cup corals on fl LR...is someone eating them

[peterl23454]

i got some lr from gulf view...great stuff
do these die off? i've only had them for about a month now.

i thought that some were gone{polyps gone?} but the next day they were back.

that was a week ago ...now i dont see any polyps on any cups{and there is alot of them}. could something be eating them

bi color angel{never seen nipping them},2 peppermints,1 coral banded shrimp,1 mithrax crab.

the shrimp are what worries me{i just dont know what they do at night-lil buggers

[mogurnda]

On my rock, the polyps retract and extend depending on mood, time of day, feeding, etc. When you say cup coral, I assume you mean Phyllangia. Mine have occasionally retracted for days at a time, although they don't usually do it all at once. They can look completely dead when they are fully retracted. For the first several months they extended mostly at night, but seem to have figured out that food is available all day, and that nobody will bother them, and are extended most of the time.
There are several possibilities I can think of, and others will probably add to the list. Like if you have a hitchhiker or resident that's bugging them. Some of my biggest polyps disappeared for about a week after a coffee bean trivia attacked them. Water quality is a possibility, like if the new rock caused an NH3/NO2 spike, although these corals seem to thrive in polluted areas.
Because they are ahermatypic, they will need to eat. I am not sure if leftovers are enough, so I give mine IPSF "Coral Heaven" and Reed's Instant Algae a few times a week. It's fun to watch them stuff the chunks of CH into their mouths with their tentacles.
HTH

[mogurnda]

peps
My peppermints have never shown any interest in the corals, except to steal food from them. I don't think they're a problem. Can't say about the CB shrimp, but I doubt that it's your problem.

Now I'm done.

[SPC]

I agree with Dave that they need to feed sense they are ahermatypic. I have had them in my tank for over two years now and can say that the ones that don't receive food (I don't target feed them) will die eventually. The ones I have that are doing well are in an area that receives bits of food due to water current.
In your case though Peter, I would definately be leaning towards the angel bothering them.
Steve