Clam seems great, mouth not open?

[carolinareefs]

I purchased my first clam last week from reefscience.com (great experience by the way) and put in the tank last friday. It has been in a week and I am not sure if the mouth not opening is normal or not. The clam is fully open, mantle extension is fine, it expels waste, reacts when a fish swims above it or I put my hand in between it and the light source, and closes up at night.

I am just not sure if it is normal or I should be concerned. Sometimes the bottom of the mouth opens, but not usually the whole mouth.

Any advice would be appreciated. (I am out of town right now so I cannot post water parameters until Monday. Just want to know if this is something I should be concerned with.)

[surgeonboy]

If the mantle is extended and there's no gaping ( wide open mouth) then it's doing fine.
What kind of clam do you have?

[carolinareefs]

Sorry. It is a 4-5" derasa clam.

[bhdmc]

As long as the mantle is fully extends and it reacts when a fish swims near it, you are fine.