[Coral-List] Corals biorhythm and feeding time

[Barbara Gratzer]

Dear all,

I am wondering what causes the biorhythm of corals regarding when to extend
their tentacles and when not? Sometimes I see Fungia with extended polyps
during the night, sometimes during the day. Also due to vertical plankton
movement one would suggest feeding to be more efficient during night,
however some corals with Zooxanthellae extend their polyps during daytime
only.
Also the explanation that most of corals extend polyps during the night
because the photosynthesis is not working during day confuses me since
parts of the photosynthesis-machinery work also during night
(light-independent reaction). Or do Zooxanthellae not possess
dark-reaction?
Has somebody an idea?

Warm regards,

Barbara Gratzer MSc
~~~ Σ^^°> ~~~
Resident Marine biologist
Huvafen Fushi Resort
Republic of Maldives