Fact Friday
The coral in the photograph looks more like a soft coral than a hard coral. Corals in the genus Plerogyra, termed bubble or grape corals, expand their water-filled bubbles or vesicles during the day in order to maximize the exposure of their symbiotic algae (zooxanthellae) to sunlight. At night, the vesicles retract so that their tentacles can expand to feed on small organisms. Watch this video to see the vesicles expanding: https://youtu.be/r5I6TM3nnbU
Photo Credit: Annelise Hagan
