Pistol-powered Shrimp

What sea creature has lopsided claws, is barely as long as your little finger and yet is among the noisiest animals under the sea?

The evocatively named snapping shrimp or pistol shrimp can be found across a wide range of the world’s oceans and gives sperm and beluga whales stiff competition for the title of loudest marine animal. The noise comes from a claw snapping movement which is so powerful that it serves as a formidable blasting weapon.

Smooth Snapping ShrimpPistol shrimp, known to science as Alpheidae, are asymmetric: they have one small claw and one extra large claw which does the snapping (the enlarged claw reminds me of cowboy Woody’s overstuffed bicep after he is torn and repaired in Toy Story 2). The snapping claw closes forcefully, sending out a pulse strong enough to knock out the pistol shrimp’s prey. Wikipedia describes the claw snapping action in this way:

The animal snaps a specialized claw shut to create a cavitation bubble that generates acoustic pressures of up to 80 kPa at a distance of 4 cm from the claw. As it extends out from the claw, the bubble reaches speeds of 60 miles per hour (97 km/h) and releases a sound reaching 218 decibels. The pressure is strong enough to kill small fish.

As these bubbles collapse they grow very hot, briefly reaching a temperature which almost matches the surface of the sun and creating a tiny but intense flash of light which cannot be seen by the human eye. Not bad for a crustacean which is no more than 5cm long!

Photo credit:
Ria Tan www.wildsingapore.com/wildfacts/

Archived under Science & Nature.

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