Snapping Shrimp: Louder than a gunshot

There is a small shrimp that belongs to a family of shrimp called the Alpheidae that is only about 2 cm long that can make a sound louder than a gunshot. It is called the Snapping Shrimp or sometimes the Pistol Shrimp.

Snapping Shrimp
http://aquaviews.net/wp-content/uploads/2009/09/snapping-shrimp.jpg

They stun their prey but snapping their claws together to make a crack at 218 decibels - which is louder than a gunshot. The sound stuns the prey and allows for the shrimp to go in for the kill. The noise is not caused by the claws hitting each other but by a jet of water that is created by the impact. The tiny stream of water spurts out at 60 mph which creates a low pressure bubble in its wake. When the bubble collapses it makes a bang louder than a rocket launch or a jet engine. Also for a tiny fraction of a second, the temperatures in the bubble can reach more than 4400C. The popping also creates a flash of light daily mail which lasts for about a billionth of a second. Rivals compete against each other by seeing who can make the loudest noise and if the larder claw becomes damaged in a fight, the smaller one grows to replace it. There are about 600 species of snapping shrimp world wide. (dailymail)

Signaling between snapping shrimp includes chemical and chela (claw) displays. Both males and females perform a visual signal which is an open chela display in both aggressive and pair-forming interactions. The shrimp responds according to the sex of the other shrimp and they use chemical signals to do it. Snapping shrimp are burrow dwelling and very aggressive in defending those burrows against same sex intruders. The larger animals most often win out but smaller animals have a greater chance of winning if there is a small difference is size. The interactions between same sex shrimp can get very dangerous and escalate quickly and can end up in serious injury of death. Snapping shrimp have asymmetric chelae and the size of the larger chela is proportional to the size of the shrimp. The body sizes of opposite sex pairs are highly correlated so body size is important when pairs are formed for the snapping shrimp. The interactions between snapping shrimp frequently begin with contact by one or more of the animal's antennae. They also bring their chelae into contact with the other shrimps body. The antennae are thought to transmit chemical signals important for pair formation by transmitting signals that have sex information. (Hughes)

Slow motion pistol shrimp attack

https://www.youtube.com/watch?v=QXK2G2AzMTU

The snapping shrimp is an incredible animal that has an amazing way of capturing prey. The fact that such a tiny animal can create such force is mind boggling. The way that the claw is shaped has a lot to do with how it is able to create a large bubble and make a deafening noise. They manipulate the flow of the water with their and are able to make the two parts of their claw come together and create a vortex of sorts in order to stun their prey. (Hess) They are a fascinating animal.

Sources:

Hughes, Melissa (1995) The function of concurrent signals: visual and chemical communication in snapping shrimp. Animal Behavior, 52 247-257.

http://www.dailymail.co.uk/sciencetech/article-1085398/Deadly-pistol-shrimp-stuns-prey-sound-loud-Concorde-UK-waters.html

Hess, David, Christoph Brucker, et al. (2013) Vortex formation with a snapping shrimp claw. Plos one.