Euglena green is a unicellular animal found in fresh stagnant reservoirs, swamps, ditches, puddles. The color of this organism is due to the content of a large number of chloroplasts in the cytoplasm. Therefore, it seems that the water "blooms" when euglena green is overly diluted in it.
Its structure is a bit more complicated when compared with an amoeba. Both have a protoplasm and a nucleus. However, green euglena is still covered on the outside with a layer of pellicle - an elastic membrane. The body has a shape resembling a spindle, blunt from one end and elongated from the other. A small flagellum comes out of the groove at the front edge. There is also a bright red “eye” that responds to light and thereby helps the cell to choose the direction of movement. Next to it is a vacuole. Thanks to the compacted outer shell, the shape of the animal does not change significantly, it can only slightly, at certain boundaries, contract and straighten. This euglena green structure also determines the way of moving. Making rotational movements with a flagellum , this microscopic creature swims quite quickly. There are varieties that make undulating vibrations with the body and thus swim. Why this happens is not yet clear. Biologists have two assumptions about this. On the one hand, there may be a connection between the euglena organelles and protein threads that are under the pellicle and can contract. And on the other hand, this type of movement can be caused by mucus secreted by the cell.
Green can eat euglena both as an animal and as a plant. The way she chooses depends on the lighting. Its protoplasm contains more than twenty oval bodies - a chromatophore. They, as already mentioned, and stain the cell in green. During the day, using chlorophyll contained in chromatophores, euglena green is able to participate in photosynthesis, assimilating the carbon it needs in the same way as plants from carbon dioxide. At the same time , a nutrient is formed from inorganic substances in her body that resembles starch and is deposited in the form of grains in the cytoplasm. At night, this cage can eat just like an animal. With the help of vacuoles, it is capable of immediately processing organic substances, which in water bodies are plenty in the already dissolved form. So does the amoeba. And the more neglected the reservoir, the more of these substances. If euglena green has been in the dark for a long time, chlorophyll from the chromatophores disappears. Accordingly, the color of the cell disappears, it completely discolors.
There are species that are generally unusual for photosynthesis; they can eat exclusively as animals. They even develop a peculiar oral apparatus for swallowing microscopic particles of food.
The ability of this organism to choose a nutritional method once again indicates to scientists that animals and plants have the same origin.
Green euglena propagates by longitudinal division of the cell itself: after protoplasm, it splits into two halves and a nucleus. Each appeared individual grows a new flagellum. Under favorable conditions, euglena green is so diluted that water also becomes the corresponding color. There are species of these unicellular organisms that, evolving, have remarkably adapted to live even in the cold. As a result of this adaptation, during the time of their mass reproduction, snow turns not only green, but also red, yellow, and even blue.
There are also euglena cells whose cells are saturated with carotene. They paint water bodies in red or brown. When rivers, puddles, swamps, etc. dry up or freeze, green euglena loses its flagellum, rounds, becomes covered with a thick shell - for a while it transforms into a cyst. In this form, it can wait for favorable conditions in the same place or be transported along with dust.