Movie 6.

Coral larvae contract the body in response to light dimming. Two examples of coral larvae are shown from cohorts from consecutive spawning years. The larvae are tethered on a suction micropipette as the light stimulus is turned on and off, twice. Video playback is 10x. Note the muscle contraction events in dark periods, gradually rounding the body shape. An elongated shape is resumed in bright light periods via muscle relaxation.