These are scary! Not big but fast as heck and can run up any surface. Yikes.

"Many hunting spiders possess dense hair tufts called scopulae under the claws of their tarsi (feet). These scopulae allow many spiders to walk on smooth vertical surfaces, across ceilings and even window panes. Each individual scopula hair splits into thousands of tiny extensions known as end feet. These end feet increase the number of contact points of the tarsi with the surface, creating great adhesion. This is similar to the adhesion forces at work in vertebrates such as skinks and geckos, which can also walk on ceilings with ease. The scopulae can be erected or laid flat by hydraulic pressure through changes in the pressure of the hemolymph (blood supply)." from amonline.net.au/spiders