Appearance of the ciliate slipper. What is the ciliate slipper: habitat and method of movement. Breathing and elimination

The ciliate slipper lives in shallow stagnant bodies of water. Its body shape resembles the sole of a shoe, reaches 0.1-0.3 mm in length, and is covered with a strong elastic shell - the pellicle, under which there are skeletal supporting threads in the ecto- and endoplasm. This structure allows the ciliates to maintain a constant body shape.

The organelles of movement are hair-like cilia (the ciliates have 10-15 thousand of them), covering the entire body. When examining cilia using an electron microscope, it was found that each of them consists of several (about 11) fibers. Each cilium is based on a basal body located in the transparent ectoplasm. The shoe moves quickly thanks to the coordinated work of the cilia, which rake in water.

In the cytoplasm of ciliates, ectoplasm and endoplasm are clearly distinguished. In the ectoplasm, between the bases of the paramecium cilia, there are organelles of attack and defense - small fusiform bodies - trichocysts. Electron microscope photographs show that the ejected trichocysts are equipped with nail-like tips. When irritated, the trichocysts are thrown out, turning into a long, elastic thread, striking the enemy or prey.

The endoplasm contains two nuclei (large and small) and systems of digestive and excretory organelles.

Nutrition organoids. On the so-called ventral side there is a pre-oral recess - the peristome, leading to the cellular mouth, which passes into the pharynx (cytopharynx), which opens into the endoplasm. Water with bacteria and unicellular algae, which the ciliates feed on, is driven through the mouth and pharynx by a special group of peristome cilia into the endoplasm, where it is surrounded by a digestive vacuole. The latter gradually moves along the body of the ciliate. As the vacuole moves, the ingested bacteria are digested within an hour, first with an acidic and then with an alkaline reaction. The undigested residue is thrown out through a special opening in the ectoplasm - the powder, or anal pore.

Organoids of osmoregulation. At the anterior and posterior ends of the body, at the border of the ecto- and endoplasm, there is one pulsating vacuole (central reservoir), around which 5-7 afferent tubules are located in a corolla. The vacuole fills with fluid from these afferent canals, after which the fluid-filled vacuole (diastole phase) contracts, pours fluid out through a small hole and collapses (systole phase). Following this, the liquid, which has again filled the adductor channels, pours into the vacuole. The anterior and posterior vacuoles contract alternately. Pulsating vacuoles perform a dual function - the release of excess water, which is necessary to maintain constant osmotic pressure in the body of the paramecium, and the release of dissimilation products.

Nuclear slipper apparatus is represented by at least two qualitatively different nuclei located in the endoplasm. The shape of the kernels is usually oval.

The large vegetative nucleus is called the macronucleus. Transcription occurs in it - the synthesis of informational and other forms of RNA on DNA templates, which go into the cytoplasm, where protein synthesis is carried out on ribosomes.

Small generative - micronucleus. Located next to the macronucleus. In it, before each division, the number of chromosomes doubles, so the micronucleus is considered as a “depot” of hereditary information transmitted from generation to generation.

The slipper ciliate reproduces both asexually and sexually.

In asexual reproduction, the cell is laced in half along the equator and reproduction is carried out by transverse division. This precedes the mitotic division of the small nucleus and the processes characteristic of mitosis in the large nucleus.

After repeated asexual reproduction in the life cycle, the sexual process, or conjugation, occurs.

The sexual process consists of the temporary connection of two individuals through the mouth openings and the exchange of parts of their nuclear apparatus with a small amount of cytoplasm. Large nuclei then fall apart and gradually dissolve in the cytoplasm. Small nuclei first divide twice, the number of chromosomes is reduced, then three of the four nuclei are destroyed and dissolved in the cytoplasm, and the fourth divides again. As a result of this division, two haploid sex nuclei are formed. One of them - migrating, or male - passes into the neighboring individual and merges with the female (stationary) nucleus remaining in it. The same process occurs in the other conjugant. After the fusion of the male and female nuclei, the diploid set of chromosomes is restored and the ciliates diverge. After which, in each ciliate, the new nucleus is divided into two unequal parts, as a result of which a normal nuclear apparatus is formed - a large and small nucleus.

Conjugation does not lead to an increase in the number of individuals. Its biological essence consists in the periodic reorganization of the nuclear apparatus, its renewal and increase in the viability of the ciliate, its adaptability to the environment.

The slipper and some other free-living ciliates feed on bacteria and algae. In turn, ciliates serve as food for fish fry and many invertebrate animals. Sometimes slippers are bred to feed newly hatched fish fry.

