What are Red Algae? Red algae belong to the group Rhodophyta, named for the red pigment (phycoerythrin) these protists use to photosynthesize. Some members of this group are unicellular, others multicellular, and still others multinucleate (many nuclei in one cell). Some rhodophytes are important sources of food, such as nori, which is cultivated in Asia. Some red algae, called coralline algae, build shells of calcium carbonate, and contribute to the construction of coral reefs. The fossil record of unicellular red algae extends back to the Precambrian, while the coralline algae first appear in the Cambrian. Both groups are still around today.
First known fossil occurrence: Precambrian.
Last known fossil occurrence: Quaternary. This group has living relatives.
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