This fish recruits moray eels to hunt for it, and the work that showed it was done here.
A grouper hunts in open water; a moray hunts inside the reef. Neither can reach where the other can, and a small fish escapes each of them by going where the other one is. So the grouper goes to a moray resting in its hole, puts itself head-down in front of it, and shakes its whole body rapidly. The moray comes out. The two then move over the reef together, and prey flushed out of a crevice by the eel is taken by the grouper in the open, while prey driven into the rock by the grouper is taken by the eel inside.
It gets better. When prey hides in a hole the grouper cannot enter, the grouper holds a headstand directly over the spot and shakes its head at the eel. That is a pointing gesture: a signal that refers to something in the world rather than to the signaler, which outside of this had been documented in very few animals, most of them primates and ravens.
Both fish do better on joint hunts than alone, and groupers learn which partner is worth recruiting. This animal lives in the 🌊 Red Sea and nowhere else, and it was long filed under the name of its 🌊 Indian Ocean relative.
The genus. Plectropomus Oken 1817 - plectrum (spur) + pomus (lid or covering). ETYFish
- gray-brown to deep red with pale bars down the flank
- large, up to 90 cm, and heavier through the body than a lyretail
- usually inside a cave or under an overhang during the day
- found in the Red Sea and nowhere else
Why it's threatened
Overfishing is a major threat to this species, and targeted effort on spawning aggregations causes rapid population declines (Elamin 2012, H. Choat pers. comm. 2018).
Threat classification from the IUCN Red List.
