| | Geckos' toes seem to be "double jointed", but this is a misnomer. Their toes actually bend in the opposite direction from our fingers and toes. This allows them to overcome the van der Waals force by peeling their toes off surfaces from the tips inward. In essence, this peeling action alters the angle of incidence between millions of individual setae and the surface, reducing the van der Waals force. Geckos' toes operate well below their full attractive capabilities for most of the time. This is because there is a great margin for error depending upon the roughness of the surface, and therefore the number of setae in contact with that surface. If a typical mature 70g gecko had every one of its setae in contact with a surface, it would be capable of holding aloft a weight of 133 kg: each spatula can exert an adhesive force of 10 nN.
The family Gekkonidae is divided into five subfamilies, containing numerous genera of gecko species. Many geckos are kept as pets and will eat various kinds of insects and sometimes fruit. | |
