What do you think of this fact?
Snapping shrimp are only a few centimeters long. Still, they make a proper bang underwater when they hunt, and the noise doesn’t even come from their claw.
The bang isn’t the claw
For a long time, people assumed the typical crack came from the two halves of the big claw slamming together. In 2000, researchers from the University of Twente and the Technical University of Munich took a closer look. They filmed seven snapping shrimp with a high-speed camera while recording them with an underwater microphone.
The result, according to Physics World: when the claw snaps shut, it fires out a very fast jet of water. Behind it, the pressure drops so much that a bubble forms. As soon as the pressure recovers, the bubble collapses. That is the moment of the bang, and the shock wave is strong enough to stun small prey. The shrimp is basically shooting with water.
A flash of light in the sea
In 2001, the same team went further. In the journal Nature, Detlef Lohse, Barbara Schmitz and Michel Versluis reported that the collapsing bubble gives off a short flash of light. They called it “shrimpoluminescence”. According to the study, it was the first time this kind of light production had been seen in any animal.
For light to appear, the inside of the bubble has to get extremely hot. The authors estimate at least 5,000 kelvin, roughly 4,700 degrees Celsius. Science News compared it to the surface of the sun. You can’t see the flash, though: it is so brief and faint that the researchers could only detect it with a sensitive light sensor.
Bonus fact: According to Physics World, whole colonies of snapping shrimp make so much background noise that it can interfere with sonar.
More physics than muscle
The clever part: the shrimp doesn’t need a big body to pack this much punch. It uses an effect engineers call cavitation, which they mostly dread because it damages ship propellers. Where humans fight bubbles, this animal turned them into a weapon.
A few centimeters of shrimp, one claw, and a bubble that briefly burns like a star.