A message on the topic of ciliates slipper. Ciliate slipper: where it lives, structure and functions. Description and characteristics of the organism

Type Ciliates, or Ciliates, are the most complex protozoa. On the surface of the body they have organelles of movement - cilia. There are two nuclei in a ciliate cell: the large nucleus is responsible for nutrition, respiration, movement, and metabolism; The small nucleus is involved in the sexual process.

The structural features and vital functions of ciliates are considered using the example of the slipper ciliate.

Habitat, structure and movement. In the same reservoirs where the amoeba proteus and green euglena live, the slipper ciliate is also found (Fig. 30). This unicellular animal, 0.5 mm long, has a spindle-shaped body, vaguely reminiscent of a shoe. The slipper ciliates are always in motion, swimming with the blunt end forward. The movement speed of this animal reaches 2.5 mm per second.

Rice. 30. Structure of the ciliate-slipper: 1 - cilia; 2 - contractile vacuole; 3 - cytoplasm; 4 - large core; 5 - small core; b - cell membrane; 7 - cell mouth; 8 - cell pharynx; 9 - digestive vacuole; 10 - powder

The body of ciliates is more complex than that of amoeba and euglena. The thin elastic shell covering the outside of the ciliate maintains the constant shape of its body. This is also facilitated by the development of well-developed supporting fibers, which are located in the layer of cytoplasm adjacent to the membrane. There are about 15 thousand oscillating cilia located on the surface of the ciliate's body. At the base of each cilium lies a basal body. The movement of each eyelash consists of a sharp stroke in one direction and a slower, smooth return to its original position. The cilia oscillate approximately 30 times per second and, like oars, push the ciliate forward, the wave-like movement of the cilia is coordinated. When a slipper ciliate swims, it slowly rotates around the longitudinal axis of the body.

Under the elastic shell, special formations are scattered throughout the body - trichocysts (from the Greek trichos - “hair” and cystis - “bubble”). These are short “sticks” located in one layer perpendicular to the surface of the body. In case of danger, the trichocysts are thrown out with force, turning into thin, long elastic threads that hit the predator attacking the shoe. Over time, new trichocysts appear in place of used trichocysts.

Nutrition. On the body of the ciliate there is a depression - a cellular mouth, which passes into the cellular pharynx. Thicker and longer cilia are located near the mouth. They push bacteria into the throat along with the flow of water - the main food of the shoe. At the bottom of the pharynx, food enters the digestive vacuole. Digestive vacuoles move in the body of the ciliate by a current of cytoplasm. In the vacuole, food is digested, the digested products enter the cytoplasm and are used for life. The undigested residues remaining in the digestive vacuole are thrown out at the posterior end of the body through a special structure - powder.

The slipper ciliate finds its prey by sensing the presence of chemicals that release clusters of bacteria.

Selection. In the body of the slipper ciliate there are two contractile vacuoles, which are located at the anterior and posterior ends of the body. Each vacuole consists of a central reservoir and 5-7 channels directed to these reservoirs. First, the channels are filled with liquid, then it enters the central reservoir, and then the liquid is expelled out. The entire cycle of contraction of these vacuoles occurs once in 10-20 seconds. Contractile vacuoles remove harmful substances that are formed in the body and excess water.

Breath. Like other free-living unicellular animals, in ciliates respiration occurs through the integument of the body.

Reproduction. Sexual process. Slipper ciliates usually reproduce asexually - by dividing in two (Fig. 31, A). However, unlike flagellates, ciliates are divided across the body. The nuclei are divided into two parts, and each new ciliate contains one large and one small kernel. Each of the two daughter ciliates receives part of the organelles (for example, contractile vacuoles), while others are formed anew. Slipper ciliates divide once or twice a day.

