# Fish stones (Otoliths)



## Lukikus2 (Mar 29, 2011)

Ya'll ever cut the stones out of a drum's head? They look almost like ivory. I was told they rub the stones together in their head to make the drumming sound. Cool fact of nature.


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## jason4445 (Mar 29, 2011)

I just saw a  thing on TV about Redfish (Red Drum) and it said that all drums used a muscle to make the sound - I looked it up and drums have a certain muscle called the sonic muscle that hits up against their swim bladder that makes the sound.  Mostly it is a mating call, but also can be used in times of stress as a warning signal.  It puts out a low frequency sound that travels well through water.

The stones in a fish's head and most fish have them, generally serve in a sensory system and sit atop a mat of sensitive hairs and their sloshing around gives the fish information about its movement in space. Fish that have to deal with complicated spatial environments (reefs, kelp beds) usually have bigger stones and  those open water predators that stick to swimming fast in straight lines (tuna, billfish) tend to have relatively small ones. The stones also seem to play a role in underwater hearing in many species: because they are stone (and therefore of a different specific gravity than the rest of the fish), their vibrations in response to sound waves are out of phase with those of the animal's body; these differences can be translated into acoustic information.


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## jcinpc (Mar 30, 2011)

those saltwater cats have little pearls in a cavity in their skulls. after a red tide I always go down to certain beaches and pick them out of the heads.


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## drippin' rock (Mar 31, 2011)

jason4445 said:


> I just saw a  thing on TV about Redfish (Red Drum) and it said that all drums used a muscle to make the sound - I looked it up and drums have a certain muscle called the sonic muscle that hits up against their swim bladder that makes the sound.  Mostly it is a mating call, but also can be used in times of stress as a warning signal.  It puts out a low frequency sound that travels well through water.
> 
> The stones in a fish's head and most fish have them, generally serve in a sensory system and sit atop a mat of sensitive hairs and their sloshing around gives the fish information about its movement in space. Fish that have to deal with complicated spatial environments (reefs, kelp beds) usually have bigger stones and  those open water predators that stick to swimming fast in straight lines (tuna, billfish) tend to have relatively small ones. The stones also seem to play a role in underwater hearing in many species: because they are stone (and therefore of a different specific gravity than the rest of the fish), their vibrations in response to sound waves are out of phase with those of the animal's body; these differences can be translated into acoustic information.



That's some of the best explaining I've heard in a while.  Never knew anything about them, now I do! Thanks.


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## drippin' rock (Mar 31, 2011)

jcinpc said:


> those saltwater cats have little pearls in a cavity in their skulls. after a red tide I always go down to certain beaches and pick them out of the heads.



What do you do with them?  Do you have pics?


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## Lukikus2 (Apr 1, 2011)

Thanks for the true definition Jason4445. 

I only thought they were in freshwater drum. Now I'm learning something new. After some research I found they are actually called Otolith's. Here are a couple of pictures. The last picture shows the coloration of them but the ones I have found were smooth on both sides not all jagged as shown. And the larger the fish the larger the Otolith. Cool Huh!


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## rvick (Apr 1, 2011)

yall are learnin me sumpin', i've seen beazle stones in deer but never stones in a drums head, sort of along the lines of crystals in our inner ears?


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