Well, something with 6 legs will move by creating a tripod with three of them to balance on, then move the other three forward. So in one step, the front left, back left, and middle right would be on the ground, pushing it forward, and the middle left, front right, and back right would be in the air moving ahead of the spider. Then they would alternate, the ones that just moved forward would take the weight, and the other three would rise up and move forward.