Rice. 31. Asexual reproduction (A) and sexual process (B) in the ciliate slipper

During the sexual process, the number of individuals does not increase. Two ciliates are temporarily connected to each other (Fig. 31, B). At the point of contact, the membrane dissolves, and a connecting bridge of cytoplasm is formed between the animals. The large core of each ciliate disappears. The small nucleus divides twice, and four daughter nuclei are formed in each ciliate. Three of them are destroyed, and the fourth is divided again. As a result, two nuclei remain in each ciliate. One of these nuclei of each of the two individuals passes through a cytoplasmic bridge into another ciliate (that is, an exchange of nuclei occurs) and there merges with the remaining nucleus. Then, in each ciliate, a large and small nuclei are formed from this newly formed nucleus, and the ciliates disperse. This sexual process is called conjugation. It lasts about 12 hours.

The sexual process leads to renewal, exchange between individuals and redistribution of hereditary (genetic) material, which increases the vitality of organisms.

Rice. 32. Variety of ciliates: 1 - bursaria; 2 - stentor; 3 - stylonychia; 4 - suvoika

Bursaria has one large and long sausage-shaped core, about 30 small nuclei. Most ciliates actively swim, but some of them, for example stylonychia, move along the bottom of a reservoir, along aquatic plants, as if walking on special elongated cilia located on the ventral side of the body . Other ciliates, such as suvoyki, are attached to the bottom or to plants with long stems, which can contract thanks to special contractile fibers. Many suvoikas form colonies. These ciliates feed mainly on bacteria. Sucking ciliates also lead a sedentary, motionless lifestyle. They lack eyelashes. They are equipped with sucking tentacles in the form of thin contractile tubes, which serve to catch prey (mainly other protozoa) and suck out the contents from it. Protozoa that touch the tentacles, such as flagellates, instantly stick to them. And then the contents of the victim are absorbed, as if pumped along the tentacle into the sucking ciliate.

Rice. 33. Protozoa from the stomach of ungulates

Some ciliates live in the intestines of large herbivorous ungulates (Fig. 33). In cows, sheep, goats, antelopes, and deer, ciliates inhabit the anterior sections of the stomach in huge quantities. These ciliates feed on bacteria, starch grains, fungi, and particles of plant tissue. Larger ciliates devour smaller ones. In other parts of the stomach of herbivores, ciliates are digested. Thus, these ciliates benefit those animals in whose stomachs they live. Infusoria infection occurs during group feeding or watering.

Laboratory work No. 1

1. Subject. The structure and movement of the ciliate slipper. Target. To study the features of the structure and movement of the ciliate-slipper.
2. Equipment: microscope, tripod magnifying glass, slide and cover glass, pipette, cotton wool, culture of ciliates in vitro.

Progress

1. Determine whether the slipper ciliates in the test tube are visible to the naked eye.
2. Apply a drop of water with slipper ciliates from a test tube onto a glass slide. Using a magnifying glass, examine the shape of the body, the external structure, the difference between the front and back parts of the body, and the method of movement. Count the number of ciliates in a drop of water.
3. Place two drops of water with ciliates on a glass slide and connect them with a water “bridge”. Place a crystal of salt on the edge of one drop. Explain the phenomena occurring.
4. Place two or three fibers of cotton wool in a drop of water with ciliates (to slow down the movement of ciliates). Cover carefully with a coverslip.
5. Place the specimen under a microscope. Consider first at low and then at high magnification of the microscope what is happening inside the body of the ciliate.
6. Draw the external and internal structure of the slipper ciliate using a high-magnification microscope. Make the necessary designation.
7. Based on observations, list the characteristics characteristic of ciliates as representatives of protozoa.

Ciliates are complexly organized protozoa. They have two nuclei in the cell: large and small. They reproduce asexually and sexually. Sexual reproduction promotes renewal, exchange between individuals and redistribution of hereditary (genetic) material, which increases the vitality of ciliates.

