Protozoa are a source of food for other animals. In the seas and in fresh water Protozoa, primarily ciliates and flagellates, serve as food for small multicellular animals. Worms, mollusks, small crustaceans, as well as the fry of many fish feed primarily on single-celled organisms; Without protozoa, their existence would be impossible. These multicellular animals, in turn, feed on larger animals, and primarily on growing fish fry. It's clear what great value have the simplest in the life of nature and in the national economy.
The largest animal that has ever lived on Earth, the blue whale, feeds on very small crustaceans that inhabit the oceans. Other toothless whales also feed on them. And these crustaceans, in turn, feed on single-celled animals. So it turns out that, ultimately, the existence of whales depends on single-celled animals and plants.
Protozoa are participants in the formation of rocks. Examining a crushed piece of ordinary writing chalk under a microscope, you can see that it consists mainly of small shells of some animals. Many calcareous stones consist of the same microscopic shells. rocks Volga region, Urals, Crimea, Caucasus. Each such shell once contained the body of a simple animal - a foraminifera, which lived in ancient times on the bottom of seas and oceans.
And even now, a significant part of the ocean floor is covered with silt consisting of foraminifera shells. Many limestones consist almost entirely of such shells. Limestones have long had a huge practical significance How construction material. For example, gigantic ancient structures - the Egyptian pyramids - were built from them.
2. Signs of animal organisms. Characteristics of the kingdom Animals (Zoa). Organization of animals of the type Cnidaria. Peculiarities of biology of representatives of the classes Hydrozoa, Scyphozoa and Coral polyps(Anthozoa). Biological and practical significance of coelenterates.
3. Type Flatworms(Plathelminthes). Dismemberment of the body. Structure of organ systems. Representatives of the classes Ciliated (Turbellaria), Flukes (Trematoda), Tapeworms(Cestoda). Features of life activity and development in connection with lifestyle. Development cycles of species using the example of planaria, liver fluke, and bovine tapeworm.
body leaf-shaped or ribbon-shaped, flattened in the dorsoventral direction;
Skin-muscular the sac consists of skin epithelium
Leah, who lost cellular structure(tegument), under co‑
which contains three layers of smooth muscles (circular, longitudinal and diagonal);
absence of body cavity. The space between the internal
These organs are filled with parenchyma cells, which perform supporting, excretory and storage functions.
bilateral symmetry;
three-layer, those. development of organ systems from ectoderm, endoderm and mesoderm;
Digestive system represented by the foregut of ectodermal origin (mouth, pharynx, esophagus) and the midgut of endodermal origin
niya, closed blindly. The hindgut and anus are absent. Digestion of food and absorption of nutrients occurs in the intestines. Undigested residues
food ki are expelled through the mouth. ^ In tapeworms digestive system absent. They feed on the entire surface of the body with the help of microtrichia;
Excretory system protonephridial type. It is represented by stellate-shaped terminal cells and branching tubules extending from them. Channel‑
cells start from terminal cells; they contain bundles of oscillating cilia (ciliary flame). Terminal cells have slit-like openings through which disintegration products enter the lumen from the parenchyma.
simulation. Flickering flame provides advancement
fluid in the tubules. The tubules merge with each other, forming two lateral canals that open outwards with excretory pores. Protonephridia remove pro-
dissimilation products and regulate osmotic pressure;
Nervous system scalene-nodal type (orthogon). Represented by a peripharyngeal nerve ring connecting the suprapharyngeal and subpharyngeal ganglion
glia, and the longitudinal nerve trunks extending from it
lami, of which the lateral ones are the most developed. Nervous
They are connected by commissures. Of the sense organs, the or-
the senses of touch and chemical sense;
Reproductive system well developed. The vast majority of flatworms are hermaphrodite
You. Cross fertilization.
Lack of circulatory system
The phylum Flatworms includes three classes: Ciliated worms ( Turbellaria), Flukes ( Trematoda) and Tapeworms ( Cestoda). Representatives of the classes Flukes and Tapeworms are of medical importance.
^ 110. Class Flukes. Class characteristics. Representatives of medical significance. Prevalence in the Republic of Belarus.
Class Flukes (Trematoda). Trematodes (or flukes) are small helminths (from 2 to 80 mm) with a flat, leaf-shaped body, devoid of articulations. The sexually mature stage of flukes is called Marita. Marita has two suckers, one of which surrounds the oral opening, and the second, abdominal, serves as an attachment organ.
