Cycloseris distorta

Cycloseris distorta is a free-living, solitary disc coral from the family Fungiidae. It lives on soft sediment in shallow tropical and subtropical waters of the Indo-Pacific. The coral can absorb water to inflate itself to several times its normal size, and its large polyp has an irregular shape with a central mouth and wedge-shaped segments radiating outward.

The stony cup, or corallite, contains numerous beaded partitions of varying heights. When its tentacles are extended for feeding, the coral appears fuzzy. Its coloration ranges from cream to pale fawn, sometimes mottled.

This species was first described in 1842 by French naturalist Jean-Louis Hardouin Michelin de Choisy, who named it Fungia distorta. It was later moved to the genus Diaseris as Diaseris distorta, but molecular research in 2011 led to Diaseris being absorbed into the genus Cycloseris.

Cycloseris distorta is found across the Indian and Pacific Oceans, from the east coast of Africa and Madagascar to Sri Lanka, Malaysia, Indonesia, northern and eastern Australia, and the Galapagos Islands. It typically occurs at depths of 25 meters or less, though it can be found down to about 80 meters. In the Galapagos, a single location hosts a dense population estimated at several hundred thousand individuals, sometimes piled on top of one another. On a nearby island, large numbers of dead skeletons exist but no living corals.

Individual corals are either male or female. They reproduce through broadcast spawning four to eight times per year, and asexual reproduction by fission is also important. Fragmentation can occur from physical forces like storms, but the coral can also deliberately break itself apart through autotomy, selectively weakening parts of its skeleton.