Why do zoa's sometimes close for a little bit and then reopen shortly after?

[Korrine]

Even when it appears nothings been crawling on them they sometimes close and reopen. Anyone know why? It's mostly a sea foam paly and alpha omega.

 

[Korrine]

Various succession pictures taken within a few minutes.

 

[650-IS350]

water flow passing around them.

 

[Korrine]

really. that's it?

 

[Reef Bass]

Probably. Plus the gleeful evil rush they get as they observe your reaction.

Ok, that's silly, but it sure seems like it sometimes...

 

[Korrine]

oh ok. Thought maybe there was more to it. Thanks

 

[Reef Bass]

As a side comment, I don't always see the critters themselves when they're irritating. For example, on a colony of open zoos, one cannot see past the skirts. The "forest" of trunks has a lot of open space beneath the skirts and critters will crawl around in that space without you being able to see them. What I notice is a path of twitchy / opening and closing zoos as an amphipod or bristle worm moves through the colony.

 

[Korrine]

good point. mine aren't that big...yet. Just a few heads on them.