What helps caterpillars to crawl on oak leaves?

Caterpillars. They are so small and unremarkable. It is far from always possible to notice it on a sheet that is right in front of your eyes. All because of its color. Often, caterpillars can be seen in the warm season, in the leaves of linden, maple, willow rolled into tubes, on bushes and grasses. But, what helps the caterpillars to move so easily over smooth leaves and trees without falling to the ground? The answer is simple. At the ends of their legs there are small claws in the form of hooks, with which it clings to the slightest roughness and irregularities.