Algae include simple microscopic planktonic organisms and large macroalgae, or seaweeds. Identifying seaweeds can sometimes be difficult, as they vary in shape and colour, and because different phases of the life cycles of some species differ substantially. Texture and habitat are useful characteristics for identification.
Seaweeds are separated into three divisions : the green algae (Chlorophyta), the brown algae (Phaeophyta) and the red algae (Rhodophyta).
Seaweeds are of considerable economic importance. For example, kelps, Gelidium and Gracilaria species are already commercially harvested, but many other species are potential targets for commercial exploitation.




