Few coral species are able to free themselves after being completely buried in sand, but fungiid corals are an exception. They are able to inflate their polyps up to five times their normal size, and they can use mucus and ciliary action to free themselves. This time-lapse video shows the rhythmic pulses a fungiid coral uses to free itself from sedimentation.
Researchers led by Pim Bongaerts, Ph.D., from the University of Queensland, Australia, placed Fungia scutaria and Herpolitha limax corals from the Great Barrier Reef in aquariums and covered them in sand. The researchers photographed the corals every 10 seconds over 10 to 20 hours. In 10- to 20-minute intervals, corals inflated gradually (1 to 3 minutes), then inflated rapidly (10 to 15 seconds) and then deflated for 3 to 5 minutes. The corals repeated this process 15 to 25 times until they were freed from the sand.
Until now, no one knew how these corals were able to free themselves, as before time-lapse photography, no one was able to see their slow pulses and inflations.