Science-----Why the lizard can hold on the wall

Like most kinds of geckos (lizards) have ridges on their toes. Each ridge is covered with tiny, tiny hairs--lots of them. We are talking maybe a million hairs on each foot. The hairs help the feet stick to surfaces by making a special kind of energy. This energy works a lot like static electricity called Van Der Waal's force. Lizards do not have suckers on their foot as in Octopus.

The toes of the gecko have attracted a lot of attention, as they adhere to a wide variety of surfaces, without the use of liquids or surface tension. Recent studies of the spatula tipped setae on gecko footpads demonstrates that the attractive forces that hold geckos to surfaces are van der Waals interactions between the finely divided setae (almost 500,000 Setae on each foot, and each of these tipped with between 100 and 1,000 spatulae) and the surfaces themselves.[1] These kinds of interactions involve no fluids; in theory, a boot made of synthetic setae would adhere as easily to the surface of the International Space Station as it would to a living room wall. Geckos' toes are extremely double jointed, allowing 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. Amazingly, Geckos' toes operate well below their full attractive capabilities for most of the time. This is because there is a huge margin for error depending upon the roughness of the surface, and therefore the number of spatulae in contact with that surface. If a gecko had every one of its spatulae in contact with a surface, it would be capable of holding aloft a 120 kg man[citation needed].

具有趾墊，趾墊上的小鉤可協助附於不規則的表面上。