Unexpected movements within the abdomens of caterpillars are giving scientists new ideas in locomotion engineering for soft-material robots. Using real-time X-Ray imaging, researchers at Virginia Tech and Tufts found that the caterpillar's gut slid forward in advance of the surrounding tissues. These unexpected interactions between internal and external structures offer new efficiencies for motion which could lead to improvements in designs for future robots needing to crawl in certain environments.