Algae are the oldest plants on Earth. Algae belong to lower plants, they have no roots, no stems, no leaves. Among algae there are unicellular and multicellular plants. Algae reproduce by simple cell division or spores.
Green algae live in salt and fresh water, on land, on the surface of trees, stones or buildings, in damp, shaded places. The simplest green algae are unicellular.
During the “blooming” of small puddles or reservoirs, the water has an emerald hue. In a drop of such water under a microscope, many different unicellular green algae are clearly visible. The most common unicellular algae Chlamydomonas (translated from Greek – “the simplest organism covered with clothes” – a shell).
Chlamydomonas is a unicellular green pear-shaped alga. It moves in water with the help of two flagella located at the anterior, narrower end of the cell. Outside, chlamydomonas is covered with a transparent membrane, under which are located the cytoplasm with a nucleus, a red “eye” (a light-sensitive body of red color), a large vacuole filled with cell juice, and two small pulsating vacuoles. Chlorophyll, contained in the chromatophore, gives a green color to the entire cell.
Chlorella is another unicellular green alga that is widespread in fresh water and wet soils. Its small globular cells are visible only with a microscope. Outside, the chlorella cell is covered with a membrane, under which there is a cytoplasm with a nucleus, and in the cytoplasm there is a green chromatophore.