Order Shell amoeba: description, structure, meaning, interesting facts

Shell amoebae, whose structure we consider in this article, have a number of features that significantly distinguish them from other representatives of unicellular animals. What is special about these amazing organisms?

Shell amoebae: distinctive features

Let's start with the classification of these animals. They are representatives of the sub-kingdom of the Unicellular, belonging to the Sarkodov detachment. Their body has a non-permanent shape, since it lacks a compacted near-wall layer. These cells are moved by means of pseudopods - temporal protrusions of the cytoplasm. The cell has a typical amoeba structure. It consists of a membrane, cytoplasm and organelles: nucleus, mitochondria, contractile and digestive vacuoles.

Features of the amoeba shell

Most of the body of this type of amoeba is in the sink. This structure is 50 to 150 μm in size and has a round or pear-shaped shape. Through the hole, which is called the mouth, the shell amoebas release the pseudopods outward. This is necessary for their movement. Shells can be formed by pseudo-chitin or organic matter.

In some, they consist of a substance that is in the environment. The process of formation of such shells occurs in several stages. First, the amoeba with the help of pseudopods begins to draw sand particles, fragments of shells of diatoms or other solid particles inside the cell. Then they are glued together with cytoplasm and released to the outside. Anatomically, the shell of shell amoebae can be divided into three parts. At the top in its cytoplasm are the nucleus and various kinds of inclusions - reserve nutrients. In the middle there are digestive and contractile vacuoles. And closer to the mouth of the cytoplasm is deprived both organelles and inclusions. Out of it are formed pseudopods.

Interrelation of structure and environment

Shell amoebae are widespread in fresh and salt water bodies, mud, well-moistened areas of soil, plant surface, marsh mosses. Their habitat affects certain features of the structure. For example, shell amoeba diffluva, which is a typical resident of fresh water bodies, has one mouth. In the few inhabitants of the seas, the shell is thoroughly penetrated with calcareous needles, so the pseudopods come out of a large number of holes.

Interesting research

Among the freshwater inhabitants there are a number of amoebae, which prefer to live only in highly polluted water. Other species die in such conditions. This is also proved by numerous laboratory experiments. Imagine that several types of shell amoebas were placed in moist soil. Further, this medium is artificially contaminated with oil. After a few days, the species diversity will decrease significantly. Some shell amoebae begin to turn black and change shape.

Physiology of amoebae

Shell amoebae are characterized by a number of features of the course of physiological processes. Reproduction of their cells is carried out by dividing in two, like other representatives of the sub-kingdom. However, due to the presence of the shell, there are a number of differences. So, first around the protruding part of the amoeba begins to form a new shell, and only then the division takes place. Initially, the daughter organisms still remain connected with each other by the cytoplasmic bridge. Then it is rewritten. As a result, the offspring are separated and move on to independent existence.

For some species, the method of cell multiplication is multiple division. The process of crushing takes place inside the shell. As a result, naked cells appear outward. They form a shell independently in the process of their vital activity.

Move the amoebae using the pseudopods. These unstable protrusions of the cytoplasm are also called pseudopodia. To move the amoeba pulls forward the pseudopod, which is held by the support, and then pulls the entire body to it. In nature, this type of movement is also characteristic for blood leukocytes and phagocytic cells, therefore it is called "amoeboid".

Feeding of amoebae occurs by capturing its particles with pseudopodia and subsequent digestion in specialized vacuoles. Gas exchange occurs through the surface apparatus of the cell. Regulation of osmotic pressure is carried out by contractile vacuoles, by means of which excess water is removed with salts dissolved in it.

With the onset of unfavorable conditions, shell amoebas fall into the state of cyst. Their shell thickens, and the intensity of metabolic processes is significantly reduced. When conditions change, cells move to normal functioning.

Shell amoebae: meaning in nature

These are important organisms in the ecosystem. Shell amoebae, in conjunction with other single-celled organisms, are an integral part of it. These organisms are a link in the food chain, an indicator of the degree of purity of fresh water. The importance of shell amoebae in the process of formation of rocks is invaluable. Freshwater and sea protozoa as a result of their vital activity created limestone, chalk and other sedimentary rocks.

In nature, also known as a sarcod, which is very dangerous for humans. The killer ameba literally feeds on the human brain. At the moment, 23 cases of human infection with this organism have been recorded. This species of unicellular is an inhabitant of fresh water bodies. Inside a person, it penetrates through the nasal cavity, continuing its journey in the canal of the olfactory nerve to the brain. As it moves, it destroys all the tissues that serve as a barrier to it. The person at the same time first experiences severe headaches, chills, caused by an increase in body temperature. Then begins such signs of brain destruction as fever and hallucinations, which inevitably leads to death.

So, the representatives of the detachment Shell amoeba are unicellular animals belonging to the Sarcod class. Their cells have an irregular shape of the body and the pseudopod as movement organelles. On the outside of the membrane, this kind of amoeba itself forms a shell.