It's been a while since I've studied them, but I think they can generate a force equal to a
There are two types of Mantis shrimp attacks. The "spearers" and "smashers". The smashers have the fastest known attack of any animal known to us at the moment, and until recently the fastest known voluntary motion of any animal. Their clubbing appendages accelerate over 10,000g. Even if they don't directly strike their prey, the shock wave of the bubbles (created by cavitation) collapsing will kill their prey. If they don't miss, they first get hit by the shrimp and then again by the shock waves.
Mantis shrimp also have the most complex eyes of any known animal. Over all a really cool critter. I've kept them in aquariums, and they adapt well and will learn to recognize you after a short period of time and shed their shy nature. But they can be a nightmare if they end up in an aquarium as an unwanted hitchhiker. They usually kill the most expensive inhabitants first.