Exercises based on the material covered

1. Why is the slipper ciliate so named?
2. What signs prove the more complex organization of the slipper ciliate compared to amoeba Proteus and Euglena green?
3. How does the ciliate-slipper structure, which is more complex than that of other protozoa, manifest itself in the processes of nutrition and excretion?
4. What are the features of the reproduction process of the slipper ciliates?
5. Why is the sexual process important biologically in the life of the slipper ciliate?

Ciliates can also be found directly in water samples taken from a pond, swamp or ditch, but we will have much more material for observation if we prepare an artificial culture for breeding ciliates in advance - 10-15 days in advance - by providing them with nutritious material.

The food for ciliates in such crops is the smallest hay bacteria, which multiply in huge numbers in the decoction made from hay. When we add pond or swamp water in which ciliates live to such a hay decoction, diluted with water and standing for several days in an open jar, then thanks to the abundance of food, the ciliates will very quickly begin to multiply there and in a week they will be easy to find in every drop placed onto a glass slide. All that remains is to place a thin cover glass on this drop and then examine it under a microscope.

Most often in such hay crops one comes across oblong ciliates-slippers, or paramecia, which quickly sweep through the field of view of the microscope. They can be seen better when they encounter some obstacle in the water, so it is useful, before applying a cover glass, to place a few green threads of algae or a tiny piece of cotton wool torn into individual hairs into the water.

The body of the slipper ciliate consists of one cell, which, however, has a very complex structure (Fig. 27). The main mass of the body consists of protoplasm; inside it there is a rounded core and next to it there is a second, small core. In the protoplasm of ciliates, two layers can be distinguished: the outer layer, which has a fibrous structure, and the inner layer, which is more liquid. Externally, the body of the ciliate is covered with a layer of denser protoplasm and therefore retains a certain shape, characteristic of all ciliates of this species.

The ciliate swims thanks to the movement of numerous small cilia, covering its body on all sides and acting like thousands of small oars. All these eyelashes move - “flicker”, bending in one direction, just as a grain field is agitated by the passing wind.

If you lightly press on the cover glass, you can sometimes observe how, under the influence of mechanical irritation, long thin filaments protrude from the body of the ciliate - trichocysts(Fig. 28). They are apparently poisonous and serve as a means of defense for her.

A surer way to force ciliates to “shoot” their trichocysts is chemical irritation. To cause it, a drop of diluted acetic acid is placed at the edge of the cover glass, and from the opposite edge they begin to suck out water with a piece of filter paper (or “blotter”).

When the acid reaches the body of the ciliate, it responds by throwing out trichocysts (later the action of the acid kills the ciliates).

When observing living ciliates under a microscope, they quickly sweep across the field of view, and in order to examine them, we have to artificially delay their movement. However, we should not forget that the speed of movement of ciliates is only apparent: after all, if we examine the ciliates with a magnification of, say, 100 times, then not only the size of the ciliates itself will be increased 100 times, but also the true length of the path that it has covered in one second time, which means that in reality it moves 100 times slower than it appears to our “armed” eye.

On the outside of the slipper ciliate’s body you can see an oblong notch. This is the oral cavity leading to the pharyngeal canal, which looks like a narrow funnel and ends in the protoplasm. The movement of the cilia covering the edges of the oral cavity drives bacteria and small organic debris into the throat of the ciliate, which it feeds on.

Among the protoplasm, bubbles with small lumps or grains inside are visible here and there - these are digestive vacuoles, that is, bubbles formed around food particles swallowed through the mouth. They slowly move through the protoplasm, the food in them changes and is digested, and the remains are thrown out through the powder - a special “anal” hole that is present in the membrane covering the body (it is difficult to see).

If you add watercolor carmine diluted in water or at least finely ground charcoal in a mortar to a drop of water with ciliates, you can observe how the ciliates swallow particles of such a suspension and how the resulting digestive vacuole moves through their body.

In addition, the slipper ciliate has two special vesicles with narrow tubules arranged radially around them, through which aqueous liquid enters the vesicle and which give the entire organelle a stellate shape. One of these bubbles is located closer to the anterior end of the body, the other - closer to the rear.

