Tree frogs' feet aren't nearly as powerful as those of the well-studied gecko, but their traction is good enough that they can grip the underside of a wet, slick leaf. Now, researchers have evidence that the tree frog's foot may be surprisingly sophisticated.
Unlike a gecko's toe, which uses dry, sticky hairs to clutch a surface (SN: 8/31/02, p. 133: Available to subscribers at Getting a Grip: How gecko toes stick), the pad on the bottom of a tree frog's toe is coated with a mucus film. This layer of fluid led scientists to think that the pads cling to a surface by wet adhesion—the force that makes a damp piece of paper stick to a window, for example.
But it turns out that wet adhesion is