Blue Tip Acro Question !!!

[civicdemon]

So I have this blue Tip acro that I got about a month back and I have never really noticed the polyps out ever, but at the same time I can see it growing. a couple nights ago I was looking in the tank and the polyps where out and flapping around. Do these corals mainly feed at night ??? I know most sps grow with the light but why no polyps during the day ??