The amazing ability of the gecko to
cling to wet glass upside down, as well as a variety of less slippery and hazardous surfaces, without batting a non-existant
eyelid, has only recently been properly understood.
Far from having anything so inelegant as hooks (which wouldn't grab glass or metal anyway) on its feet, the humble gecko has developed a mechanism whose engineering ingenuity far surpasses anything we humans have so far come up with.
The bottom of the gecko's foot is covered in millions of microscopic, hair like structures which in turn each split into microscopically fine fibres at the ends. These fibres actually bond with whatever surface the gecko is trying to hang on to and so stop it falling. It is because of this that geckos rarely if ever slide - it is possible, just, to make a gecko fall off of a surface, but it simply cannot slide off without breaking the laws of physics.