what is algae class 7

Algae are chlorophyll-bearing, simple, thalloid, autotrophic, and largely aquatic (both fresh water and marine) organisms. They are a large and incredibly diverse group of eukaryotic, photosynthetic lifeforms that do not share a common ancestor and hence, are not related to each other (polyphyletic) . Algae are not closely related in an evolutionary sense, and the phylogeny of the group remains to be delineated. They are found all over the world, and there are about 27,000 different species, or types, of algae. Algae can be green, blue, red, or brown, and they vary greatly in size. Some species are so small that they can only be seen through a microscope, while others, such as kelp, can reach 200 feet (60 meters) in length. Algae differ from plants in several ways. They do not have stems or leaves, and their roots are different from plant roots. Algae also do not produce flowers or seeds, as plants do. Like plants, however, algae make their own food through a process called photosynthesis. Photosynthesis also releases oxygen into the air. The green, slimy patches that grow in moist areas or stagnant water are called algae.