Fish have the ability to communicate with each other while hunting their prey in ways that were previously known only for humans, great apes, and ravens, according to new research.
Scientists have discovered that groupers and coral trout perform a pointing signal to indicate the location of hidden prey to co-operative hunting partners including moray eels, octopuses and Napoleon wrasses.
Previously it was only known that humans, great apes and ravens were capable of such communication and the signals were taken as further evidence of their complex and comparable cognitive abilities.
Researchers observed dozens of events where groupers and coral trout performed upside-down headstands with concurrent head shakes to indicate the presence and location of particular prey to co-operative partners.
They also observed that the grouper elaborated on its headstand signal if another predator - for example a moray eel - did not react appropriately. The grouper would swim over to the eel, trying a different signal and in some cases even attempting to push the moray in the direction of the prey.
The grouper's signalling shows what are considered key hallmarks of being carried out with intent - that is, the fish has a goal in mind and uses communication to try and achieve it - rather than being an inflexible gesture.
Groupers were observed to wait above hidden prey for up to 25 minutes before signalling to a passing predatory partner. This suggests groupers may perform at an ape-like level in a memory task commonly used to assess cognitive ability.
The study was led by Alexander Vail, a Gates Cambridge Scholar at the University of Cambridge's Department of Zoology, and the research paper, "Referential gestures in fish collaborative hunting", is published in Nature Communications. You can find more information on the University of Cambridge's website.
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