Infusoria slippers belong to the class of the most highly organized protozoan microorganisms. They live in standing shallow reservoirs. If we compare them with other groups of protozoa, then ciliates have a more complex structure.
Features of microorganisms
The class of ciliates-shoes is considered one of the most highly organized. They are quite large: their size can reach 0.5 mm. They got the name due to their shape, in appearance resembling the sole of a shoe.
Infusoria slippers are always in motion. At the same time, they swim with a blunt end forward. The speed of their movement is great - about 2.5 mm per second. This means that they cover a distance of 5-10 times the length of their own body. Moreover, the trajectory of their movement is very specific: they not only move directly, but also perform rotational movements along the longitudinal axis to the right.
You can breed these microorganisms in small aquariums. To do this, it is enough to fill the usual meadow hay with water from the pond. In such a tincture, a mass of simple microorganisms is formed. As a rule, an infusoria shoe can also be detected under a microscope. Photos of this microorganism provide an opportunity to understand why he was given such a name.
Traffic provision
The body of these microorganisms is elongated and looks like the sole of a shoe. The front end is narrow, the widest part is the rear third. The body is evenly covered with cilia, which are arranged in rows. On the body of these microorganisms there are about 10 thousand. All of them work synchronously - make wave-like movements. Ciliates move thanks to these harmonious movements.
Each cilia at room temperature makes about 30 paddle-like movements per second. An oscillating wave starts from the front of the body and goes back. At the same time, 2-3 waves of contractions are carried out along the body of this microorganism. All cilia are a single functional whole - their actions are coordinated among themselves, as biology has long confirmed. An infusoria shoe can move in different directions and at different speeds. She can respond to changes in the external environment, changing the direction of movement.
External features
Biologists conditionally call one of the sides of the trunk of ciliates a peritoneum. On this part, a deep gutter extends inward. It is a near-mouth hole and is called a feather. At its back is the mouth and throat. On the walls of the peristome, cilia are longer. This is a special hunting device that drives food into the mouth opening of the ciliates.
The outer cover of a microorganism is a cell membrane, which is a thin elastic membrane. It is she who provides a constant body shape, which differs from other groups of the simplest ciliates-shoe. Grade 7 in schools is just studying these microorganisms. It was at this time that children learn that each cilium has a rather complex structure.
Structure
A detailed examination of the ciliates-shoes can see that her body is clearly divided into two layers. The outer cover is lighter. It is called ectoplasm. The inner layer is darker, it is distinguished by a granular structure. They call it endoplasm. The surface layer of the ectoplasm is a shell that is responsible for the fact that there is always one form of ciliates-slipper. A photo taken under an electron microscope allows you to see a dense shell, which is called a pellicle.
In the outer layer between the cilia are perpendicular sticks. They are called trichocysts and perform a protective function. With irritation, trichocysts sharply with force are thrown out, forming thin long strings. With their help, a predator is struck, trying to attack the shoe. In place of the used trichocysts, new ones grow.
Power Features
The class of ciliates-shoes is considered one of the most gluttonous. The process of feeding them stops only during reproduction. The mouth opening of these microorganisms is always open. Therefore, the flow of food particles that enter the mouth is virtually uninterrupted.
During the movement of the cilia create a constant flow of water around the body of the ciliates. With it, food enters through the mouth opening into the throat and accumulates at its bottom. Together with a small amount of water, food particles leave the bottom of the pharynx and pass into the cytoplasm. In this case, a digestive vacuole is formed. Separating from the pharynx, for an hour she makes a certain path through the body of the ciliates.
First, the vacuole moves toward the back of the body. After that, having described a small arc, it begins to move to the front edge. Then the vacuole begins to move around the periphery of the body.
Processing of food in the body of these microorganisms in a certain place is completed. It is there that undigested residues go outside. This distinguishes between such microorganisms as the ciliates, slipper, green euglena, amoeba. The first of them has a precisely defined place in which the selection process takes place. This is the so-called abdominal wall. But, for example, in an amoeba, the process of defecation can take place anywhere.
