The strike is a spring-loaded mechanism, not a muscular punch. A saddle-shaped section of exoskeleton is compressed and held by a latch while slow muscles load it, and releasing the latch delivers the stored energy in about three milliseconds. Recorded club speeds reach roughly 23 metres per second from a standing start, among the fastest limb movements measured in any animal.
At that speed the pressure behind the club drops below the vapour pressure of water and a cavitation bubble forms. When it collapses it releases a shock wave, a brief flash of light known as sonoluminescence, and localised heating. The consequence is that a mantis shrimp can crack a snail even when the club narrowly misses, and captive animals have broken aquarium glass.
The eyes attract equal attention and are more often misdescribed. Peacock mantis shrimp have twelve or more classes of photoreceptor, but behavioural tests show they discriminate wavelengths less finely than humans do. The current interpretation is that the extra channels support fast, simple colour recognition rather than a richer colour experience.