The ciliate slipper is a fairly common species that belongs to the group. It lives in fresh, standing water bodies with a sufficient amount of organic materials, which it feeds on. By the way, the structure of the slipper ciliates is considered the most complex of this group of organisms.

general characteristics

The ciliate slipper is a single-celled organism whose shape actually resembles the sole of a shoe and is preserved by a dense outer layer of cytoplasm. The entire body of the animal is covered with a huge number of cilia, which are arranged in longitudinal rows. Their main function is movement.

The ciliate shoe moves with its blunt end forward. The cilia move with a slight delay relative to each other. When moving, the body also rotates around an axis.

Between the cilia there are so-called trichocysts - small spindle-shaped organelles that perform a protective function. Each trichocyst consists of a body and a tip, which, in the presence of a stimulus (collision, heating, cooling), shoot sharply.

Ciliate slipper: structure

The bulk of the body is endoplasm, or the liquid part of the cytoplasm. Ectoplasm is closer to the cytoplasmic membrane, has a denser consistency and forms a pellicle.

Digestion. The ciliate slipper feeds on bacteria and has a rather peculiar cellular structure. Closer to the anterior end of the body there is a perioral funnel, the inner surface of which is covered with a complex system of cilia. The movements of the cilia create a flow, along with which microorganisms are sucked in. Next, the nutritional particles enter the pharynx, which is also lined with cilia, and only then into the mouth. They enter the digestive vacuole through endocytosis. Residues are excreted through a specific organelle - powder.

Genetic material. The ciliate slipper has two nuclei - a large one (macronucleus) and a small one (micronucleus). The micronucleus contains a complete set of genetic information and takes part in the sexual reproduction of the organism. The macronucleus is responsible for the synthesis of protein compounds.

Excretion and respiration. The ciliate slipper is able to exist even at very low oxygen concentrations in water. Oxygen is absorbed by the entire surface.

As already mentioned, this simple organism lives in fresh water and, due to the difference in concentrations, it needs an osmoregulation system. The ciliate has two contractile vacuoles - anterior and posterior, each of which is led by a branched system of tubules. Excess fluid and secondary metabolic products are collected in the tubules and released into the environment by vacuoles. Both organelles contract alternately, once every 15-20 seconds.

Reproduction of ciliates-slippers

This organism is characterized by both sexual and asexual reproduction.

It is carried out by transverse division of the cell into two equal parts. At the same time, the body remains active. This is followed by rather complex regeneration processes, during which each part of the body completes the necessary organelles.

Sexual relations between two individuals occur through conjugation. The ciliates temporarily stick together, and a kind of bridge of cytoplasm is formed between their surfaces. The macronuclei of both organisms are destroyed, and the small nuclei are divided by meiosis.

After this, four nuclei with a haploid set of chromosomes are formed. Then three of them die, and the remaining ones divide by mitosis, forming two protonuclei - female and male. Organisms exchange “male” protonuclei. Then in each there is a fusion of two nuclei and the formation of a syncarion. Then mitosis occurs, after which one of the resulting nuclei becomes a macronucleus, and the second - a micronucleus.

The reproduction of the slipper ciliate is influenced by its more complex and special structure compared to other Protozoa. So, the slipper ciliate has two nuclei. One is big, called macronucleus, the second is small, called micronucleus.

The nuclei contain chromosomes, which contain DNA molecules. They encode hereditary information. In a large nucleus (macronucleus) there are several sets of chromosomes, i.e. this nucleus polyploid. The small nucleus (micronuclius) contains a double set of chromosomes, i.e. this nucleus diploid. For comparison, most other animals have one diploid nucleus in their cells. Only in germ cells nuclei haploid(contain a single set of chromosomes). Diploidy means that each chromosome is duplicated, that is, each chromosome has another chromosome identical to it. Polyploidy means that each chromosome is duplicated several times.

Information is read from the DNA of the macronucleus using special molecules (RNA), and then in the cytoplasm, with the help of RNA, proteins characteristic of the ciliate slipper are synthesized. And then proteins determine the synthesis of fats, carbohydrates and other substances (this is done by proteins that perform the function of enzymes) or cell structures (organelles, membranes, etc.) are built from proteins.

Micronucleus chromosomes are not used to regulate cell activity. The micronucleus is used only for sexual intercourse. The slipper ciliates have not only asexual reproduction, but also sexual reproduction. However, this sexual reproduction does not proceed the same way as in multicellular animals. With it, the number of individuals does not increase. Therefore, it is more correct to call sexual reproduction of ciliates a sexual process ( conjugation).

Asexual reproduction of slipper ciliates

Asexual reproduction of the slipper ciliate proceeds in much the same way as in amoeba and green euglena. The cell divides in two. However, unlike the same euglena, ciliates are divided not in the longitudinal direction, but in the transverse direction. That is, in the slipper ciliate, one daughter cell gets the front part of the cell, and the second gets the back part.

During a favorable time of year (when it is warm and there is a lot of food), division occurs approximately once a day. Asexual reproduction of slipper ciliates occurs only in grown, fully formed individual cells.

