Algae is a generic name given to a few groups of protists. They are a hugely diverse group of organisms and are found in a number of places along the evolutionary tree. Traditionally, all algae are believed to have evolved from cyanobacteria, i.e. the blue-green algae, or the fusion of a cyanobacterium with another larger cell. This fusion is believed to have occurred through a number of different ways over time which has led to the separation between algal branches on the evolutionary tree.
One definition of algae is that they contain chlorophyll a for photosynthesis but lack true roots, stems and leaves. They generally have simple cells and lack many of the organelles found in more advanced organisms, such as plants and animals.
They can be found in almost all environments on Earth and are the main primary producers in most aquatic environments where they are the basis of the food chain. The large proportion of algal species exist as microscopic single-celled organisms and are only noticed during algal blooms, although some species of seaweeds, known as macroalgae, can grow as tall as 65m. Algae include almost all seaweeds and phytoplankton, they form what is known as a symbiotic relationship with fungi to form lichens and do the same with corals to help build coral reefs in nutrient poor tropical water.[five_columns][service title=”Seaweed” icon=”globe”]Seaweed (or macroalgae) are a diverse group of mostly photosynthetic algae found in marine and freshwater environments. They have evolved in three different divisions: red seaweeds, brown seaweeds and green seaweeds.[/service][/five_columns] [five_columns][service title=”Diatoms” icon=”pacman”]Diatoms are microscopic algae and are unique due to their silicon-based cell walls. Of the 10,000 species, most are found mostly in marine and freshwater habitats and most species are photosynthetic.[/service][/five_columns]