^ Covers of the body. The body wall is made up of a skin-muscular sac, consisting of a tegument (outer covering) fused with the underlying muscles. The tegument is formed from a layer of cells fused together to form a total mass of protoplasm (syncytium). The outer part of the tegument consists of anucleate cytoplasm containing big number mitochondria; deep inner part The tegument contains nuclei. Under the tegument there is a basement membrane, behind which there are smooth muscles, consisting of circular, diagonal and longitudinal muscle fibers.
^ Reproductive system. Most flukes are hermaphrodites. Blood flukes are dioecious.
Male reproductive system consists of a pair of branching or compact testes, two vas deferens, merging into the ejaculatory canal, which
lies on the surface of the copulatory organ (cirrus).
^ Female reproductive system is arranged in a complex manner. The ovary (unpaired), vitelline, spermatheca open into the ootype, where fertilization and the final formation of fertilized eggs take place. Nutrient material for eggs comes from the vitellaria. This also includes the secretions of special glands - Melisa corpuscles. From the ootype, eggs move to the uterus, where
promotes their maturation and is expelled through the genital opening. The egg has characteristic features: its shape is oval, at one pole there is a cap through which the larva emerges.
In some flukes, fertilization occurs in the spermatic receptacle. Insemination is usually cross-breeding. Self-insemination is less common. Flukes are very prolific. Within a week, one individual produces about 1 million eggs.
Life cycle complex, with a change of hosts and several generations of larval stages. All species of this class are biohelminths. The final host is vertebrates and humans, the intermediate, obligatory host is mollusks. Some trematodes, in addition, have a second intermediate host, which can be lower vertebrates and representatives various groups invertebrates. Characteristic feature The life cycle is the reproduction of larval stages through parthenogenesis.
The sexually mature form, marita, lays eggs that are carried outside. For further development the egg should fall into the water. The first larva emerges from the egg - miracidium(has an oval shape, ciliated cover, 2 pigment eyes at the anterior end of the body and protonephridia; in the posterior part of the body of the miracidium there are germ cells that give rise to the next generation of larval forms). Miracidium floats in the water and actively penetrates the body of the mollusk. In the liver the mollusk
as the miracidium turns into a sac-like sporocyst, within which the germ cells are preserved. Then, from the germ cell of the sporocyst, the next stage of larvae develops parthenogenetically - redia(has an elongated body, pharynx, intestinal rudiments, nervous and excretory systems and also contains germ cells). In the body of the redia, the next generation of larvae is parthenogenetically formed from the germ cells - cercariae(they have a body with a tail appendage, 2 suckers, an intestine, an excretory system, and the rudiment of the reproductive system). At the anterior end of the body, some forms have a sharp stylet or a bunch of spines that perform a perforating function, and a group of penetration glands. Cercariae have developed all organ systems with the exception of the reproductive system.
filamentous, formed by the host organism. In those trematodes that have one intermediate host (liver fluke, fasciolopsis), the cercaria encysts in the external environment and is called adolescaria.
Metacercaria and adolescaria are invasive stages for the final host, in whose body they turn into marita.
The invasive stage of blood flukes for the definitive host is the cercariae, which actively invades the host’s body through the skin.
A group of diseases caused by trematodes is called trematodes. Complex environmental conditions on the territory of the Republic of Bashkortostan are favorable for the entire development cycle of liver, feline and lanceolate flukes. They are unfavorable for the development of pulmonary and blood flukes, but increased migration of the population not only within Russia, but from countries far and near abroad, endemic for paragonimiasis and schistosomiasis, contributes to the importation of these trematodes into the territory of the republic.
The following representatives of trematodes are of medical importance: liver fluke (Fasciola hepatica), cat fluke (Opisthorchis felineus), pulmonary fluke (Paragonimus westermani), blood flukes (Schistosoma haematobium, Schistosoma mansoni, Schistosoma japonicum).
Class Flukes. Lanciform fluke. Systematic position, morphophysiological characteristics, life cycle, invasive stage, route of invasion, invasion factors, localization, pathogenic effect. Laboratory diagnostics and measures for public and personal prevention of dicroceliosis. Prevalence in the Republic of Belarus.
