# Would a Giant Pistol Prawn Snap work in the air?

I'm getting a giant unrealistic crab to be capable of reproducing the pistol shrimp's snap with their claws? pincers?. Anyway I want to know whether there is a way to let this be a weapon on land.

I understand that since it won't be snapping underwater, it won't be able to do the same thing in the air but I think it might still be able to make a loud sound and shockwave from the snap? With enough force, the shockwave can stun or kill humans actually[Could not find any statistics talking about this], not sure how the crab would survive but meh.

Firstly, I would like to know what it would do in the air with a giant washing machine sized claw?

Secondly, any methods to make this more lethal but preserving the claws shape?

• I strongly doubt it, because air is more compressible than water, and this makes creating strong shockwaves harder. Sadly I can't find science article that would allow me to support my doubts. Aug 20, 2016 at 7:53
• Water is 784 times denser than air. The bullet fired by the shrimp moves at a velocity of 97 kilometers per hour, that's almost 4 times slower than the average arrow. However to reproduce at least a bullet of 97 kilometers per hour in air your shrimp would need to be 784 times stronger than normal shrimps. And does bigger mean stronger? I don't know... Aug 20, 2016 at 10:01
• @Motot I have to agree with you. If it could create a very loud sound wave that would work (maybe) but that is not how a pistol shrimp works. Aug 20, 2016 at 10:27

The effect of this is going to be pretty limited. Without knowing the size and strength of the giant crab, you can't get numbers, but a ballpark upper limit would be firing a low-powered pistol with a blank cartridge. This makes a loud noise, can startle and frighten, and can do minor damage at very close range, but just snapping the claw closed on a creature would do far more harm than the sound.

The way it works underwater requires water. Moving the claw very quickly creates a low-pressure area in the space the claw is moving out of. In fact, the pressure is so low that some of the water evaporates into vapour, creating bubbles. This is called "cavitation", and it's important for any fast-moving underwater object, such as ships' propellers. The collapse of such bubbles converts a lot of the energy that went into producing them into very brief, and thus loud, sounds. You can't do this in air, because you can't change air into something else via low pressure.

• Right, the mechanism won’t work in air. Aug 22, 2016 at 8:37