Predator fish team up

In the first known example of interspecies-cooperative hunting in fish, the moray eel and the grouper have learned (if "learned" is the right word) to work together in the Red Sea. When a stoutly built grouper, a daytime hunter, chases prey into a crevice too small for pursuit, the grouper looks for the nearest moray. The moray, which is normally resting in a crevice of its own waiting for nightfall, is lured out by the grouper's act of shaking its head. The grouper then leaders the moray to the prey. The two predators do not apparently share the meal - sometimes the grouper gets it, sometimes the moray does, but for the grouper, this at least provides a chance at prey that would otherwise escape. The complexity of this behavior (How does the grouper "know" the moray will cooperate? Why does the moray respond to the head shaking?) is puzzling and downright amazing.