BTA shrinking at night. Is this normal?

[Subnautica]

All my BTA's shrink to a very small size at night, when all the lights are off.

If this is what happens in the wild, then where do the clowns sleep?

 

[blaxsun]

Yes, perfectly normal. My clownfish still harass the closed anemone.

 

[aggrofish]

Yup some will look identical to a pineapple where there are just a few tentacles poking out the top. The size difference between closed at night and mid day is huge.