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
Coralline algae Coralline algae are red algae in the order Corallinales. They are characterized by a thallus that is hard because of calcareous deposits contained within the cell walls. The colors of these algae are most typically pink, or some other shade of red, but other species can be purple, yellow, blue, white or gray-green. Coralline algae play an important role in the ecology of coral reefs. Sea urchins, parrot fish, and limpets and chitons (both mollusks) feed on coralline algae. In the temperate Mediterranean sea, coralline algae are the main builders of a typical algal reef, the CoralligÃ¨ne ("coralligenous").[5] Many are typically encrusting and rock-like, found in marine waters all over the world. Only one species lives in freshwater.[6] Unattached specimens (maerl, rhodoliths) may form relatively smooth compact balls to warty or fruticose thalli.