It's that noise that keeps some folks up at night when sleeping in a boat in the temperate waters of the Sea of Cortez. Some fear them for Fiberglass Termites but marine biologist Bill Martin fills us in on Snapping Shrimp or more scientifically named Alpheus heterochaelis. Bill is a retired architect with a passion that drove him to a MS in 1999 and he and his wife Jean can can often be found poking around the tidal pools of La Paz.

The snapping shrimp (Alpheus heterochaelis) produces a loud snapping sound by an extremely rapid closure of its snapper claw. It was commonly believed that the sound is generated when the two claw surfaces hit each other. Research, however; shows that the sound, in fact, originates from the collapse of a cavitation bubble. During the rapid snapper claw closure a high-velocity water jet is emitted from the claw with a speed exceeding cavitation conditions. (Cavitation is a physical process that has long plagued ships' propellers.)

These critters are really loud (the popping of the cavitation bubbles) and when colonies of the shrimp snap their claws; the cacophony is so intense that submarines can take advantage of it to hide from sonar.

The shrimp use the sound to communicate with one another and to defend their territory.  Additionally, they take advantage of the damage cavitation can do to stun their prey.  

So no worries, they will not nibble through your boat’s hull!  
We mentioned, didn’t we, that these critters are typically less than 1 inch in length?

Click here to play the sound of the Snapping Shrimp

Researched and written by:
Bill Martin
SV Talaria (Ericson 38)

21 January 2008
CostaBaja Marina, La Paz, BCS, MX
Soon to depart - to continue the search for warmer water