11 December 2006

Vox Shrimpo

Actually, it's more likely to be along the lines of vox malacostraca , but no matter.

What's the loudest thing in the ocean?

The blue whale might produce the loudest noise of any individual animal in the sea or on land, but the loudest natural  noise is made by shrimps. Pin back yer lug 'oles and learn:

  • The sound of the "shrimp" layer is the only natural noise that can white out a submarine's sonar, deafening operators thru their cans.
  • The noise of collected shrimps adds up to 246 decibels. Even allowing that sound travels five times faster in water, this equates to approx 160 decibels in air, louder than the 140dB of a jet taking off or the human pain threshold.
  • Imagine everyone in the world frying bacon at the same time.
  • Howzit done? Eh bien (or 'Lipon', as the Greeks say) - it comes from trillions of shrimps snapping their one oversized claws all at once. But wait, it gets more interesting:
  • Video shot at 40,000 frames per sec show that the noise occurs 700 microseconds after   the claw has snapped shut. The noise in fact comes from burst bubbles.
  • A small bump on the side of the claw fits into a groove on t'other side. The claw shuts so fast that a jet of water squirts out at 100 km per hour, fast enough to create expanding bubbles of water vapour. When the water slows and normal pressure is restored, the bubble collapses, creating heat as high as 20,000°C, a loud pop and light (new word for you, chaps: 'sonoluminescence', where sound generates light).
  • Shrimps use this to stun prey, communicate, and find mates (as well as buggering up sonar, the sharp noise also makes dents in ships' propellors)
  • No comments :