Coral trout and moray eel team up to catch prey, a new study by researchers at the University of Cambridge suggests. These two organisms, each from different species, can work together to achieve a shared goal: eating smaller fish.

Coral trout track smaller fish to eat. Sometimes, those fish swim into tiny crevices of coral reefs, where the trout can't reach them. When this happens, researchers found that coral trout give a sign to nearby moray eel that there is prey in the reef. The eel then go after the prey, and either scare them out of the reef and into the waiting arms (or fins) of the trout, or the eel catch and eat the prey.

The coral trout uses body language to tell the eel that there is prey in the reef, sometimes by shaking its head in the right direction. This symbiotic relationship, facilitated by the coral trout, shows that the species has an astonishing ability to manipulate a situation to achieve a goal. The fish are surprising experts at collaboration. A new study, published September 8 in the journal Current Biology, shows that coral trout's ability to size up potential collaborators matches or even exceeds that of chimpanzees.

A video released by the researchers shows some of what the experiment looked like. The experimenters collected wild coral trout and placed them in an artificial environment that mirrored their natural habitat, with an artificial moray eel. The experiment was designed to mirror a 2006 experiment in which chimpanzees were placed in a situation with food beyond their reach, where two chimpanzees would have to work together to pull a rope until they got the food.

The coral trout were placed in a situation where prey was located beyond their reach in the crevices of a reef. The fish needed to use the help of a synthetic "eel" to get the prey out of the reef. The fish were given one day to observe how successful each collaborator was. By day two, the researchers found that the coral trout successfully chose the better collaborator in 83 percent of the cases. This surpassed the ability of chimpanzees in the earlier study.

"This study strengthens the case that a relatively small brain - compared to warm-blooded species - does not stop at least some fish species from possessing cognitive abilities that compare to or even surpass those of apes," said Alexander Vail, the lead author of the study.