Most animals possess some kind of “signaling” communication system. Among
certain species of spiders there is a complex system for courtship. The male spider,
before he approaches his ladylove, goes through an elaborate series of gestures
to inform her that he is indeed a spider and a suitable mate, and not a
crumb or a fly to be eaten. These gestures are invariant. One never finds a creative
spider changing or adding to the courtship ritual of his species.