Rachel Nuwer in Scientific American:
Spider legs seem to have minds of their own. According to findings published in the Journal of the Royal Society Interface, each leg functions as a semi-independent “computer,” with sensors that read the immediate environment and trigger movements accordingly. This autonomy helps the arachnids quickly spin perfect webs with minimal brain use. The study authors simulated surprisingly simple rules to govern this complex behavior—which could eventually be applied to robotics.
More here.