what kinds of coral are in the great barrier reef
Great Barrier Reef There are at least 330 species of ascidians on the reef system with the diameter of 1–10 cm (0.4–4 in). Between 300–500 species of bryozoans live on the reef.[40] Four hundred coral species, both hard corals and soft corals inhabit the reef.[32] The majority of these spawn gametes, breeding in mass spawning events that are triggered by the rising sea temperatures of spring and summer, the lunar cycle, and the diurnal cycle. Reefs in the inner Great Barrier Reef spawn during the week after the full moon in October, while the outer reefs spawn in November and December.[44] Its common soft corals belong to 36 genera.[45] Five hundred species of marine algae or seaweed live on the reef,[32] including thirteen species of genus Halimeda, which deposit calcareous mounds up to 100 metres (110 yd) wide, creating mini-ecosystems on their surface which have been compared to rainforest cover.[20]:185
Coral Although corals first appeared in the Cambrian period,[28] some 542Â million years ago, fossils are extremely rare until the Ordovician period, 100 million years later, when rugose and tabulate corals became widespread. Paleozoic corals often contained numerous endobiotic symbionts.[29][30]