Southeast Volusia Audubon Society, P.O. Box 46, New Smyrna Beach, FL 32170;   president@SEVolusiaAudubon.org


November 2012 SJRWMD Update


The Bigclaw Snapping Shrimp

The bigclaw snapping shrimp is arguably the closest thing to an Indian River Lagoon denizen, seemingly gifted with superpowers.


One of 11 species of snapping shrimp in the lagoon, the bigclaw snapping shrimp (Alpheus heterochaelis) is the largest and most colorful member of the pistol shrimp family in the southeastern United States. A mere two inches in length, the bigclaw is typically a translucent green hue, marked by bright orange and blue along its legs, claws and tip of the tail.


Bigclaws are easily identified by the greatly enlarged snapping claw, used in displays of threat to other snapping shrimp, self defense, and most important, in stunning and killing prey. The snapping claw of the bigclaw may grow to half its total body length and is located on either arm of the body.


The bigclaw’s diet isn’t remarkable. It subsists primarily on a variety of worms, small fishes and other crustaceans. However, it is the actual feeding behavior of the bigclaw snapping shrimp that has made it a superpower. While the concussive force generated by its claw snap is sufficient to stun or kill small prey at close distance, the snaps produced by large shrimp are strong enough to break small glass jars or even aquarium glass.


It was believed that the sound was produced by the rapid closing of the claw in motion. However, high-speed imaging has revealed a number of surprising findings. Snapping is accomplished by a shrimp’s cocking open the moveable part of its claw, referred to as the “plunger,” and building tension in a second muscle. When this muscle contracts, the plunger snaps into a socket in the fixed portion of the claw, an action among the fastest ever recorded in the animal kingdom. A jet of water is displaced from the socket and released at speeds of up to 62 miles per hour, producing a cavitation bubble capable of killing nearby prey.


The bubble is extremely short-lived and collapses by imploding within 300 microseconds of formation. The implosion produces not only a snapping sound, but also a brief and intense flash of light. Analysis of shrimp bioluminescence, or shrimpoluminescence as it has been dubbed by researchers, revealed that extreme pressure and temperature conditions exist at the time of bubble collapse, with one author indicating that temperatures around the cavitation bubble is about 5,000 degrees Kelvin (or 8,540 degrees Farenheit).


Bigclaw Snapping Shrimp
The bigclaw snapping shrimp is a large and colorful shrimp whose claw snap can break a small jar or even aquarium glass.


Photo provided by The Southeastern Regional Taxonomic Center, South Carolina Department of Natural Resources