Food processing
During movement, digestive enzymes constantly enter the vacuole, and the digested food is already absorbed into the cytoplasm. Several stages in the digestion process are distinguished by biology. After the formation of a special vacuole, the ciliates-shoe begins to produce special enzymes.
If in the first moments the contents of the digestive organ does not differ from the environment, then after a while it changes. The medium in the vacuole becomes acidic - the digestion process begins. After that, the picture changes. Inside vacuoles, the medium becomes slightly alkaline. These conditions are necessary to continue digestion. The ratio of the duration of the acidic and alkaline phases can vary depending on the nature of the food. But as a rule, the first part is no more than ¼ of the entire period of digestion of food. The process of absorption of food stops at the time when the breeding of the ciliates-slippers occurs.
Excretory system
In the body of ciliates, shoes are not only digestive vacuoles. There are also special excretory organs. They are called
contractile vacuoles. In all ciliates, two such excretory organs can be found: one is in the first, and the second in the last third of the body. Each of them has a special structure.
Vacuoles consist of a central reservoir and suitable supply channels. The cycle of their work begins with filling the fluid with radially located channels. Their contents are poured into the tank, and from it through a special time it comes out.
At this time, the channels again begin to fill with liquid. In this case, the front and rear vacuoles are reduced in turn. The intensity of their work depends on environmental conditions. At room temperature, this cycle takes 10-15 seconds.
Functional Features
Like other simple microorganisms, ciliates have a
cell nucleus. But in structure it is noticeably different. The nuclear apparatus is notable for the fact that ciliates have two different types of nuclei. This is one of their main differences from other microorganisms. In the center of the body (in the area of the peristome) there is a large nucleus. It is usually ovoid. It is also called macronucleus. Close next to it is another core, which is several times smaller than its size. It is called micronucleus. But the difference is not only in size, their structure also varies markedly.
In the macronucleus, the number of chromosomes is several hundred times greater than in the micronucleus. Therefore, the amount of chromosomal substance (chromatin) in them varies significantly. By the way, when studying the reproduction of the ciliates, you can find out that both nuclei are involved in this process.
To obtain offspring, just one microorganism is enough. But under certain conditions, the conjugation process begins. This is the name for the sexual reproduction of ciliates. It is worth noting that this process is quite lengthy.
Asexual reproduction
Empirically, the method of propagation of the ciliates was studied. When transplanting one individual into a separate aquarium in a day, 2 or 4 microorganisms can already be found there. The period of active swimming and nutrition ends with the fact that the body of the ciliates is extended in length. Exactly in the middle there is a deepening constriction, which serves as a place for the separation of one microorganism into two. The whole process of division under favorable conditions lasts about an hour.
Asexual reproduction of the ciliates takes place as follows: even before the constriction appears on the body, the nuclear apparatus begins to double. Micronuclei are the first to divide, then the turn reaches the macronuclei. At the same time, the process of fission of the small nucleus resembles mitosis, and the large - amitosis.
During this process, there is a noticeable deep restructuring of the body. Two pharynx, two oral openings and two peristomes are formed. The basal nuclei of the cilia covering the body are also divided. Thanks to this, the bodies of the educated individuals are densely covered by them.
Sexual reproduction
In some cases, the conjugation process can be observed. This is the sexual reproduction of ciliates. It occurs as follows: two microorganisms tightly come together, applying to each other with abdominal walls. As such, they continue to swim for about 12 hours. Then they disperse. Moreover, in the body of ciliates, the large nucleus disintegrates and gradually dissolves in the cytoplasm. Micronuclei at first divide, but part of the nuclei formed in this process decays almost immediately. In each ciliator involved in the process, 2 cores remain. One of them remains in place, and the other moves into a partner and merges with the core that the ciliates-shoe already had.
The form of reproduction, passing in this way, provides cross fertilization. The genital nuclei of cells merge . As a result, a special structure called syncaryon is formed in the ciliates. This is a complex core that divides one or more times and turns into macronuclei. After restoration of the normal nuclear apparatus of ciliates, the process of asexual reproduction continues.
It is important to understand that this method of propagation of ciliates does not lead to an increase in the population, but to an increase in hereditary diversity.