^ Lanceolate fluke - Dicrocelium lanceatum- causative agent of dicroceliosis (biohelminthiasis)
Geographical distribution - ubiquitous.
Development cycle. Biohelminth. The main host is herbivorous mammals. The first intermediate host is terrestrial mollusks of the genera Zebrina, Helicela etc. The second one is the ants . Formica. Sporocysts of the first and second order develop in the body of the mollusk; there is no redia stage. The cercariae stick together, form collective cysts, and are released onto the plants. Metacercariae develop in the body of ants.
When the air temperature drops, infested ants move to the tops of plants and fall into a kind of torpor. Infection of humans and animals occurs when ants are accidentally ingested with grass.
Localization. In the liver of large and small cattle and some other animals; very rare in humans.
Pathogenic effect similar to other liver flukes.
Laboratory diagnostics. Microscopy of feces and duodenal contents. Eggs are found. The eggs have an elongated oval shape and are always asymmetrical. The shell is thick, smooth, with a wide, slightly flattened cap at the narrowed pole of the egg. A mature egg is dark brown, an unripe egg is light yellow. Dimensions 38 - 45 ´ 25 - 30 microns.
It is necessary to remember about the possibility of transit eggs getting into gastrointestinal tract humans along with the eaten liver of domestic animals suffering from dicroceliosis.
Prevention. Measures to prevent dicroceliosis have not been sufficiently developed. Sometimes ants are controlled in grazing areas. However, such measures can lead to other undesirable consequences, since ants are important soil formers and human assistants in the fight against insect pests. The destruction of shellfish and deworming of livestock are also important.
^ 116. Class Tapeworms. Class characteristics. Representatives of medical significance. Prevalence in the Republic of Belarus.
Morphology. Cestodes have a flat, ribbon-like body. The body length and number of segments vary greatly among different species (from 1 mm to 10 - 18 m). At the front end there is a head - scolex, Further neck and then strobila, consisting of segments - proglottid. Scolex equipped with devices for attachment to the intestinal walls - suckers, and in some species, hooks (order of tapeworms) or suction slits - bothria (order of tapeworms). The cervix is
is a growth zone. New proglottids bud from the neck, causing the previously formed ones to move back.
^ Nervous and excretory systems have the same structure as those of trematodes. The nervous system and sensory organs are poorly developed. The excretory system is represented by protonephridia. Unlike trematodes, cestodes in excretory system two excretory ducts that run along the sides of the body and open outward into the excretory pore. Blood and respiratory systems No.
^ Reproductive system in the proglottids closest to the neck, it is still absent, but as the segments grow, it begins to develop. The male ones appear first, then female organs. Hermaphroditic proglottids in the middle part of the strobila reach sexual maturity.
^ Male reproductive system:a large number of vesicular testes, the ducts of which merge into a common ejaculatory canal ending in the cirrus.
^ Female reproductive system. In the ootype, the vagina, ovarian ducts, vitelline ducts, and Melis corpuscles open. Fertilized eggs enter the uterus. The uterus may have different shape: sometimes a tube folded into loops ending in an outlet (wide tape) through which the eggs exit into the external environment, sometimes it is a tube ending blindly; some have a sac-shaped uterus. Young proglottids do not have a reproductive system. In the hermaphroditic segments, the formation of reproductive products, fertilization and the formation of eggs occur, which move to the uterus, where their maturation begins. As eggs arrive, the uterus increases in size (with the exception of forms that have an outlet in the uterus) and gradually fills the entire segment, displacing the remaining organs of the reproductive system. Such a segment is called “mature”. As the worm grows, the rear, mature segments gradually tear off, and new, young segments are formed from the neck.
^ Life cycles cestodes are quite complex; they necessarily have two larval stages - oncosphere and finna.
Oncosphere develops in the egg while it is still in the uterus. This is a six-hooked, spherical embryo. Outside, the oncosphere is covered with a thick shell with radial striations. In the intestine of the intermediate host, the oncosphere emerges from the membranes and, with the help of hooks, penetrates into blood vessels and is carried by the blood into various tissues and organs, where it turns into the next larval stage - Finn:
Cysticercus- Finn in the form of a bladder filled with liquid, into which one scolex (bovine and pork tapeworm) is inserted.
