This video from the USA says about itself:
1 September 2016
Biologists studying caterpillars have reported a unique “two-body” system of locomotion that has not previously been reported in any animal. The gut of the crawling caterpillar moves forward independently and in advance of the surrounding body wall and legs, not with them. This novel system may contribute to the caterpillars‘ extraordinary freedom of movement and provide insight for the design of soft-bodied robots. Anyone who has ever observed caterpillars knows that they crawl from back to front in waves. But advanced imaging reveals a surprising picture of what goes on inside.