Chlorophyta: The Green Algae

Chlorophyta are a division of green algae, which are either free-floating or anchored on the shore rocks or in large aggregations on stagnant water, such as ponds. The Chlorophyta has 450 genera and 7,000 species under it. This diversity is comparatively larger than other types of algae. Chlorophyta, although called the green algae, are found in diverse colors like yellow, purple, red, orange and even black. Carotenoids are the color pigments which give color to Chlorophyta. They reproduce by the process of oogamy or isogamy.

Chlorophyta are similar to terrestrial plants in many ways. They contain chlorophyll a, chlorophyll b, carotene a, carotene b and xanthophylls, which help in photosynthesis. The cell wall contains cellulose and pectins. A few species, like Halimeda, also contain calcium carbonate in their walls.

Chlorophyta has more freshwater species than marine species. The freshwater species are smaller in size. A few species of Chlorophyta, commonly known as 'snow algae', can grow in snow and glaciers. They have high concentration of carotenoid deposit in their cells, which gives them a red hue. They are found in the Rocky Mountains, the Cascades, the Arctic and the Antarctica.

Chlorophyta are the autotrophic organisms. A few species have formed a symbiotic relationship with lichens, hydras and mollusks. They are eukaryotes with all normal cell contents like nucleus, golgi bodies, vacuoles, pyrenoid, starch, chloroplasts, flagella and cell wall.

Some species of Chlorophyta form cell plates during mitosis. They also have the typical double boundary membrane like plants. The common shape of chloroplasts are cup, filament, star, reticulate and banded. A few also have discoid shape similar to the terrestrial plants. For example, Spirogyra has spiral chloroplasts. Band-shaped chloroplasts are found in Ulothrix, Zynema contains star-shaped chloroplasts. Cup-shaped chloroplasts are found in Chamydomonas. Cladosphora has many oval chloroplasts and Mougeotia contains a flat chloroplast.

Many species of Chlorophyta contain pyrenoids, which are used in the starch synthesis and its deposition. Starch, the major storage product of Chlorophyta, is stored in the stroma of chloroplasts. They have a wide range of morphological diversity. There are unicellular like Golenkinia, filamentous like Microthamnion, siphonous, multicellular, colonial like Volvox, parenchymatous like Coleochaete, motile and non-motile types. They have various sizes, which can range from a few microns to meters. The largest known Chlorophyta is Ventricaria ventricosa. This species has one cell that can be several centimeters in diameter.

Chlorophyta are an important source of food to marine animals like planktons. As they carry out photosynthesis, they play a significant role in contributing to the world's oxygen supply. The pigment beta carotene is used as a food coloring agent. It is also thought to contain anti-cancer properties. Researcher in January 2009, found that algae can play an important role in reducing the global warming. It was explained that as sea ice melts, iron gets introduced to the oceans. This helps in the growth of algae, which in turn, absorb the carbon dioxide.

On the other hand, Chlorophyta tends to impart an unpleasant taste and odor in drinking water. They also clog the filtration equipment. If the algal population increases in the water source, they form scums. This scum can decrease the oxygen supply for other marine organisms.

Although, Chlorophyta look like simple organisms, there's more to these organisms than that meets the eye.