Before the cell itself divides, its nuclei first divide. First, the small nucleus divides and two micronuclei are formed. After this, the macronucleus divides. At this time, many vital processes in the ciliate-slipper are suspended (for example, it stops feeding). One large and one small nuclei go to the front of the cell, the other large and small - to the back of the cell.

After nuclear division, the cell itself begins to divide. A constriction forms in the middle, which deepens, completely separating one part of the cell from the other. Each new cell receives one contractile vacuole, and completes the second one independently. The cell mouth and other parts of the cell are also built.

Sexual process of the ciliate slipper

The sexual process (conjugation) involves two different cells of the ciliate slipper. They approach each other from the side of the cell mouths and stick together. A so-called cytoplasmic bridge is formed between them (a channel through which the contents of one cell can flow into another).

Large nuclei of conjugating ciliates are destroyed. In each slipper ciliate, the small nucleus is divided so that four nuclei with a haploid set of chromosomes are formed. This division is called meiosis. Three of the haploid nuclei are destroyed and the remainder is divided in the usual way ( mitosis). But since it had a haploid set of chromosomes, two nuclei with a haploid set are obtained.

From each cell, one haploid nucleus goes through the cytoplasmic bridge into another cell, while the other remains. In this way, slipper ciliates exchange their genetic information. One haploid set remains its own, and the second comes from another cell.

After the exchange of nuclei has occurred, they merge in each cell. A new small diploid nucleus is formed. It then divides, giving rise to a large nucleus, which then becomes polyploid.

During sexual reproduction, including the sexual process, genetic information is exchanged. Individuals may develop new characteristics that contribute to their better adaptability and survival.

Slipper ciliates are a type of protozoan single-celled animals from the class of ciliated ciliates such as ciliates. This species received its name for its resemblance to the sole of a shoe.

Slipper ciliates live in fresh water bodies of any type with stagnant water and the presence of a mass of decomposing organic substances in the water. These organisms are also found in aquariums. You can verify this by taking samples of water with sludge from the aquarium and examining them under a microscope.

The structure of the ciliate-slipper has characteristic features. This is a relatively large organism, body dimensions reaching 0.5 mm. The minimum sizes of individuals are from 0.1 mm. The shape of the body, as already noted, resembles a shoe. The outer shell of this protozoan is the outer membrane. Underneath it is the pellicle - a dense layer of cytoplasm with flattened membrane cisterns (alveoli), microtubules and other components of the cytoskeleton.

The entire surface of the slipper ciliate cell is covered with cilia, the number of which ranges from 10 to 15 thousand. At the base of each cilium there is a so-called basal body. All basal bodies make up the complex cytoskeletal system of the ciliate slipper. Between the cilia there are organelles that perform a protective function - spindle-shaped bodies (trichocysts). Their structure includes a body and a tip, enclosed in a membrane sac. The response of the trichocyst to irritation (heating, contact with a predator) is its immediate elongation (6-8 times) when the outer membrane merges with the membrane sac of the trichocyst, which looks like a “shot”. In the aquatic environment, trichocysts impede the movement of a predator approaching the ciliate. One individual of this species can have from 5 to 8 thousand trichocysts.

The movement of the ciliate-slipper is possible thanks to the wave-like movements of the cilia. So it floats forward with its blunted edge at a speed of approximately 2 mm/s. Basically, the slipper ciliate moves in one plane, while in the thickness of one mass the individual can rotate around the longitudinal axis. Protozoa change directions of movement due to the bends of their body. If the ciliate encounters an obstacle, it immediately begins to move in the opposite direction.

What does the slipper ciliate eat? The nutrition of this protozoan has characteristic features. The basis of the ciliate's diet is bacteria, accumulations of which attract the ciliate by releasing special chemicals. Also, ciliates can swallow other particles suspended in water, even those that do not have much nutritional value. In the body of a protozoan, a cellular mouth is distinguished, which passes into a cellular pharynx. Near the mouth there are special cilia, collected in complex complexes. With the wave-like movements of this type of cilia, food enters the pharynx with a stream of water. A large digestive vacuole forms at the base of the pharynx. This vacuole, like all subsequent newly formed ones, migrates in the cytoplasm of the individual’s body along a certain “path” - from front to back, and then from back to front (as if in a circle), while the large vacuole breaks up into smaller ones. Thus, the absorption of nutrients is accelerated. Digested substances enter the cytoplasm, where they are used for the needs of the body. Unnecessary substances are released into the environment through the powder in the back of the cell - an area with an underdeveloped pellicle.

