Florideophyceae

Florideophyceae is a class of red algae (Rhodophyta) and represents the majority of the group's biodiversity. Members are predominantly marine and occupy a wide range of habitats, from shallow intertidal zones to deep waters. They exhibit diverse thallus forms, from delicate filaments to leathery sheets and crusts, including calcified crusts formed by coralline algae.

A defining feature of Florideophyceae is their complex life history. Most species display a triphasic life cycle that includes a haploid gametophyte, a diploid carposporophyte that develops on the female gametophyte, and a diploid tetrasporophyte that produces tetraspores. The carposporophyte is typically embedded in the maternal thallus. Reproductive structures such as carpogonia, trichogynes, and tetrasporangia are characteristic of many members.

Ecology and distribution: Florideophyceae are mainly marine and contribute significantly to coastal ecosystems. Freshwater representatives exist in smaller groups, such as Batrachospermales. Crustose forms, including coralline algae, play important roles in substrate stabilization and reef-building in some habitats.

Economic importance: Several Florideophyceae produce hydrocolloids used commercially. Agar is derived from genera such as Gelidium and Gracilaria, while carrageenan is sourced from various Florideophyceae, notably among the Gigartinales and related taxa.

Taxonomy: Within Rhodophyta, Florideophyceae is one of the major classes alongside Bangiophyceae. It comprises numerous orders, including Ceramiales, Corallinales, Gigartinales, Rhodymeniales, and Batrachospermales, reflecting substantial morphological and ecological diversity.