Their size changes: the accumulated liquid pours out and the bubble disappears, but then a new accumulation of liquid appears and grows in the same place. These contractile vesicles (vacuoles) play the role of excretory organs. Through them, not only decay products are removed from the body, but also excess water that constantly penetrates from the external environment; thanks to this, a certain concentration of salts necessary for it is maintained in the protoplasm (in ciliates living in sea water, contractile vacuoles are not observed).

Ciliates have no special devices for breathing. The single cell that makes up its body is surrounded on all sides by water containing dissolved oxygen, and gas exchange occurs through the thin membrane of the body.

When there is an abundance of food, ciliates multiply quickly. Reproduction occurs by division: both nuclei (large and small) are extended in length and constrictions are formed on them; the body simultaneously also begins to tighten, and then both halves, together with the halves of the nuclei, are separated by a partition (Fig. 29). Soon both halves separate and begin to live independently.

Under favorable conditions, ciliates can reproduce for a long time through such successive divisions, forming hundreds and thousands of alternating generations. However, sooner or later - probably as conditions worsen - changes occur in their physiological state that cause them to develop a peculiarly pronounced form of sexual reproduction.

Two ciliates that meet are pressed against each other, touching with their oral cavity, and then a very complex restructuring of the entire nuclear apparatus occurs in their body: large nuclei are destroyed, small ones are divided several times, partially also destroyed, and from them each ciliate is left with two reproductive nuclei. One of them - the “female” - remains in place, and the other - the “male” - passes into the body of another ciliate (through the plasma bridge formed between them) and there merges with its “female” nucleus (Fig. 30).

This form of the sexual process in protozoa, when two cells do not merge into one, but mutually exchange parts of their nuclei, is called conjugation. After conjugation, the ciliates disperse, their normal structure is restored, and then they begin to reproduce again by division.

What is observed during the conjugation of ciliates largely reminds us of the fertilization of an egg: in both cases we see the fusion of nuclear substance originating from two different cells. As a result of the fusion of nuclei of different origins, the organisms of both ciliates are “renewed” and their vitality increases.

When unfavorable conditions occur (for example, when a reservoir dries out), many ciliates are covered with a denser shell - a cyst - and in this form they are able to remain for a long time in a state of “hidden life”. A ciliate clad in a cyst, along with dust, can be picked up by the wind and carried to some other body of water. There she will free herself from her shell and begin to lead an active life again.

It is interesting that education cysts(encystment) for a long time it was not possible to detect just the most well-known and, it would seem, especially well-studied ciliates - paramecia, which from this side seemed like some kind of incomprehensible exception among other ciliates. And only in recent years, the Russian researcher Mikhelson managed to see paramecium cysts.

It turned out that they have an angular shape and are similar in appearance to the smallest grains of sand, which is why previous observers did not pay attention to them.

Rice. 27.

A - in a test tube with a milk solution; B - the same test tube viewed through a hand lens; B - shoes under a low magnification microscope; G - a shoe under a high magnification microscope.

Rice. 28.

A - part of a stained section through the paramecium at high magnification (numerous trichocysts lie along the edge of the body); B - normal and “shot” trichocyst at high magnification.

Rice. 29.

1 - oral cavity; 2 - large core; 3 - small core; 4 - contractile vacuole.

Rice. thirty.

1 - beginning of conjugation; each ciliate has both a large and small nucleus (macronucleus and micronucleus), micronuclei in the diagram are conventionally marked with dark and light colors; 2 - macronuclei are destroyed; 3 - micronuclei divide twice, but of the 4 daughter nuclei of each ciliate, 3 are doomed to decay - they are shown crossed out (reduction division); 4 - both ciliates have one micronucleus left; 5 - micronuclei divide, with one daughter nucleus (“female”) remaining in place, and the other (“male”) moving into another individual; 6 and 7 - male nuclei meet with female ones and merge with them; 8 - new macronuclei are formed in the ciliate and both individuals diverge.

