a silent aquarium

A crayfish defence system depends on the tiny hairs that cover the surface of its body. They function in much the same way as the hairs inside the cochlea of the body of a human ear, detecting extremely faint, almost inaudible sounds that may be the hungry turtle. The odd part of the story is that these hairs won't work if there's too much silence. Put a crayfish in a silent aquarium, add a turtle and it gets eaten, but add some random background noise to simulate the crackling and popping, we can hear on underwater recordings made with hydrophones and the crayfish escapes.

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