>I have observed this in a shorthead redhorse in an aquarium. It's >loud.
>You could hear it all the way across the room. The fish was >only about
>six inches long. Kind of sounds like a rock striking >another rock.
>That's what I thought is was at first, but I started >watching and caught
>him it the act. I think it was just mouth >movement. Do they have
>otoliths or some sort of membrane that could >produce the sound?
Suckers (and minnows) don't have jaw teeth, but have "teeth" located at the
back of the throat. In some suckers (Moxostoma carinatum, M. valenciennesi),
the teeth on these structures are large and blunt, similar to your molars.
In others, they are thin and comb-like. They operate these teeth against
each other, and against a hard, ossified (bony) pad that lies against the
base of the skull. That's probably what the noise is from.
Correct me if I'm wrong (Jan, Chris, Bruce, others), but in suckers, the gas
bladder serves more as a sound receptor than an amplifier. In some others
(drum?) they can produce noise using the gas bladder.
Almost all fish have otoliths, but they are small bones in the inner ear
that don't play a role in sound generation, only detection.
best,
Dave
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