Tuesday, May 1, 2007

Snapping shrimps: Pop musicians of the shores

Two NAKED facts

Thoughtful question: Can you hear the little pops and snaps? Can you guess what causes those sounds? Can you guess how big the animal is?

It's made by a tiny shrimp that lives in burrows and under stones!

NF#1: Sound blaster pincers: A snapping shrimp has one of its pincers greatly enlarged. This pincer may even be as long as its entire body! The pincer has a moveable 'finger' held apart with a catch. When the catch is released, an explosive sound results.

The blast stuns prey like tiny fish and cracks the shells of small clams. It is also used to ward off predators and intimidate rival pistol prawns.

NF#2: Shrimpy friends: The shrimp goby lives in the same burrow with a snapping shrimp. With keener eyesight, the goby keeps a look-out while the shrimp busily digs out and maintains their shared home. The shrimp is literally constantly in touch with the goby with at least one of its antennae always on the goby. When the goby darts into the burrow, the shrimp is right behind it!Too Much Information

The Science of The Sound: The snapping sound is not made by the fingers actually hitting each other. Rather, a high-speed jet of water shoots out due to the extremely rapid compression of the fingers. This jet vapourises the water and creates a bubble. When the bubble collapses, the sound results. Not only that, a flash of light is also emitted!

These findings are possibly useful for naval applications as the sound of snapping shrimps seriously interfere with sonar detection in shallow seas. In fact, snapping shrimps have been studied since World War II as their sounds interfered with the detection of hostile submarines!

More snapping friends: Snapping shrimps also live in symbiosis with other animals such as corals, sponges and sea fans. The tiny (1cm) Crinoid snapping shrimp (Synalpheus stimpsoni) lives in pairs on feather stars (crinoids), feeding off the mucus of its host. It is listed among the threatened animals of Singapore.

Two snapping shrimps commonly seen on our shores...

One is smaller 4-6cm with a rounded pincer often with an orange 'finger'The other is larger 5-7cm with flattened pincers.

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