<p>(A): The spider is in the middle of the web waiting for prey to hit the web; it will sense the vibration. (B): The spider senses the fly hitting the web and begins to withdraw its legs and move in the direction of the vibration. The spider is showing directional orientation toward the fly. (C): The spider has left the center of the web and is moving along the primary tension member of the web in the direction of the fly. (D): The spider comes in contact with the fly, seizes the fly, wraps it or eats it. (E): When the fly is consumed the spider starts the return to the center of the web. Again, the orientation of the spider is away from the original disturbance and toward the center of the web. (F): The spider, back at the center of the web, has re-extended its legs to the primary tension members of the web waiting until for another disturbance, or a new meal. The direction of the action is driven by a vibration disturbance that is sensed in the legs of the spider. Microglia appear to use their processes as spider legs and move to the injured site.</p
