My clownfish sucks on a tentacle on his anemone once in a while. He just sucks one up, holds it in his mouth for like 10 seconds, then lets it go. The tentacle looks fine, no marks. Why do you guys think the clown does this?
It is called "mouthing" an anemone and some folks believe it is one of the ways the clownfish is able to avoid getting stung and producing the correct mucus/slime layer to avoid getting stung.
Need to do a bit of research but most folks think it is a familiriaty ritual at the very least - clownfish meeting and greeting and saying hello to mr anemone ....