Tsenur - bubble with several screwed-in heads.
Cysticercoid in front has a
the widest part with an inverted scolex, and at the back - the tail
tomato appendage (dwarf tapeworm).
Echinococcus - Finn in the form of a large maternal bladder with daughter and grandchild bladders, inside of which a large number of scolex develop.
Plerocercoid- worm-like larva, at the anterior end of which there are two suction grooves (bothria).
Procercoid- wide tape
Larvocyst alveococcus - multi-chambered bladder
Finns develop into adults in the intestines of definitive hosts, which are infected by eating the meat of intermediate hosts. Under the influence of digestive juices, the scolex turns outward from the bladder, attaches to the intestinal wall, and proglottids begin to bud from the neck.
In the larval stage, Echinococcus parasites in the human body ( Echinococcus granulosis) and alveococcus ( Alveococcus multilacularis)(liver, lungs, brain, rarely – spleen, kidneys, bones, muscles). Methods for specific and additional diagnostics of alveococcosis and echinococcosis: latex agglutination reaction (RAL) with echinococcal antigen, indirect hemoagglutination reaction (IRHA) with erythrocyte diagnosticum, flocculation reaction with bentonin (RFB); allergy test; X-ray method, ultrasound, tomography, radioisotope scanning.
For dwarf tapeworm ( Hymenolepis nana) man is both final and intermediate host. Laboratory diagnosis of hymenolipedosis is based on the detection of eggs in feces.
Diseases caused by cestodes are called cestodes.
^ Pathogenic effect of cestodes - toxic-allergic and mechanical (violation of the integrity of the intestinal wall by suction cups, hooks, pinching of the wide tapeworm by bothria, pressure on the organs and tissues of the larvocysts of echinococcus and alveococcus) and absorption of the host’s digested food and vitamins (wide tapeworm).
In the section on the question what is the significance of protozoa in nature??? given by the author Dasha Khoreva the best answer is Protozoa are a source of food for other animals. In the seas and fresh waters, protozoa, primarily ciliates and flagellates, serve as food for small multicellular animals. Worms, mollusks, small crustaceans, as well as the fry of many fish feed primarily on single-celled organisms; Without protozoa, their existence would be impossible. These multicellular animals, in turn, feed on larger animals, and primarily on growing fish fry. It is clear how important protozoa are in the life of nature and in the national economy.
The largest animal that has ever lived on Earth, the blue whale, feeds on very small crustaceans that inhabit the oceans. Other toothless whales also feed on them. And these crustaceans, in turn, feed on single-celled animals. So it turns out that, ultimately, the existence of whales depends on single-celled animals and plants.
Protozoa are participants in the formation of rocks. Examining a crushed piece of ordinary writing chalk under a microscope, you can see that it consists mainly of small shells of some animals. Many calcareous rocks of the Volga region, the Urals, Crimea, and the Caucasus consist of the same microscopic shells. Each such shell once contained the body of a simple animal - a foraminifera, which lived in ancient times on the bottom of seas and oceans.
And even now, a significant part of the ocean floor is covered with silt consisting of foraminifera shells. Many limestones consist almost entirely of such shells. Limestone has long been of great practical importance as a building material. For example, gigantic ancient structures - the Egyptian pyramids - were built from them.
Answer from Alexandra Alyokhina[newbie]
Link in the food chain, water purification, objects of research, cause diseases, live in symbiosis, form sedimentary rocks.
1. A source of food for other animals. (They form the first link in the food chain).
2. They act as orderlies, cleaning water bodies from bacteria and rotting substances.
3. Serve as indicators of water purity.
4. Promote geological exploration and serve as guidelines for oil and gas exploration.
5. Participate in the formation of limestone deposits.
6. Participate in the cycle of substances.
7. They influence soil-forming processes.
Pathogens of diseases in domestic animals and humans.
Protozoa - the creators of sushi
Word protozoa We usually associate it with tiny, invisible lumps of protoplasm. They live, feed, reproduce, but what do we care about them - they are so tiny? Few people know that it is to the simplest that we owe the emergence of entire layers of geological rocks, and often mountain ranges!
