Rödalg

Rödalg, also known as red algae, refers to a large and diverse group of eukaryotic organisms belonging to the division Rhodophyta. These organisms are predominantly multicellular, though some are unicellular or colonial. Red algae are characterized by the presence of phycobilins, accessory photosynthetic pigments that give them their distinctive reddish hue, although some species can appear green, purple, or even black depending on the concentration and type of these pigments, as well as the depth at which they grow.

These algae are found in a wide range of aquatic environments, from shallow coastal waters to the deep sea, and also in freshwater habitats, although they are less common there. They play crucial roles in marine ecosystems, contributing to primary productivity, providing habitat for other organisms, and participating in the formation of coral reefs through the calcification process in some species like coralline algae.

Red algae exhibit a variety of forms, including filamentous, branched, sheet-like, and complex thalloid structures. Their life cycles can be complex, often involving alternation of generations. Economically, red algae are important for various purposes. Certain species are cultivated and harvested for food, such as nori used in sushi. They are also a significant source of agar and carrageenan, hydrocolloids widely used as gelling agents, thickeners, and stabilizers in the food industry, as well as in pharmaceuticals and biotechnology.