Less than 10 centimeters long, the few dozen species of snapping shrimp may not look like formidable foes. But their lightning-fast claws close so quickly that they make sounds louder than a gunshot, and create shock waves in the water that stun fish, worms, and other prey. But the evolutionary steps from simple pinching to ultrafast snapping were a mystery to scientists. Now, a team of biologists has closely examined the claw anatomies of 114 species of shrimp, including about a dozen known snapping species. As they report in Current Biology, they found two new types of claw joints heretofore unknown to science. The first was a simple slip joint—common in many pocket knives—in which a tiny ridge helps keep the claw open until enough pressure snaps it closed. This allows the claw to close a bit faster than usual. The second was an even further modified version called a cocking slip joint, where the ridge fully cocks the claw open. That allows snapping shrimp to build up incredible tension in the claw’s muscles before a secondary muscle movement releases it, slamming it shut at ultrafast speeds and generating a shock wave. Now who are you calling “shrimpy”?