(red algae) A division containing nonflagellate usually thalloid *algae
, most of which live in tropical seas, many epiphytic or parasitic on other algae. Red algae contain the phycobiliprotein pigments *phycocyanin
, which confer the characteristic red colour, although freshwater species are often grey-green. The Rhodophyta contains one class, the Rhodophyceae, divided into two subclasses, the Bangioideae (or Bangiophycidae) and the Florideae (or Florideophycidae). Sexual reproduction is less complex in the Bangioideae and this group also lacks pit connections between the cells, which are a prominent feature of the Florideae. Certain members of the Florideae secrete a calcareous covering and play a part in the formation of coral reefs.