Freshwater testate amoebae protect their body with a shell of silicate or calcareous plates secreted by the cytoplasm onto the cell surface. In Arcella, the shell has the shape of a saucer, in the center of which there is an orifice - a hole through which the pseudopods of the amoeba protrude out. Difflugia uses microscopic grains of sand or fragments of the skeleton of diatoms to build shells. The construction of the difflugia house can be observed (of course, only under a microscope) during its reproduction. Before dividing, the protozoan cell gains a lot of water and protrudes from the mouth of the shell. It can be seen how diffusion collects grains of sand and fragments of algae shells with its pseudopods. Solid particles are collected on the surface of the cytoplasm and glued together into a shell for the daughter cell using a special solidifying liquid.
These testate amoebae live in shallow stagnant bodies of water - ponds, ditches, deep puddles. Their numbers are small, and they<постройки>do not create significant bottom sediments. A completely different matter is marine protozoa, which played a colossal role in the creation of the earth's land. Radiolarians build their delicate skeleton from silicon salts absorbed from seawater. Radiolarians are planktonic organisms, their life proceeds in a state of floating in sea water, therefore, the structure of their skeleton must combine lightness and strength, which is achieved by an openwork structure that increases the surface. The variety of radiolarian skeletal shapes is amazing; these creatures are one of the most beautiful and graceful organisms on Earth. Famous German zoologist and evolutionist of the 19th century. E. Haeckel, who was a good artist, dedicated a large section of his atlas of drawings to them<Красота форм в природе>.
The skeletons of other marine shell protozoa - foraminifera - reach great complexity and diversity. In the seas and oceans, foraminifera can be found in all latitudes and at all depths, but their greatest diversity is observed in the bottom layers at depths of up to 200-300 m. The shells of some foraminifera, like those of difflugia, consist of foreign particles - grains of sand. Foraminifera ingest sand grains and then release them onto the cell surface, where they<приклеиваются>to the outer layer of the cytoplasm. Another, most of the foraminifera have calcareous shells. These shells are built from substances from the animals' own bodies, which are capable of concentrating calcium salts contained in seawater in the cell.
At the bottom of the seas and oceans, dead shells of foraminifera of the genus Globigerina form calcareous silt, which is called blue, or globigerina. True, not all shells reach the bottom. It is calculated that with a size of 0.4 mm, foraminiferal shells descend at a speed of 2 cm/s, i.e. in order to dive to a depth of 1000 m, they need 14 hours. During this time, many of them simply dissolve in sea water, so the growth of blue silt is very slow, on average by 0.5-2 cm per 100 years. Nevertheless, such silt covers an area of 120 million km2, i.e. about a third of the world's ocean floor. In some places the thickness of the silt reaches several hundred meters. In the thickness of the silt they go chemical processes, which transform it into chalk, limestone and other sedimentary rocks.
Until recently, there was an opinion that the chalk was formed entirely by foraminiferal shells. However, in fact, the silt also includes the shells of unicellular flagellates, and chalk as such consists of 90-98% of the calcareous shells of coccolithophorid flagellates. Each shell, or coccosphere, consists of 10-20 interconnected calcareous scutes. The number of such shields in 1 cm3 of writing chalk is calculated in astronomical figures - 1010-1011. One line drawn with school chalk on a blackboard contains the remains of many millions of fossil protozoa.
Over tens and hundreds of millions of years, as a result of geological processes, a monolithic rock - limestone - was formed from deposits of protozoan shells. As a result of geological uplifts of areas of the seabed, mountains of limestone appeared on the surface of the land. The Libyan massif is made of limestone, from which the ancient Egyptians extracted material for the construction of the pyramids of the pharaohs. The palaces and temples of Vladimir-Suzdal Rus' and white-stone Moscow were also built from such limestones. Limestones are the main rock that makes up the Alps and Pyrenees, the mountains and highlands of North Africa. A belt of limestone mountains stretches from the Himalayas to Central Asia and to the Caucasus.
Certain groups of extinct foraminiferal species are associated with oil-bearing formations. By species composition The remains of foraminifera discovered during drilling in sedimentary rocks formed over millions of years by deposits of the shells of these animals can predict whether there are oil-bearing strata in a given place or not.
But the skeletons of dead radiolarians, settling to the bottom, form other sedimentary rocks - radiolarites, which include, for example, jasper, opals, chalcedony, siliceous shales and clays. The jaspers of the Caucasus, siliceous rocks in the Urals, the Far East (Sikhote-Alin) and Central Asia consist entirely of radiolarites.