Ciliate slipper, paramecium caudate(lat. Paramecium caudatum) - a species of ciliates of the genus Paramecium, the simplest single-celled organism. Usually other species of the genus Paramecium are also called slipper ciliates. Aquatic habitat, found in fresh waters. It received its name for the elongated cilia on the posterior end of the body.

According to another classification scheme, they are placed in the animal kingdom in the order of equiciliates ( Holotricha) subclass of ciliated ciliates ( Ciliata) class Ciliophora type of protozoa ( Protozoa), and according to the third scheme - to the order Hymenostomatida of the subclass Holotrichia. There are also numerous other classification schemes for ciliates.

Structure

The sizes of different types of shoes range from 0.1 to 0.5 mm, Paramecium caudate is usually about 0.2-0.3 mm. The body shape resembles the sole of a shoe. The outer dense layer of cytoplasm (pellicle) includes flat membrane cisterns (alveoli), microtubules and other cytoskeletal elements located under the outer membrane.

On the surface of the cell, cilia are located mainly in longitudinal rows, the number of which is from 10 to 15 thousand. At the base of each cilium there is a basal body, and next to it there is a second one, from which the cilium does not depart. Associated with the basal bodies of ciliates is the infraciliation, a complex cytoskeletal system. In the slipper, it includes postkinetodesmal fibrils extending posteriorly and radiating transversely striated filaments. Near the base of each cilium there is an invagination of the outer membrane - the parasomal sac.

Between the cilia there are small fusiform bodies - trichocysts, which are considered as organelles of protection. They are located in membrane sacs and consist of a body and a tip. The body has a transverse striation with a period of 7 nm. In response to irritation (heating, collision with a predator), the trichocysts shoot out - the membrane sac merges with the outer membrane, and the trichocyst lengthens 8 times in thousandths of a second. It is assumed that trichocysts, swelling in water, can impede the movement of a predator. Mutants of slippers are known that lack trichocysts and are quite viable. In total, the shoe has 5-8 thousand trichocysts. Trichocysts are a type of extrusome organelles with various structures, the presence of which is characteristic of ciliates and some other groups of protists.

The slipper has 2 contractile vacuoles in the anterior and posterior parts of the cell. Each consists of a reservoir and radial channels extending from it. The reservoir sometimes opens outward; the channels are surrounded by a network of thin tubes through which liquid enters them from the cytoplasm. The entire system is held in a certain area by a cytoskeleton made of microtubules.

The shoe has two nuclei of different structure and functions - a diploid micronucleus (small nucleus) of a round shape and a polyploid macronucleus (large nucleus) of a bean shape.

It consists of 6.8% dry matter, of which 58.1% is protein, 31.7% is fat, 3.4% is ash.

Kernel functions

The micronucleus contains a complete set of genes from which almost no mRNA is read and, therefore, its genes are not expressed. When the macronucleus matures, complex genome rearrangements occur; almost all mRNAs are read from the genes contained in this nucleus; therefore, it is the macronucleus that “controls” the synthesis of all proteins in the cell. A shoe with a removed or destroyed micronucleus can live and reproduce asexually, but loses the ability to reproduce sexually. During sexual reproduction, the macronucleus is destroyed and then rebuilt from the diploid primordium.

Movement

By making wave-like movements with the cilia, the shoe moves (floats with the blunt end forward). The eyelash moves in one plane and makes a direct (effective) blow when straightened, and a return blow when curved. Each next eyelash in the row strikes with a slight delay compared to the previous one. Floating in the water, the shoe rotates around its longitudinal axis. Movement speed is about 2 mm/s. The direction of movement can change due to bending of the body. When colliding with an obstacle, the direction of the direct blow is reversed, and the shoe bounces back. Then she “swings” back and forth for a while, and then starts moving forward again. When it encounters an obstacle, the cell membrane depolarizes and calcium ions enter the cell. During the swing phase, calcium is pumped out of the cell.

