The coral trout collaborate with moray eels to hunt for prey. A new study showed Monday that coral trout are choosy when it comes to picking the best hunting partner. The study conducted by scientists at the University of Cambridge showed that collaborative abilities are not limited to humans and apes. Findings of the study were described in the journal Current Biology

Coral Trout

Why do coral trout chose members of other species as hunting partners?

Alexander Vail, lead author of the study, said in a statement that the coral trout’s collaboration is quite special. It relies on gestures to coordinate with partners of different species such as octopus, napoleon wrasse, and morays. Those other species are more useful to the trout as a hunting partner than members of its own species (i.e., other coral trout). That’s because these other species can easily flush the prey out of reef crevices, which is pretty difficult for the trout.

Of course, the fish can’t pull out a stick to pry the prey out of crevices. They use signals and gestures to flag the location of the prey to its hunting partner. A study showed in 2006 that chimpanzees work with other members of their species, taking on different roles such as blockers or chasers, to hunt in the wild. Chimpanzees too make careful choices when selecting the hunting partner.

Coral trout can identify a good partner from a bad one

To conduct their study, researchers caught some coral trout and brought them to the lab to see how they interact with moray eel decoys. Scientists created set-ups that mirrored the natural environment of the trout. One eel was a good hunting partner and the other was a bad one. Their collaboration behavior was tested in six trials a day for two consecutive days.

During the first day, the coral trout were gauging the effectiveness of their collaborators. So, they chose each collaborator and, surprisingly, an equal number of times on the first day. But on day two, they chose only the good hunting partners. When the coral trout signaled, the good moray came to flush out the prey, while the bad one would immediately swim in the opposite direction.

Findings of the study strengthen the case that a smaller brain, compared to warm-blooded animals, doesn’t stop some fish from having collaborative abilities.