Project language:
Unicellular animals or protozoa - Varieties of protozoa - The role of unicellular animals in the life of nature and humans
Unicellular animals or protozoa
Single-celled animals live in bodies of water, dew drops on plant leaves, in moist soil, in the organs of plants, animals and humans.
The body of the protozoan consists of cytoplasm, on top of which there is a thin outer membrane, and in most, a dense shell. The cytoplasm contains a nucleus (one, two or more), digestive and contractile (one, two or more) vacuoles. Most protozoa actively move with the help of special organelles.
The subkingdom of protozoa includes 40 thousand species, combined into several types. The largest of them are two: the Sarcodaceae and Flagellates type and the Ciliates type.
Phylum sarcodaceae and flagellates
Sarcodidae and flagellates are mainly free-living organisms. The most common of them are amoeba vulgaris and green euglena. Amoeba ordinary lives in bottom areas of fresh water bodies. It does not have a constant body shape and moves by flowing into the resulting protrusions - pseudopods (in Greek, “amoeba” means “changeable”). Euglena green lives in the upper layers of fresh water bodies. It has a dense shell, giving it a permanent spindle-shaped body shape; moves with the help of a flagellum. Inside the body of the euglena there is a nucleus, chloroplasts, a contractile vacuole, and a photosensitive eye.
Amoebas and other protozoa that do not have a shell and are capable of forming pseudopods are classified as sarcodes (from the Greek “sarcos” - plasma). Euglena and other protozoa that have flagella are classified as flagellates. Some flagellates, for example the flagellated amoeba, have flagella and pseudopods, which indicates a close relationship between sarcodidae and flagellates and serves as the basis for combining them into one type.
Nutrition. The common amoeba feeds mainly single-celled organisms, capturing them with pseudopods. Food is digested in digestive vacuoles under the influence of digestive juice. At the same time, complex organic substances of food are transformed into less complex ones and pass into the cytoplasm (they are used to form their own organic substances, which serve as building materials and a source of energy). Undigested food remains are excreted in any part of the body. Euglena green, like unicellular algae, forms organic substances in the light. When there is a lack of light, it feeds on dissolved in water organic substances.
Breath. Free-living protozoa breathe oxygen dissolved in water, absorbing it over the entire surface of the body. Once in the cytoplasm, oxygen oxidizes complex organic substances, turning them into water, carbon dioxide and some other compounds. At the same time, the energy necessary for the functioning of the body is released. Carbon dioxide, formed during the respiration process, is removed through the surface of the body.
Irritability. Single-celled animals respond to light, temperature, various substances and other stimuli. The common amoeba, for example, moves from the light to a shaded place (negative reaction to light), and green euglena swims towards the light (positive reaction to light). The ability of organisms to respond to stimuli is called irritability. Thanks to this property, single-celled animals avoid unfavorable conditions and find food.
Reproduction of sarcodae and flagellates occurs by fission. The maternal individual gives rise to two daughters, which, when favorable conditions lives grow quickly, and within a day their division occurs.
Saving at unfavorable conditions life. When the water temperature drops or the reservoir dries out, a dense shell is formed from cytoplasmic substances on the surface of the amoeba’s body. The body itself becomes rounded, and the animal enters a resting state called a cyst (from the Greek “cystis” - bubble). In this state, amoebas not only survive under unfavorable living conditions, but also disperse with the help of wind and animals. Many sarcodaceae and flagellates turn into cysts, including amoeba dysenteria, Euglena green, Giardia and trypanosomes.
Type of ciliate
Habitats, structure and lifestyle.
The type of ciliates includes slippers, bursaria, geese, and souvoiki. These and most other ciliates live in fresh water bodies with decaying organic residues (their name comes from the Greek “infusion” - infusion). Their body shape is fusiform (slippers), barrel-shaped (bursaria), bell-shaped (trumpets).
The body of ciliates is covered with rows of cilia, with the help of which they move. There are ciliates, for example suvoyki, leading sedentary image life. They are attached to underwater objects by a contractile stalk.
Ciliates have a more complex structure compared to other protozoa. They have a large and small (or small) nuclei, a cellular mouth and pharynx, a perioral cavity, permanent place removing undigested food residues - powder. Contractile vacuoles of ciliates consist of vacuoles themselves and afferent tubules.
