To study how ants get around, scientists have built the insects a pint-size treadmill. The treadmill is made up of a Styrofoam ball cushioned by a jet of air so it can roll freely as an ant walks on its surface. Sensors track the ball’s rotation to measure the ant’s speed and direction. It’s the first device sensitive enough to track the tiny insects’ movement and allow the animals to move just as they would in the wild.

“It’s a joy to observe the ants running so naturally,” says Hansjüergen Dahmen, a physicist at the University of Tübingen in Germany who designed the treadmill.