again. Humans and seals have been known to use the stars for navigation. But this dung beetle finding might be the first finding in the insect world. There may be others that use it too, scientists will have to keep looking.