The ciliate slipper cell has two contractile vacuoles in front and behind the body. In the structure of such a vacuole, a reservoir and tubules are distinguished. Through the tubules, water flows from the cytoplasm into the reservoir, from which it is pushed out through the pore. Thanks to the cytoskeleton of microtubules, this entire complex is constantly located in a certain area of ​​the cell. The main function of contractile vacuoles is osmoregulatory. Through them, excess water is removed from the cell, as well as products of nitrogen metabolism.

The respiration of the slipper ciliates occurs through the entire surface of the body. And with a low oxygen concentration in water, ciliates live through glycolysis.

The two nuclei of the ciliate slipper have different structures and perform different functions. The small nucleus is diploid and has a round shape; the large nucleus is polyploid and bean-shaped. The small nucleus is responsible for sexual reproduction, and the large nucleus directs the synthesis of all proteins in the ciliate slipper cell.

Asexual reproduction occurs by cell division in half. Sexual reproduction occurs through conjugation. The two shoes come together and through complex transformations of the nuclei, new individuals are formed.

The slipper ciliate belongs to the phylum of Ciliates, which belongs to Protozoa (single-celled eukaryotes). Often several similar species are called slipper ciliates. Characteristic features of all ciliates are the presence of cilia (which are organs of movement) and the more complex structure of their cell-organism compared to other protozoa (for example, amoebas and euglena).

The slipper ciliate lives in freshwater, usually polluted, reservoirs. Cell sizes range from 0.2 to 0.6 mm. The body shape is similar to the sole of a shoe. In this case, the front end with which the ciliate swims forward is the “heel of the shoe”; and the "toe" is the back end.

The body of the slipper ciliate is surrounded by cilia. In drawings and diagrams, cilia are shown only around the cell. In fact, they run in kind of cords throughout the body (i.e., also above and below, which we do not see in the flat picture).

The cell moves thanks to the wave-like contractions of the cilia (each next one in the row bends a little later than the previous one). In this case, each eyelash moves sharply in one direction, after which it slowly returns to its place. The speed of movement of ciliates is about 2 mm per second.

The cilia are attached to basal bodies. Moreover, half of them do not have eyelashes. Basal bodies with and without cilia alternate.

The outer part of the cytoplasm (under the cell membrane) has structures that allow the slipper ciliate to maintain its shape. This part of the cytoplasm is called cytoskeleton.

The membrane has trichocysts, which are sticks that are thrown out and “sting” predators attacking ciliates-slippers.

The ciliate slipper cell has a fairly deep depression (as if the membrane is concave into the cell). This formation is called cell mouth, turning into cell pharynx. They are surrounded by longer and thicker cilia that force food into them. Most often, bacteria and single-celled algae serve as food. Ciliates are found by the substances they secrete.

Separated from the cell pharynx digestive vacuoles. Each such vacuole, after its formation, first passes to the back of the cell, then moves to the front, and then again to the back. This movement is ensured by the constant movement of the cytoplasm. Lysosomes and various enzymes approach the digestive vacuole; nutrients in the vacuoles are broken down and enter the cytoplasm. When the digestive vacuole goes around the circle and returns to the back of the cell, its contents will be thrown out through powder.

The ciliate has two slippers contractile vacuoles. One is in the front of the cage, the other is in the back. These vacuoles are more complex than those of Euglena. It consists of a central reservoir and tubules extending from it. Excess water and harmful substances first end up in the tubules, after which they go into the reservoirs. The filled reservoirs are separated from the tubules and, through the surface of the cell, contracting, the solution is released. The vacuoles contract alternately.

The slipper ciliate breathes oxygen dissolved in water. However, with a lack of oxygen, it can switch to oxygen-free breathing.

Slipper ciliates reproduce by dividing cells in two. Unlike Euglena green, the parent cell is divided not along, but across (that is, one daughter cell receives the back part of the parent cell, and the other the front, after which they complete the missing parts).

In addition to the asexual method of reproduction, ciliates have a sexual process. With it, there is no increase in the number of individuals, but an exchange of genetic information occurs.

The slipper ciliate has two nuclei - large (macronucleus) and small (micronucleus). The macronucleus is polyploid (it has several sets of chromosomes). Micronucleus is diploden. The macronucleus is responsible for controlling the life of the cell. On the DNA contained in it, RNA is synthesized, which is responsible for the synthesis of proteins. The micronucleus is responsible for the sexual process.

During the sexual process, two ciliates-slippers approach each other from the side of the cell mouths. A cytoplasmic bridge is formed between cells. At this time, the macronucleus in each cell dissolves, and the micronucleus divides by meiosis. The result is four haploid nuclei. Three of them dissolve, and the rest is divided by mitosis. The result is two haploid nuclei. One of them remains in its cell, and the other goes along the cytoplasmic bridge to another ciliate. One of its haploid nuclei moves from the second ciliate. Next, two nuclei (one our own and one foreign) merge in each cell. The already formed diploid nucleus (micronucleus) then divides to form a macronucleus.