Difference Between Red and Green Algae

Red vs Green Algae

Algae are a group of organisms showing high diversity among them. They are grouped into one, based on the fact that they also can perform photosynthesis like plants do. These organisms mostly reside in aquatic environments. In the classification, we find 3 main classes of algae; namely, Red algae, Green algae, and Brown algae. All the algae are eukaryotes having double membrane bound organelles and show complex cellular organization when compared to bacteria. 

Red Algae 

Red algae belong to phylum (group) Rhodophyta. They are “Red” because they seem red in color mainly due to the presence of pigments phycoerythrin, a reddish pigment. Some red algae having low phycoerythrin content may also appear in greenish, bluish colors. These multicellular organisms have the ability to secrete calcium carbonate e.g. sea weed. Therefore, red algae are very important in making of tropical coral reefs. Most of the red algae are found in sea water while some are also found in fresh waters. Red algae can photosynthesize. They appear in red because they absorb counter color blue, a high energy wavelength. Since the blue color radiation can penetrate deeper in the ocean, red algae can live and photosynthesize in deep oceans, unlike many other algae. Red algae are a popular food in many parts of the world due to the high vitamin and protein content. In Japan, it is used to make nori. Red algae are also used to make agar. 

Green Algae 

Green algae are the most diverse group of algae living in many forms and habitats. They appear green in color because they contain chlorophyll pigments, similar to plants. But in unfavorable environmental conditions some also appear in red color. Algae are considered to be the closest to plants in the history of evolution. Green algae can be unicellular or multicellular and can be found in bag like colonies, spherical colonies, flagellated and motile forms, long filament and thread like forms. Most of the green algae are found in fresh water, humid soil, attached to rocks and tree barks, but some are found in marine environments as well, e.g. Ulva. Green algae can also photosynthesize. However, they absorb red light, a low energy wavelength than the red algae. Because red light cannot penetrate much deeper in the ocean, these algae are found in low tide areas, attached to rocks. Some green algae show symbiotic associations with fungi and lichens. 

What is the difference between Red algae and Green Algae? 

• Red algae generally appear in red color while green algae generally appear in green color.

• Red algae are mainly found in the marine environment while green algae are found in many environments like fresh water, snow, attached to tree barks and in symbiosis with fungi and lichens.

• Red algae can live in the deep sea because they absorb high energy blue light and green algae are restricted to low tide areas because they absorb red light, which has lower energy.

• Red algae are used as a food source while green algae are considered as potential bio-fuels.