In a tour-de-force performance a spider defies gravity and physics in a succession of seemingly impossible feats of strength and balance as he traverses a wire that appears to give him no support. At one point he hangs at a 45-degree angle over the ground, some 15 feet below, and he tops that with an upside-down unicycle act. And the wire is in almost-constant motion up and down, adding to the degree of difficulty.