The mouth opens and closes daily. Most of the time it's locked up tight. Just before the moonlights came on tonight, all the tentacles deflated and the mouth was open. It spued some gunk (du du) from the mouth. I haven't noticed the mouth closing up tight yet but it's only been an hour.
Are there different types of Ritteri? The other one I have is brilliantly green, with the familiar cap around the base that it closes up. (check my gallery or the anemone gallery for photo).
Thanks for the info!