The foot of a common house gecko

     While it can be found throughout Mesoamerica, the common house gecko (Hemidactylus frenatus) is a actually a native of southeast Asia.  The story is that the population started from escaped pets.  Here in El Salvador, the house geckos do exceptionally well in urban areas & suburban parks (where homes & 24hr street lights are abundant) and they seldom venture deep into the few remaining large natural areas.  How a gecko's feet work is simply spectacular: β-keratin spatula-shaped bristles arranged in plate-like footpads (white above) allow attractive intermolecular van-der-Waals forces (i.e. non-covalent bonds!) to form between the footpad & a given surface.  Here's a great paper by Herrera et al. 2005.