This means that the prey is hit twice by a single strike ; first by the claw and then by the collapsing cavitation bubbles that immediately follow . The collapse of these cavitation bubbles produces measurable forces on their prey in addition to the instantaneous forces of 1,500 newtons that are caused by the impact of the appendage against the striking surface , which means that the prey is hit twice by a single strike ; first by the claw and then by the collapsing cavitation bubbles that immediately follow .