I’m not going to even to try to summarize this; just go over to Ed Yong’s blog and read about how groupers and moray eels collaborate to hunt down prey. Using gestures to communicate. There are videos.
The giant moray eel can grow to three metres in length and bites its prey with two sets of jaws—the obvious ones and a second set in its throat that can be launched forward like Hollywood’s Alien. It’s not a creature to be trifled with. But the coral grouper not only seeks out giant morays, but actively rouses them by vigorously shaking its body. The move is a call to arms that tells the moray to join the grouper in a hunt.
The two fish cooperate to flush out their prey. The grouper’s bursts of speed make it deadly in open water, while the moray’s sinuous body can flush out prey in cracks and crevices. When they hunt at the same time, prey fish have nowhere to flee.