Researchers have discovered that dung beetles can navigate in straight lines using nothing more than the soft glow from our home galaxy.
That's kind of awesome, but it's worth asking, at this point, just why the heck dung beetles have any need to navigate. They find poo. They make poo into balls. They roll the balls off somewhere, and then lay their eggs in them and bury them. Seems straightforward, right? But that's the amazing thing: it's absolutely straightforward. Once a dung beetle has created a ball of poo, it heads away from the pile as fast as it can go in a dead nuts straight line. It goes around whatever obstacles are in its way, but continues going straight, which is quite remarkable considering that it's often traveling backwards and partially upside-down.
So why do they care about straight lines? The answer seems to be that the beetles with poo balls are just trying to get away from all the other beetles in 'round the pile as fast as they possibly can.
Making a ball of excrement that's larger than you are is a lot of work, and once you put one together, other beetles will try and steal it. The quickest and most efficient route of escape from a poo pile is a straight line, so that's what the beetles do. They're quite clever about it, too, able to sense when they've veered off course and using light from the sun to reorient themselves:
That's all well and good during the day, when the sun's out, but what happens at night?
Research (performed by outfitting the beetles with little hats to block their view) has shown that the bugs' compound eyes are sensitive enough to detect light from the Moon, the stars, and most impressively, the Milky Way itself. Apparenty, all a dung beetle needs is one fixed pattern in the sky that it can recognize, and then it's able to use that pattern to make sure that it's always moving in a straight line. Along with its giant ball of poo. Thank you, science!