Reef fish uses sign language to catch prey


The roving coralgrouper uses sign language to advise fellow hunters of hiding prey, according to a study published Tuesday.

Reporting in the journal Nature Communications, three biologists studied how the coralgrouper works with two hunting pals. Previous research has shed light on the unusual relationship between the coralgrouper, the giant moray eel and the Napoleon wrasse.

By cooperating, the three species maximize their chances of getting dinner. The grouper has “burst speed” to capture prey in open water, while the eel can slide into crevices where small fish lurk and the wrasse has powerful extendable jaws that can suck out prey from a hole.

The grouper has two signals it uses in these hunts, according to the paper. The first is a “high frequency shimmy,” or a kind of body shake, that it performs in front of the moray as a general invitation to join it in a chase.

The second is specific, or “referential.” It is a headstand, which the grouper performs vertically and head-down, indicating to the moray or the wrasse where a prey is hiding or where it was last seen.