Nutrition and Digestion

On the body of the ciliate there is a depression - a cellular mouth, which passes into the cellular pharynx. Near the mouth there are specialized cilia of the perioral ciliation, “glued” into complex structures. They push the main food of ciliates - bacteria - into the throat along with the flow of water. The ciliate finds its prey by sensing the presence of chemicals that release clusters of bacteria.

At the bottom of the pharynx, food enters the digestive vacuole. Digestive vacuoles move in the body of the ciliate by a current of cytoplasm along a certain “route” - first to the rear end of the cell, then to the front and then again to the rear. In the vacuole, food is digested, and the digested products enter the cytoplasm and are used for the life of the ciliate. First, the internal environment in the digestive vacuole becomes acidic due to the fusion of lysosomes with it, then it becomes more alkaline. As the vacuole migrates, small membrane vesicles separate from it (probably thereby increasing the rate of absorption of digested food). The undigested food remains inside the digestive vacuole are thrown out in the posterior part of the body through a special area of ​​the cell surface, devoid of a developed pellicle - cytopig, or powder. After merging with the outer membrane, the digestive vacuole immediately separates from it, breaking up into many small vesicles, which migrate along the surface of the microtubules to the bottom of the cell pharynx, forming the next vacuole there.

Respiration, elimination, osmoregulation

The shoe breathes throughout the entire surface of the cage. It is able to exist due to glycolysis at low oxygen concentrations in water. Products of nitrogen metabolism are also excreted through the cell surface and partially through the contractile vacuole.

The main function of contractile vacuoles is osmoregulatory. They remove excess water from the cell, which penetrates there through osmosis. First, the leading channels swell, then the water from them is pumped into the reservoir. When the reservoir contracts, it is separated from the supply channels, and water is released through the pore. Two vacuoles work in antiphase, each contracting once every 10-15 s under normal physiological conditions. In an hour, vacuoles release a volume of water from the cell approximately equal to the volume of the cell.

Reproduction

The slipper has asexual and sexual reproduction (sexual process). Asexual reproduction - transverse division in the active state. It is accompanied by complex regeneration processes. For example, one of the individuals re-forms a cellular mouth with a perioral ciliation, each completes the missing contractile vacuole, the basal bodies multiply and new cilia form, etc.

The sexual process, like that of other ciliates, occurs in the form of conjugation. Shoes belonging to different clones are temporarily “glued together” by their oral sides, and a cytoplasmic bridge is formed between the cells. Then the macronuclei of the conjugating ciliates are destroyed, and the micronuclei divide by meiosis. Of the four haploid nuclei formed, three die, and the remaining one divides by mitosis. Each ciliate now has two haploid pronuclei - one of them is female (stationary), and the other is male (migratory). Ciliates exchange male pronuclei, while female pronuclei remain in “their” cell. Then, in each ciliate, “its own” female and “foreign” male pronuclei merge, forming a diploid nucleus - a synkaryon. When a synkaryon divides, two nuclei are formed. One of them becomes a diploid micronucleus, and the second turns into a polyploid macronucleus. In reality, this process is more complicated and is accompanied by special post-conjugation divisions.

Genome

The shoe genome contains 40 thousand genes, while humans have 25 thousand.

Sources

Notes

Wikimedia Foundation. 2010.

See what “Ciliate slipper” is in other dictionaries:

- (Paramecium caudatum) ... Wikipedia

Infusoria slipper, ciliates slipper... Spelling dictionary-reference book

Slipper, paramecium, stentor, opalina, polygastrica, chilodon, honotricha, endodiniomorph, psammon, suvoika Dictionary of Russian synonyms. ciliates noun, number of synonyms: 24 acineta (1) ... Synonym dictionary

Noun, number of synonyms: 4 ballet (1) ciliate (24) paramecium (2) ... Synonym dictionary

Everyone remembers this creature, with a bright, memorable name, from school. The habitat of the ciliate slipper determines many of its life processes. We will consider the structural and physiological features of this organism in our article.

