The Toothy Tag-Team

Sometimes it seems that the prey have it all their own way. From clever camouflage to flashing speed to seeking safety in numbers, the little guys have such a bewildering array of sneaky survival tactics to choose from that it’s a wonder any of them end up getting eaten at all. So when a hungry predator is at its wit’s end and having no luck in securing a meal, it sometimes pays to partner up with an equally deadly accomplice when it’s time to go hunting.

That’s what groupers do when they’ve been unsuccessfully trying to feed. The large fish’s great bursts of speed make it deadly in the open water, but sometimes crafty prey can avoid it by hiding in the narrow nooks and crannies of a reef.  When that happens, the stubborn grouper doesn’t turn tail and head for home – instead, it signals to any passing giant moray eels that they should team up to hunt together.

By using a specific, vigorous “shimmy”, the grouper summons the giant moray for a tag-team effort, taking advantage of the eel’s sinuous body to get into the tight spaces of the reef and flush out the prey together. By cooperating in this way, the hungry duo leaves their hapless prey with literally nowhere to hide, and both benefit far more than when hunting alone.

Scientists have even observed the grouper using a second, rarer signal – standing on its head directly above any hidden prey that it’s failed to catch, thus pinpointing the location of the tasty meal to its toothy partner in crime. This kind of “referential” gesture is similar to a human pointing to an object but the only animals that seem to use them are relatively intelligent ones such as apes, dogs and dolphins. While that might indicate that the grouper is more clever than we give it credit for, scientists are wary about labelling it an aquatic genius just yet, theorising instead that the behaviour may simply be evolved rather than intentional.