This is typical. Once it eats, it has enough solid food to sustain it for awhile. When it feels the need for additional nourishment, it will extend it's tentacles so more light can get to the zooxanthellae algae that lives inside it. Similar to other corals, anemones have a symbiotic relationship with zooxanthellae algae, and through the process of photosynthesis, the algae provides the nem with sugar. In return, the nem provides the algae safe haven...