Margen
The mantis shrimp keeps a pair of club-like limbs folded under its body and fires them like a loaded spring. The blow launches with an acceleration comparable to a bullet leaving a pistol, and the whole thing happens in under three thousandths of a second.
It moves so fast the water can't get out of the way: vacuum bubbles form and, as they collapse, release a flash of heat and a second shockwave. So even if the club never touches the prey, the burst alone is enough to stun it. A single strike can crack a crab's shell or the glass of an aquarium.
And it does this over and over without wearing the mechanism out, thanks to an elastic structure spread through its shell. A boxer under twenty centimetres long that lands two hits with a single punch.