Crustose Coralline Algae
Rhodophyta, Corallinaceae/Sporolithaceae
Hawaiian name: none
Characteristic feature: Pink rock.
Description: Encompassing a broad range of genera. Calcareous, nonarticulated (no uncalcified portions of thallus) red algae that form crusts over coral or limestone reef. Some species are nodulated, branched or form thin plates. Colors range from pink, dull red, blue-violet, maroon, to green. Reproductive organs are sunken into cavities (conceptacles).
Habitat: Reef flats; intertidal to deep subtidal.
Hawaiian distribution: All main Hawaiian Islands, including North West Hawaiian Islands.
Other: Major reef-buiding organism in Hawai‘i, consolidating and cementing reef material. Encrusting Peysonnelia species can often be confused with crustose coralline algae; they can be distinguished by the red coloration, and calcification only on the lower surface of the thallus. Common genera include Hydrolithon, Neogoniolithon, Lithophyllum, Mesophyllum, and Sporolithon.