Bubbles from the Naturalist Jerry's tank - by Jerry Ligon

January 2007: Much deeper than just a dive

An amazing study was recently completed and written in a scientific journal that indicates that two species of fish actually cooperate in their hunting efforts. Cooperative hunting has never been observed in fish before. The study was done in the Red Sea among groupers and moray eels.  What makes this study so interesting is that we have been relying on finding moray eels on our dives by watching for a specific group of fish that swim very close to the reef and in a predictive manner that we readily recognize and swim toward this group and can almost always find an eel moving into and out of crevices and under coral rubble.  What this Red Sea study shows to be different, thus far, is that the hunting groupers usually miss catching small fish near the reef who then dart into a nearby crevice where the grouper is unable to pursue.  The grouper then finds a nearby eel, usually resting under a coral head with just its head protruding.  The grouper wags its head back and forth in front of the eel and then, amazingly, the eel follows the grouper to where the small fish escaped.  The eel is ideally suited to go into small openings and create a panic in any small fish who try to dart out of the eels range, going out into the open water where the grouper is waiting.  Often the pay-back is for the eel who captures the escaping fish, and often it is the grouper who benefits.  Any way, someone gets food and the behavior is established for the benefit of each.

What we need to watch for here on Bari and on Bonaire is the initiation of the cooperation.  We have not been aware, until now, to try to watch for the initial reaction of the grouper and the eel.  We catch the cooperation after it has been started, and have never seen the beginning.  That is now uppermost in a lot of my students minds when diving-too try to establish if this behavior is more than just coincidental hunting here in Bonaire as it definitely is in on other reefs in the world.

Click here to view the original article about this study

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