Habitat of the ciliate slipper: description

The named single-celled organism, whose single cell resembles the sole of a shoe, can only be found in shallow fresh water bodies. Ciliates prefer stagnant water, which contains decaying remains of organic matter. Such a habitat for the slipper ciliate (the photo below shows the shape of the cell) allows it to actively move in search of food.

How to grow ciliates

The cell of ciliates is quite large in size for representatives of this systematic group - up to 0.5 mm. But you can only see it well under a microscope. If you decide to do this, then ready-made samples can be taken even in a regular aquarium.

Anyone can grow a culture of ciliates on their own. To do this, you need to take a base - some water from an aquarium or a coastal part of a reservoir. Place a drop of this liquid on a glass slide and examine it under a microscope. If you find ciliates, this base can be used. Next, the liquid must be placed on the glass, and on both sides - a drop of clean water and salt. Then we connect everything with a match, forming a so-called bridge. Under such conditions, ciliates will begin to move into clean water. This culture is pipetted into a container for further cultivation - it can be any jar of clean water.

To grow, ciliates need a nutrient solution. To prepare it, you need to take some hay and boil it for about 20 minutes in one liter of water. After this, only spores of Bacillus subtilis will remain in the solution, and all other microorganisms will die. The resulting liquid needs to sit for 3 days. During this time, the spores will develop into which will be an excellent food for ciliates. These single-celled animals can also be fed with boiled or condensed milk and infusion with hydrolytic yeast. How to understand that ciliates need to be fed? If the liquid in the jar becomes clear, it means it’s time to eat.

Movement of ciliates

The slipper ciliates allow it to move actively. It carries out this process with the help of specialized organelles - cilia. There are about 15 thousand of them on the surface of one ciliate. Their coordinated work allows the creature to reach speeds of up to 3 mm/s.

The work of the cilia resembles the movement of oars or a pendulum. The movement organelles rise sharply and then smoothly return to their place. In one second, the ciliate makes up to several dozen similar movements. The ciliate moves with its blunt end forward, simultaneously turning around the axis of its body.

Power supplies

According to the type of nutrition, this organism belongs to the group of heterotrophs. The source of finished organic substances is the habitat of the ciliate slipper. Nutrition is carried out using specialized vacuoles. And the basis of the diet is the cells of bacteria and plants, which are found in large quantities in contaminated water. Their ciliates are captured using a small depression - a cellular mouth.

Next, the food enters a kind of pharynx and ends up in the cytoplasm. A digestive vacuole begins to form around it, in which the digestion process occurs. Substances in this organelle are exposed to hydrolytic enzymes. Undigested food remains are removed from the ciliate cell through a hole called powder.

Metabolism

The habitat of the ciliate slipper is a liquid with a certain content of various substances, including salts. In the cytoplasm itself their concentration is much lower. Therefore, water continuously flows from the environment into the cell.

Regulation of this process is carried out with the help of ciliates. There are two of them in the ciliate cell: at the posterior and anterior ends of the body. These are pulsating round cavities, from which tubules extend radially in all directions. Contractile vacuoles are maintained at a constant level.

Gas exchange in ciliates occurs over the entire surface of the body. Oxygen enters the cytoplasm through the membrane. Here the oxidation of organic substances occurs, releasing energy, water and carbon dioxide. Metabolic products are also removed through the membrane.

Reproduction methods

All life processes are determined by the habitat of the ciliate slipper. Reproduction is no exception. So, at a comfortable temperature, the cells of ciliates divide in two. This process begins with crushing the kernel. Each of the daughter cells receives only part of the organelles, and the missing ones are restored.