Nutrition. Most ciliates feed on various organic debris, bacteria and unicellular algae. Food enters the preoral cavity due to the coordinated vibration of the surrounding cilia, and then through the mouth and pharynx into the cytoplasm (into the resulting digestive vacuole). Undigested food remains are removed through powder.
Respiration and excretion in ciliates occur in the same way as in sarcodidae and flagellates, across the entire surface of the body.
Irritability. In response to the action of light, temperature and other stimuli, ciliates move towards them or towards them. reverse side(positive and negative taxis - movements).
Reproduction and preservation under unfavorable conditions in ciliates occur essentially in the same way as in sarcodidae and flagellates.
The role of unicellular organisms in human life and nature
Protozoa are a source of food for other animals. In the seas and fresh waters, protozoa, primarily ciliates and flagellates, serve as food for small multicellular animals. Worms, mollusks, small crustaceans, as well as the fry of many fish feed primarily on single-celled organisms. These small multicellular organisms, in turn, feed on other, larger organisms. The largest animal that ever lived on Earth is the blue whale, like all the others baleen whales, feeds on very small crustaceans that inhabit the oceans. And these crustaceans feed on single-celled organisms. Ultimately, whales depend on single-celled animals and plants for their existence. Protozoa are participants in the formation of rocks. Examining a crushed piece of ordinary writing chalk under a microscope, you can see that it consists mainly of the smallest shells of some animals. Marine protozoa (rhizopods and radiolarians) play very important role in the formation of marine sedimentary rocks. Over many tens of millions of years, their microscopically small mineral skeletons settled to the bottom and formed thick deposits. In ancient geological epochs, during the mountain-building process, the seabed became dry land. Limestones, chalk and some other dangerous rocks consist largely of the remains of the skeletons of marine protozoa. Limestone has long been of great practical importance as a building material. protozoan remains play an important role in determining age different layers earth's crust and finding oil-bearing layers.
The fight against water pollution is the most important state task. Protozoa are an indicator of the degree of pollution of fresh water bodies. Each type of protozoan animal requires certain conditions to exist. Some protozoa live only in clean water containing a lot of dissolved air and not polluted by waste from factories and factories; others are adapted to life in water bodies of moderate pollution. Finally, there are protozoa that can live in very polluted, wastewater. Thus, the presence of a certain species of protozoa in a reservoir makes it possible to judge the degree of its pollution.
So, protozoa are of great importance in nature and in human life. Some of them are not only useful, but also necessary; others, on the contrary, are dangerous.
Items:
The fight against these numerous and dangerous protozoal diseases requires a detailed study of the biology of pathogens and their development cycles.
Of some practical interest are free-living protozoa. Different types they are confined to a specific complex external conditions, in particular to various chemical composition water.
Certain types of protozoa live at varying degrees pollution of fresh waters with organic substances. Therefore, by the species composition of protozoa one can judge the properties of the water of a reservoir. These features of protozoa are used for sanitary and hygienic purposes in the so-called biological analysis of water.
In the general cycle of substances in nature protozoa play a prominent role. In bodies of water, many of them are energetic eaters of bacteria and other microorganisms. At the same time, they themselves serve as food for larger animal organisms. In particular, the fry of many fish species hatching from the eggs at the very initial stages of their lives feed mainly on protozoa.
The type of protozoa is geologically very ancient. Those species of protozoa that had a mineral skeleton (foraminifera, radiolarians) are well preserved in the fossil state. Their fossil remains are known from the most ancient Lower Cambrian deposits.
Marine protozoa - rhizopods and radiolarians - played and continue to play a very significant role in the formation of marine sedimentary rocks. Over the course of many millions and tens of millions of years, microscopically small mineral skeletons of protozoa, after the death of animals, sank to the bottom, forming thick marine sediments here. When the relief of the earth's crust changed, during mining processes in past geological eras, the seabed became dry land. Marine sediments turned into sedimentary rocks. Many of them, such as some limestones, chalk deposits, etc., largely consist of the remains of the skeletons of marine protozoa. Because of this, the study of paleontological remains of protozoa plays a large role in determining the age of different layers of the earth's crust and, therefore, is of significant importance in geological exploration, in particular in mineral exploration.
Loading...
