When a caterpillar starts moving in that slow-motion, lurching way, its insides don't simply follow or slosh around like jello — its insides actually slide forward before the body does, according to a new study cited by Scientific American. This bizarre, never-before-seen "wave" movement may inspire some new designs in a surprising field: soft-bodied robots.

The research team at Tufts University made the discovery entirely by accident, observing the movement of caterpillars with X-ray technology for a neurosensory experiment. They expected to see fluid moving around in the caterpillar's body, but were shocked when the organs in its mid-body segments swung forward before its legs moved.

"One way to think about it is to imagine you're crawling on your hands and feet," lead author Michael Simon told Discovery News.

"Normally, as you move forward, all of your internal tissues move forward with you. It makes sense, as it's all packed into your rib cage. But imagine if, instead, as you began to bring your back leg forward, your liver suddenly began to slide upward toward your neck."

Simon explains that as a caterpillar begins to move in a forward wave-like motion, its gut actually changes shape and moves within the body, independent of the muscular contractions in the body wall that propel the creature forward.

Because this strange way of moving seems to improve the insect's balance, control, and grip, according to Discovery News, application of this gut-first motion could be applied to soft-bodied robots that carry fragile internal cargo, such as search-and-rescue robots equipped with surveillance equipment.

Caterpillars' guts move before their bodies
Surprise finding could help inspire new designs in the field of soft-bodied robots.