Dinoflagelletes produce light when the deformation of the cell by minute forces triggers its luminescence. When the cell is disturbed by a predator, it will give a light flash lasting 0.1 to 0.5 seconds. The flash is meant to attract a secondary predator that will be more likely to attack the predator that is trying to consume the dinoflagellate. The light flash also makes the predator jump and worry about other predators attacking it, making the predator less likely to prey on the dinoflagellate. In most dinoflagellates, bioluminescence is controlled by an internal biological rhythm.
Dinoflagellates are on a circadian rhythm.
Towards the end of daylight, luminous chemicals are packaged in vesicles called scintillons. The scintillons then migrate to the cytoplasm from the area around the nucleus. It is not currently known how the scintillons are moved to the cytoplasm. At night, light is triggered by mechanical stimulation. When action potential generates in the vacuole, the action potential propagates throughout the rest of the cell.