How do tree frogs hang on? This is an excerpt from a post at Scientific American …
Biologist Jon Barnes of the University of Glasgow in Scotland, who led the research, used an atomic force microscope (AFM), which can provide images on the scale of billionths of a meter, to scan the feet of White’s tree frogs. To the naked eye, the frogs’ toe pads appear patterned with flat-topped, hexagonal cells surrounded by grooves filled with mucus. On closer inspection, however, Barnes discovered that the tops were not flat at all but rather were covered by tightly packed “nanopillars,” each with a small dimple in the end, which generate powerful friction against the surfaces they contact.
Although mucus can be a lubricant, for tree frogs the substance—only 1.5 times more viscous (resistant to flow) than plain water—serves as a “wet” adhesive. The reason: the nanopillars and larger structures on the toe pads come in direct contact with surfaces. As a result, the small amount of wet mucus between these protrusions provides adhesive forces … CONTINUED
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