Organisms are protozoa. Protozoa single-celled organisms

Organisms, whose body includes only one cell, belong to the simplest. They can have different shapes and all kinds of ways of movement. Everyone knows at least one name, which is the simplest living organism, but not everyone realizes that this is such a creature. So, what are they, and which species are most common? And what kind of creatures are they? Like the most complex and coelenterates, unicellular organisms deserve detailed study.

Sub-kingdom of the unicellular

Protozoa are the smallest creatures. Their bodies consist of a single cell, which has all the functions necessary for life. Thus, the simplest unicellular organisms have a metabolism, are able to show irritability, move and multiply. Some differ in the permanent shape of the body, while others constantly change it. The main component of the body is the nucleus, surrounded by the cytoplasm. There are several types of organoids. The first - obschelektoechnye. These include ribosomes, mitochondria, Galdzhi apparatus, and the like. The second - special. These include the digestive and contractile vacuoles. Almost all the simplest unicellular organisms can move without much difficulty. In this they are assisted by pseudopods, flagella or cilia. A distinctive feature of organisms is phagocytosis - the ability to capture solid particles and digest them. Some can also perform photosynthesis.

How are unicellular cells spread?

Protozoa can be found everywhere - in fresh water, soil or sea. A high degree of survival is provided by the ability to incase. This means that, under adverse conditions, the body falls into a resting phase, being covered with a dense protective shell. The creation of cyst contributes not only to survival, but also to spreading - so the organism can find itself in a more comfortable environment, where it will receive nutrition and the opportunity for reproduction. Organisms protozoa carry out the latter by dividing into two new cells. Some also have the ability to sexually reproduce, there are species combining both options.

Amoeba

It is worth mentioning the most common organisms. The protozoa are often associated with this species - with amoeba. They do not have a permanent shape of the body, and for the movement they use pseudopods. The same amoeba captures food - algae, bacteria or other protozoa. Having surrounded it with pseudopods, the body forms a digestive vacuole. From it, all the substances obtained fall into the cytoplasm, and the undigested is thrown out. The breathing of the amoeba is carried out by the whole body through diffusion. Excess water from the body is excreted by the contractile vacuole. The multiplication process occurs by dividing the nucleus, after which two cells are obtained from one cell. Amoeba are freshwater. There are protozoa in the human body and animals, in which case they can lead to a variety of diseases or worsen the general condition.

Euglena the Green

Another organism, common in fresh water bodies, also refers to the simplest. The euglenae have a green spindle-shaped body with a dense outer layer of the cytoplasm. The anterior end of the body ends with a long flagellum, through which the body moves. In the cytoplasm, there are several oval chromatophores in which chlorophyll is located. This means that in the light euglena feeds autotrophically - not all organisms know how. Protozoa are guided by the eye. If, however, euglena remains in the dark for a long time, chlorophyll will disappear and the organism will pass to the heterotrophic method of feeding with the absorption of organic substances from the water. Like the amoeba, these protozoa multiply by fission, and also breathe the whole body.

Wolvox

Among the unicellular colonial organisms are also found. Protozoa called volvox live just like this. They have a globular shape and gelatinous bodies, formed by individual members of the colony. Each wolfvox has two flagella. The coordinated movement of all cells ensures movement in space. Some of them are capable of reproduction. So there are affiliated colonies of cars. The same structure is distinguished and the simplest algae, known as chlamydomonads.

Infusoria-shoe

This is another common inhabitant of the fresh water body. The name of the infusoria is due to the shape of its own cell resembling a shoe. Organoids used for movement are called cilia. The body has a constant shape with a dense shell and two nuclei, small and large. The first is necessary for reproduction, and the second controls all life processes. As a food infusoria uses bacteria, algae and other unicellular organisms. The protozoa often create a digestive vacuole, in the shoes it is located at a certain place near the oral opening. To remove undigested residues, there is a powder, and the excretion is carried out with the contractile vacuole. Infusorians are characterized by asexual reproduction, but it can also be accompanied by the union of two individuals for the exchange of nuclear material. This process is called conjugation. Among all freshwater protozoan infusoria, the shoe is the most complex in its structure.

Unicellular in soil and sea water

In addition to the inhabitants of the fresh water body, it is worthwhile to list other types of protozoa. Thus, organisms of radiolarians and foraminifera are most often found in the sea. The dead bodies of the former form mineral deposits of opals and jasper. Foraminifers are distinguished by the presence of a shell of grains of sand or calcium, and after death they form lime or chalk. Both are part of the plankton. The soil is also inhabited by a variety of protozoa. They play an important role in the process of the formation of a new land. In addition, organisms can be parasites. They lead to the most dangerous diseases of people and animals. The most famous is the malarial plasmodium, which settles in the blood of a person. Dysentery amoeba can disrupt the operation of the large intestine. Trypanosomes carry a sleeping sickness.