Extremely rare and intelligent animal communication: Eel and grouper hunt together

Nassau Groupers are plentiful in the Caribbean and they are one of the biggest and most successful hunters on the reef. Highly intelligent, agile and powerful, they seek out and capture their prey by inhaling rapidly, sucking the smaller fish into their mouth. But smaller fish know that their best chance to avoid being eaten is to seek shelter among the crevices in the coral and sponges on the reef. Groupers know they can't fit their large heads into small holes, so they have learned to enlist the help of a creature who can. The Moray Eel is a long, slender fish that is also a top predator. It hunts mainly at night when its poor vision is less of a disadvantage. It has a keen sense of smell and a body that is designed for stealth. It glides along the coral, slithering in and out of hiding places with ease. Any fish that it encounters will have only a brief chance for escape by fleeing out into the open before it is grabbed by the eel's powerful jaws. Both of these creatures are formidable on their own, but they have learned to team up for a greatly improved hunting technique. Cooperation between two species is rare, and communication between different species is even more rare. There are many mutually beneficial relationships in the wild, but only a few examples of when it is intentional and when it is based on an understanding and communication. The grouper begins this process by finding an eel and facing it head on while it shakes its head rapidly and performs an obvious movement or "dance". The eel has long ago learned what this means and it will venture from its lair in the daytime to join the grouper. The grouper understands that it has superior eyesight and will signal the eel where the food is hiding. It uses a similar, but much slower head shaking, along with posture and an intent stare at the location where the eel needs to go. The eel will enter the crevice after the prey, which is now forced to face the eel or to venture out in the open and take its chances with the hungry grouper. The grouper may also simply follow the eel and remain ready to ambush unwary prey. This technique is at least five times as effective as either of them hunting on their own. One of the most interesting parts of this arrangement is that it is not complicated by competition for food. Both the eel and the grouper swallow their food whole, so one of them quickly gets the meal and there are no scraps left to fight for. It works out roughly equally for both so there is enough positive reward in the method to make it worth repeating. This is another demonstration of the fact that we are only starting to learn how complicated the animal kingdom really is and how intelligent animals can be. Groupers will also use this technique to signal scuba divers with spears to the fact that a lion fish is hiding in the coral. They can understand which divers are hunting and even which species they need to find. Incredibly, Nassau Groupers can even recognize a particular scuba diver who has fed them on past dives and they will greet and follow people they know.