What is the Difference Between Green and Brown Algae?

Green and brown algae are two groups of algae that together make up most of the algae in the world, though they are quite different. Along with red algae, both brown algae and green algae are sometimes referred to using the colloquial term "seaweeds." Though both are eukaryotic (complex-celled) multicellular organisms, they belong to different kingdoms, with green algae belonging to Plantae and brown algae to Chromalveolata. Plantae and Chromalveolata are two of the six major eukaryote divisions, the others being Fungi, Animalia, Amoebozoa, Rhizaria, and Excavata. Both groups of algae are mostly marine, but green algae is better adapted to fresh water than brown algae. Brown algae is most familiar to us as kelp, marine algae with a very high growth rate, and Sargassum, a surface-floating variety of brown algae that makes up the Sargasso Sea and provides a unique habitat for eels and other animals. Though kelp and Sargassum are the best known brown algae, there are over 1,500 species ...  more