Help with Duncan Coral!

[Squidly]

Hey everyone, as you can see I'm havin a little trouble discerning whether or not my Duncan is in good shape. I'm not quite sure what a normal Duncan's behavior is but lately it's been randomly closing it's heads and doesn't look quite as peppy. My parameters are all in check with the exception of my nitrates a little higher than wanted at around 10, temp 79, Duncan placement: mid tank, mid/ light flow and stock biocube lighting. Here are some pictures and I would just like some confirmation on how this Duncan is doing thanks!
A week ago....

Today....

 

[Sniperhank]

Duncans do that. If they grab something small to eat they can retract in a similar manner, or for no reason at all. Mine does it all the time. It is doing fine, just keep your parameters in check by lowering your nitrates.

 

[Squidly]

Thanks for the reply it looks good today I just didn't know what was going on its a pretty strange piece. I just wanted to make sure this was normal behavior.