When the water temperature drops or there is a lack of food, ciliates begin the sexual process. It's called conjugation. In this case, the two ciliates come closer to each other, and a cytoplasmic bridge is formed between them. This is where genetic information is exchanged. As a result, the number of individuals does not change. The significance of this process lies in the renewal of hereditary material, which significantly increases the adaptive capacity of organisms.

The aquatic habitat of the ciliate slipper provides the necessary conditions for the implementation of all processes of its life activity: active movement, heterotrophic nutrition, aerobic respiration and various types of reproduction.

These are the most complex protozoa. The characteristic features of the organization of ciliates are: movement with the help eyelashes, Availability two cores - large And littleth – with different functions and sexual process - conjugation.

Slipper ciliates ( Paramecium caudatum ) - inhabitant of small stagnant bodies of water. Its length reaches 0.1 – 0.3 mm. It is covered with a pellicle, so the shape of the body is constant and resembles an elegant lady's shoe, hence its name (Fig. 5).

2 4 3

Fig 5. Slipper ciliates: 1 – cilia; 2 – digestive vacuoles; 3 – large nucleus (macronucleus); 4 – small nucleus (micronucleus); 5 – powder; 6 – contractile vacuole.

Movement Shoes are formed using numerous (more than 10 thousand) cilia arranged in regular longitudinal rows. They perform coordinated wave-like oscillations.

Nutrition happens as follows. On one side of the body of the shoe there is a funnel-shaped depression leading in the mouth and tubular throat. With the help of cilia lining the funnel, food particles (bacteria, unicellular algae, detritus) are driven into the mouth and then into the pharynx. From the pharynx, food penetrates into the cytoplasm by phagocytosis. The resulting digestive vacuole is picked up by a circular current of the cytoplasm. Within 1 - 1.5 hours, food is digested, absorbed into the cytoplasm, and undigested residues through the hole in the pellicle - powder - are brought out. Under favorable temperature and food conditions, a shoe can consume as much food per day as it weighs.

Contractile vacuoles There are two shoes in the cytoplasm: in the anterior and posterior parts of the body. They are more complexly structured than the simplest of other classes. Water and waste products from the cytoplasm first penetrate into the afferent tubules, and then from them into the central vacuole, from where they are discharged out. The vacuoles contract alternately every 20–30 s.

Rice. 6. Asexual reproduction by transverse division of the slipper ciliates: 1 – micronucleus; 2 – macronucleus.

The nuclear apparatus of the ciliate slipper is complex and is represented by a large bean-shaped polyploid nucleus, or macronucleus, regulating autonomic functions (nutrition, respiration, excretion), and the small nucleus, or micronucleussom, playing a special role in the sexual process.

Reproduction asexual. First, both nuclei divide: the large one amitotically, and the small one mitotically, and then the body of the ciliate slipper divides in half in the transverse direction. The missing organelles develop anew in both daughter individuals (Fig. 6).

Asexual reproduction after a number of generations is replaced by periodically occurring sexual process - conjugationto her. In this case, two ciliates are applied to each other with the sides where the mouth is located. The pellicle at the site of contact between individuals dissolves, and a cytoplasmic bridge is formed between them. The large nucleus is destroyed and does not take part in the sexual process. Small nuclei divide meiotically. Of the four haploid nuclei formed in each ciliate, three disintegrate. The remaining fourth nucleus divides mitotically one more time. One of the two formed nuclei (stationary) remains in the same ciliate, and the other (migrating) passes into the cell of the conjugation partner. After the fusion of the stationary and migrating nuclei, a diploid nucleus with recombined genetic material is formed. In each of the ciliates, the diploid nucleus is divided several times, and after a series of transformations, a small and a renewed large nucleus are formed. After some time, the ciliates begin active asexual reproduction by division.

Control questions:

What are the main features of the external and internal structure that are characteristic of the ciliate slipper?

What types of reproduction are typical for ciliates?

What is the role of the conjugation process, how does it occur?