Cockroaches are famed for the way they can skitter away and disappear before you get a chance to whack them.
It's a trick that could be useful for robots, particularly in the military, and now scientists have worked out how it's done.
The University of California, Berkeley, biologists and robotics experts say that one of its most effective techniques is to flip under a ledge.
It runs at full speed toward the ledge, dives off, then grabs the edge with its claws – sometimes using only one leg – and swings 180 degrees to land firmly underneath, upside down.
The team first noticed the behavior while studying how they use their antennae to sense and cross gaps.
"As we made the gap wider, they would end up on the underside of the ramp," says graduate student Jean-Michel Mongeau. "To the naked eye, it wasn’t clear what was happening, but when we filmed them with a high-speed camera and slowed it down, we were amazed to see that it was the cockroach’s hind legs grabbing the surface that allowed it to swing around under the ledge."
Surprisingly, the researchers discovered a similar behavior in lizards and geckoes.
"This behavior is probably pretty widespread, because it is an effective way to quickly move out of sight for small animals," says professor of integrative biology Robert Full.
The team was able to recreate the behavior in a six-legged robot by adding Velcro strips to the rear legs of a small, cockroach-inspired, six-legged robot called DASH, or Dynamic Autonomous Sprawled Hexapod.
“Today, some robots are good at running, some at climbing, but very few are good at both or transitioning from one behavior to the other," says Full.
"That’s really the challenge now in robotics, to produce robots that can transition on complex surfaces and get into dangerous areas that first responders can’t get into."