A shrimp punch boils the water
The peacock mantis shrimp’s club strike is so fast it cavitates seawater. The bubble collapses and adds a second blow, with a brief temperature of thousands of degrees.
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Saddle-shaped springs in the limb store energy and release it faster than muscle can contract. The club hits at tens of metres per second. Pressure drops behind the face, a vapor bubble opens, and the collapse sends a shock. Prey — snails, crabs — meet two impacts for one swing.
The light sometimes seen is sonoluminescence from the collapsing bubble, the same family of physics as a pistol shrimp’s snap. The club itself is a layered composite that does not shatter. Materials labs study it because the animal solved impact better than most ceramics.
Caveats
- The extreme temperature is inside a tiny, microsecond bubble, not a lasting flame.
- Speeds and forces vary by species. The peacock mantis shrimp is the measured case.
Sources
- 1Patek S. N., Korff W. L., Caldwell R. L.. Extreme Impact and Cavitation Forces of a Biological Hammer. Nature 428, 2004.