I just witnessed a small jumping spider jump on some kind of louse or bed bug on the ceiling. How does it do that without falling? I have yet to find a high-speed-camera video of a jumping spider jumping on a ceiling.
My hypothesis is that the spider would spit silk and anchor it on the ceiling, then jump, and allow itself to be swung by the silk onto the prey. But I don't have a high speed camera to prove that.
EDIT: I now have some evidence that supports my hypothesis: I just saw a jumping spider attempt to jump on a prey and failing to land properly. It didn't fall directly to the floor. Instead, it dangled from its own silk, at about 2 cm from the ceiling, then climbed right back up the thread of silk, onto the ceiling.