can't figure out?

[reefer44]

I have 5 sps corals in my tank all have been in there since sunday but two of the acroporas haven't opened there polyps today! the other days they were fine but they wont open up even theough they are under good light and almost perfect perimeters. The only thing different is on of the clown gobies keeps sitting on them would this cause them to retract polyps?
Any response is helpful Thanks
Brad

 

[dad]

Yes this can cause them to close. It may be a defense or there way of capturing food?
Either case...yes, HTH