Red Algae

Red algae, or Rhodophyta, make up one of the oldest and largest phyla of eukaryotic algae, with over 7,000 recognized species across more than 900 genera. Most species belong to the class Florideophyceae and are multicellular marine organisms, including many familiar seaweeds, though about five percent of species live in freshwater, mostly in warmer regions. Red algae lack flagella and centrioles and have chloroplasts containing phycobiliproteins, which give them their characteristic red color, though they can also appear green, pink, brown or nearly black depending on depth and conditions.