Bivalves leaving their rock?

[Devilishturtles]

Hi guys.

I have (or rather had) two bivalve species (one a suspected turkey wing clam) for more than 2 years. They came in on a piece of live rock. About a month ago, my largest bivalve detached from it's foot and was upside down on the sandbed. I picked it up and put it right side up on the sand bed. It is still alive now... and it's hard, yet fleshy foot is still attached to the rock. When I touch it anywhere near it's muscle parts, it retracts. I've tried putting the bivalve back over the foot to see if it will attach again, but it will not.

This afternoon, I came home from work to find my turkey wing clam detached from it's foot and on the sand bed. This time however, it was jacked wide open, and completely clean on the inside. Someone made a tasty snack of it. Everything is fine. Water is testing perfect and consistent.

I'm just wondering why they came detached, and only one died. I know they are hard to keep alive, because of their filter feeding habits...but mine have been thriving for more than 2 years. Is there an instinctive reason that they leave their spot?

Thanks for the input.

 

[Fluff]

I don't know why they detached DT but I can say two/three years is when mine started to die off. And what you are explaining is exactly what happened with mine. This leads me to believe that it's natural and they just don't live for many years. :?

 

[Devilishturtles]

Thanks Fluff. This is what I was fearing. I will keep an eye on the large bivalve and see what happens.