Bigclaw Snapping Shrimp (AKA Pistol Shrimp)

Bigclaw Snapping Shrimp (Alpheus heterochaelis)

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(c) Guy 2015

 

  • Collected in April 2015 in the Upper Reach of Sapelo River, GA
  • AKA “Pistol Shrimp”

Otherwise known as one of the neatest critters in the estuaries you probably didn’t know was there.

The common name, pistol shrimp, comes from the way these shrimp use their enlarged claw (which can be either on the left or the right). The shrimp cocks its claw like a pistol when it sees its prey, aims, and ‘fires’ by closing it quickly.  This rapid closing forces water through the claw so fast it creates a large amount of sonic pressure, causes cavitation bubble that ‘implodes’. This directed pressure wave is enough to kill or stun a small fish.  It happens so fast, at such high pressures, that it superheats the water for a microsecond around it to temperatures nearly as hot as the surface of the sun. This also creates a microflash of light that isn’t visible to the naked eye.

It is one of the loudest creatures in the ocean, even on par with humpback whales in decibels level.  When we picked this individual out of the net, it gave us a small demonstration of just how noisy it was.

This species of shrimp do not get much bigger than what you see in this photo (a few centimeters, or an inch or two).  They are not used as a food shrimp and are in a different family all together (Alpheidae) from the shrimp that are commonly eaten in the west (Penaeidae).