Data from: Frog tongue acts as muscle powered adhesive tape

Frogs are well known to capture fast moving prey by flicking their sticky tongues out of the mouth. This tongue projection behavior happens extremely fast which makes frog tongues a biological high-speed adhesive system. The processes at the interface between tongue and prey, and thus the mechanism of adhesion, however, are completely unknown. Here, we captured the contact mechanics of frog tongues by filming tongue adhesion at 2,000 frames/s through an illuminated glass. We found that the tongue rolls over the target during attachment. However, during the pulling phase, the tongue retractor muscle acts perpendicular to the target surface and thus prevents peeling during tongue retraction. When the tongue detaches, mucus fibrils form between the tongue and the target. Fibrils commonly occur in pressure sensitive adhesives and thus frog tongues might be a biological analogue to these engineered materials. The fibrils in frog tongues are related to the presence of microscopic papillae on the surface. Together with a layer of nano-scale fibers underneath the tongue epithelium, these surface papillae will make the tongue adaptable to asperities. For the first time, we are able to integrate anatomy and function to explain the processes during adhesion in frog tongues.