Brain shrinks at night

I have an open green brain, I noticed just recently that in the early morning it has shrunk down to about 1/3 of it's size, looking like a large raisin. Later in the day it expands and looks fine. Since pH drops at night is this the cause? Is there anything I need to do?

 

Heh... This happens to NY brain after a long night out...

Actually, during the day your "brain" coral, which could be any of a number of species, is photosynthesizing, and creating food from light. It is passivly eating so to speak. At night, there is no need for it to be inflated, because it doesn't need the surface area to absorb light, and so retracts, and usually there is active feeding that takes place during this time to capture some sort of prey through the use of nematocysts.

Bottom line: Don't worry it's normal behaivior for any coral to deflate in the evening.

 

Most corals retract at night somewhat. My frogspawn is out with its tentacles flowing during the day. At night they retract. I did see sweeper tentacles (second time) the other night after they retracted. My Xenia and zoas close their polyps, my mushrooms look all wrinkly, and the polyps on my leather close up and it kind of droops. As soon as the lights come on, everything comes back out again and is lively as ever. I wouldn't worry as long as it looks happy during the day.