Blue-green algae are represented by unicellular, filamentous and colonial forms. Their color depends on the level of pigment content (chlorophyll, phycoerythrin, phycocyan, carotene). Thus, they can be blue-green, olive-green or yellow-green, for example. They do not have a formalized nucleus and a chromatophore. Blue-green algae are represented by the following genera: nostok, oscillation, gleotrichia, anabena and others. All representatives lack the sexual process and flagellum stages.
The genus nostoc is nostock. These blue-green algae are common on aquatic plants in small ponds, moist soil, and are included in lichens. Their food is autotrophic, it consists in the processing of inorganic substances into organic. Reproduction occurs through spores or hormones (multicellular fragments). These blue-green algae are used for food by both animals (aquatic) and humans. In Siberia and in the European part of Russia, the Plum-like (edible) nest lives.
Representatives from this genus, as, however, from most other blue-green algae, form colonies. Colonies are accumulations of individual individuals in very large numbers. All this cluster is immersed in the mucous mass.
Individual algae cells are collected in long chains. Colorless, larger intermediate cells are also noted in the series of main cells. They perform a special task when reproducing. The cells in the nostock threads are divided in half all the time. Thus, the chains are lengthened, and from time to time, borderline (intermediate cells) are formed.
The mucus that surrounds the colony is of particular importance. So, when adverse external conditions occur, for example, the pond dries up, the mucus dries up, forming a kind of "case". At the same time, the cells that are inside it retain their viability for a long period, turning into resting spores, which are invulnerable neither to dry nor to cold. When favorable conditions occur, they continue their usual life activities.
Many of these blue-green algae can live on land. They form their colonies on the walls of houses, the bark of trees, in the body of other organisms (in freshwater hydra, for example).
The genus gloeotrichia is gleotrichia. These blue-green algae are quite common in stagnant water bodies, and sometimes they can also be found in brackish and flowing waters. Representatives from this genus inhabit aquatic plants, and also live on fallen leaves. Some species differ in their attached way of life, while others freely live in the water column. The nutrition of these algae is carried out phototrophically. Reproduction occurs with the help of hormones, spores can form. When these algae multiply in large numbers, water blooms.
Genus anabaena - Anabena. This genus includes a fairly large number of species. These algae are ubiquitous. They can be found in water bodies with a clay bottom, in lake and pond plankton, in soils, in rain puddles. The nutrition of these algae is phototrophic. Reproduction of representatives of this genus is carried out through hormones. These algae provoke flowering in water. It was established that representatives of the genus Anabena have the ability to fix atmospheric nitrogen. It is also known that certain species contain toxic compounds.
The genus oscillatoria is an oscillator. These algae are capable of forming a plaque on objects located at the bottom of water bodies. Oscillatorium films can often be seen on the water surface. These algae are inhabited by stagnant waters, moist walls, plankton, greenhouses and flower pots. Phototrophic nutrition, and reproduction through hormones. These algae are quite widespread, they can be found in different regions of Russia.