Red algae are ecologically significant as primary producers, providers of structural habitat for other marine organisms, and their important role in the primary establishment and maintenance of coral reefs.
Some red algae are economically important as providers of food and gels.
For this reason, extensive farming and natural harvest of red algae occurs in numerous areas of the world. Seaweed farmers tending a Kappaphycus line culture in the Philippines. Kappaphycus and other Gigartinales species are grown commercially for the extraction of carrageenan, a gel used in many food products. Starch is the photosynthetic reserve and is deposited free in the cytoplasm. Traditionally the red algae were divided into two Classes the Bangiophyceae and Florideophyceae.