Chimps have been tested for this quality using rope-pull experiments: A plank holding fruit is placed parallel to but out of reach from a cage, with a rope attached to either end. Chimps are evaluated based on their ability to realize that they need a co-conspirator to tug the fruit in, and how successfully they can work together.
The coral trout is known to work with other species when it hunts for food, but researchers couldn't test the fish's coordination skills by dumping ropes and fruit into the water. Instead, they presented the fish with food that was either easy to get, or hidden within a hard-to-reach crevice (as it often would be in a reef).
Researchers used fake moray eels, known to be frequent collaborators of the trout. When the fish used their usual tricks to get help from an eel -- shaking their heads and even doing headstands to point the predator in the direction of hidden prey -- these fake decoys would either swim toward it, scaring the food out into the open, or swim in the opposite direction.
On day one of the experiment, the fish sought out help 83 percent of the time that they should have, which is comparable to rates seen in chimps. But on day two, the fish surpassed the primates: They were over three times more likely to choose the effective hunting partner over the one that swam in the wrong direction. This, the researchers reported, suggests that the fish are actually better at learning who to buddy up with than are chimps.
What's cool here is that the trout are showing more complex behavior than the chimps (albeit in one very specific circumstance) even though their brains are decidedly less complex. "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," lead author Alexander Vail, a Gates Scholar at the University of Cambridge, said in a statement.
The skill of conscious collaboration may be more common than we thought, and it's possible that it's a survival trait that's evolved time and time again in different species.