red algae

Red algae, also known as Rhodophyta, are a diverse group of mostly marine, photosynthetic organisms characterized by their reddish color, which comes from pigments called phycoerythrin. They can range from small filaments to large, complex seaweeds like nori, used in sushi. Red algae play vital roles in aquatic ecosystems, providing habitat and food for marine life, and are important economically for producing products like agar and carrageenan, which are used as thickening agents in food and cosmetics. They are among the oldest groups of eukaryotic algae, contributing significantly to oceanic bio-productivity.