Snap, crackle and pop

A specimen of snapping shrimp of the genus Alpheus.
Image: Arthur Anker.


24 May 2010
The snapping shrimp studied by Dr Art Anker of the Florida Museum of Natural History are bubbly creatures – they create bubbles for stunning prey, self-defence and communication.
Dr Anker's focus on the CReefs Ningaloo expedition is the shrimp family Alpheidae, also known as snapping shrimp.
The typical alpheid shrimp feature is an oversized claw that possesses a snapping mechanism – hence the name – almost like clicking their fingers. The claw can issue a jet of water and make a cavitation bubble, which the shrimps "pop" to create a shockwave strong enough to stun or injure other organisms.
"If they catch a little worm and it wriggles around, they just snap a few times to stun it," Dr Anker explains.
However, the snapping can be used also for self-defence or for defence of the shrimp's territory or domicile.
"When the crown-of-thorns sea star, Acanthaster, tries to crawl over coral where alpheid shrimps live, the shrimps, along with some crabs sharing the coral head, pinch and snap very aggressively until the sea star goes away," Dr Anker says.
Alpheid shrimps are extremely abundant on coral reefs and much of the crackling noise heard underwater is due to their snapping. There is even a theory that the noise of snapping shrimp may assist turtles and large marine mammals such as whales to find their way to coral reefs.
Dr Anker also believes that alpheid shrimps may also snap to communicate with each other.
Some alpheid shrimps play an important role in bioerosion – the term used for reef damage due to biological (mostly animal) activity – and renewal of reefs.
"Many of them are reef destroyers. They bore into both living and dead coral. It degrades reefs, but also clears away dead coral and allows new life to grow, and creates new microhabitats, so it's a very important process," Dr Anker says.