3…2…1 Bang!

The Bullseye Snapping Shrimp, Alpheus soror, is under the family Alpheidae of caridean snapping shrimp. The general body of a Bullseye Snapping Shrimp is pale orange/yellow coloured and has bright purple claws and legs. It can be easily differentiated from other shrimp species as they have a distinct large deep red spot encircled by a broad white at the centre of both sides of its body. They are commonly found in environment with sand and rock caves.

They are nocturnal creatures which hides under rocks in the day and search for food at night. The interesting aspect is that their claws are larger than their bodies, shaped like pistols. The claw is segmented into two parts, where there is a joint which allows the ”hammer” part to move backwards into a right angled position.

The reason why they are also named as the pistol shrimp is that just by snapping their claws, it will result a jet of water to shoot out at a speed of 100km/hr. Thereafter, a low pressure bubble will be generated and when the pressure is stabilised, the bubble will collapse thus producing a loud bang.

The sound emitted can go up to 218 decibels, which is louder than a jet. In addition, the force created by the claw when it opens and shuts is comparable to a bullet being shot out of a gun, travelling a distance of approximately 4cm. This behaviour is commonly displayed to stun its preys with the loud sound produced, or to kill small fishes using the pressure created. Hence, this has made the snapping shrimp the smallest yet strongest creature in the marine sea. However, as the whole process happens over a split second underwater, the loud bang is being masked, thus only be heard as a ‘pop’ to human beings.

Other source (similar behaviour found in dolphins) :

”Dolphins ‘use sonic booms to kill prey’,” by Robert Uhlig. The Telegraph, 1 February 2001

URL: http://www.telegraph.co.uk/news/worldnews/northamerica/usa/1320601/Dolphins-use-sonic-booms-to-kill-prey.html (assessed on 9 April 2013).

References:

”Alpheidae”. Wikipedia, the free encyclopedia, 24 March 2013

URL: http://en.wikipedia.org/wiki/Alpheidae (assessed on 8 April 2013).

”Alpheus Soror, A new snapping shrimp cryptospecies from Sri Lanka, ” by A.J. Bruce. The Raffles Bulletin of Zoology, 1999

URL: http://rmbr.nus.edu.sg/rbz/biblio/47/47rbz453-463.pdf (assessed on 8 April 2013).

” Snapping Shrimp stun prey with flashy bang,” by John Roach. National Geographic News, 3 October 2001

URL: http://news.nationalgeographic.com/news/2001/10/1003_SnappingShrimp.html (assessed on 8 April 2013)

Video:

” Pistol Shrimp sonic weapon- Weird Nature- BBC,” by BC. BBCEarth YouTube Channel, 16 January 2009

URL: http://www.youtube.com/watch?v=XC6I8iPiHT8 (assessed on 9 Aril 2013).

Image:

”Special relationships: Keeping pistol shrimps and gobies,” by Haplochromis. Practical Fishkeeping, 12 September 2012

URL: http://www.practicalfishkeeping.co.uk/content.php?sid=5250 (assessed on 9 April 2013)