Jacks hunt in groups on the outer reef edge, and alone when shallower.
Their hunting behaviour has 4 phases-
Patrolling, when they make no predatory moves
Quatering, zig-zag moves at high speed
Hunting, when it identifies a victim
Attacking, when within striking distance, moves in for the kill
The jack has a protrusible jaw,and the prey is sucked in. Fish which are the Jacks prey recognize and adapt to these 4 stages. The prey ignore the Jack when patrolling, but immediately seek shelter when quatering starts. Once a kill has occurred the other prey return to the open reef and resumed their foraging. This explains why divers see prey and predator swimming near one another in apparent peace.(watching fishes by R.& J.Wilson)