Clever Coral Trout Get Choosy with Hunting Partners

Don't play games with clever coral trout, because they just might outsmart you. New research shows that like chimpanzees, coral trout can get choosy with their hunting partners to optimize their chances of nabbing some food.

The findings, described in the journal Current Biology, show that fish may have remarkable cognitive abilities that are usually characteristic of warm-blooded, bigger-brained species, like humans and other primates.

Coral trout in particular are remarkable in the fact that they understand how to cooperate with other species to improve their chances of a meal. Although this trout, of the genus Plectropomus, can easily hunt down smaller fish as it swims over coral reefs, where it struggles is within the tiny crevices of the reef itself. So, it looks to the moray eel, which can easily slip into these nooks and crannies.

"The trout's collaboration appears to be relatively special, as it uses gestures to coordinate its hunts with partners of different species, such as morays, napoleon wrasse, and octopus," lead study author Alexander Vail of the University of Cambridge in England said in a press release.

But could these fish pick out hunting allies that are better than others? Vail and his team of researchers set out to find out. According to the Los Angeles Times, they set up a behavioral experiment in which the prey was either out in the open or in a crevice, and the trout had to decide whether or not it was beneficial to recruit help from a fake eel conveniently positioned nearby. The scientists found that the trout made the right choice to collaborate if the fish was hiding, and to swim solo if it was exposed.

Vail and his colleagues then decided to take it one step further, and made some of their fake eels "good" and "bad," meaning they would, respectively, go for the fish or swim away. Sure enough, the trout soon learned to pick the more helpful eels.

Chimps are often thought to share complex behaviors - such as choosing allies wisely - but this new research shows that fish, too, are capable of higher intelligence, hinting that cooperation may have evolved among other species in which it was deemed necessary.

"Our study thus strengthens the case that a relatively small brain (compared to warm-blooded species) does not preclude at least some fish species from possessing cognitive abilities that compare to or surpass those of apes," the researchers wrote, "provided that the situation is ecologically relevant to them."