Sea anemone with zooxanthellae: simultaneous contraction and expansion in response to changing light intensity.
Under increasing intensity of light, the normal tentacles of Lebrunea contract whereas the pseudotentacles expand; in decreasing light the reverse is true. This behavior may be correlated with greater numbers of zooxanthellae in the pseudotentacles. Simultaneous but opposite response of parts suggests adaptations toward photosynthesis by day and predation by night.
Gladfelter
W B
WB