§7. Type Flatworms (Classes Ciliated, Flukes, Tapeworms)

Basic classes, structure, nutrition and reproduction. Radial symmetry in the organization of coelenterates in connection with their lifestyle. Metagenesis in hydroid and scyphoid polyps. The importance of movement in the origin of the muscular and nervous systems with sensory organs in jellyfish. Coral polyps, distribution and biological significance. Ctenophores are classified as a separate type). Phylogeny of coelenterates.

REFERENCES: 2, p. 66-84.

Self-test questions

1. Describe coelenterates as multicellular animals.

Why are animals of this type called coelenterates?

What classes is the type of coelenterates divided into?

Lifestyle of coelenterates (feeding, reproduction, development, ability to regenerate, etc.).

The importance of coelenterates in the general evolution of many cellular animals.

Flatworms

General characteristics and division into main classes.

Ciliated worms Morphology and phylogeny of ciliated worms. The origin of bilateral (bilateral) symmetry in the organization of worms and its significance in the evolution of animals.

Flukes (trematodes). (Monogeneas are classified as a separate type).

Reproduction, development with alternation of generations and change of hosts. The relationship between ontogeny and phylogeny in flukes. The main representatives of trematodes, their development cycles and the diseases they cause in domestic animals and humans. Fighting flukes.

Tapeworms (cestodes). Their structure, reproduction and development (ontogenesis), fertility. Tapeworms and tapeworms, their most important representatives and development cycles. Tapeworms as causative agents of invasive diseases in animals and humans. Fight against cestodes. The significance of the works of K. I. Scriabin

Roundworms

General characteristics and division into main classes: nematodes.

Annelids

Ringworms are like higher worms. Metamerism as the main feature of annelid organization. The origin of the secondary body cavity, the circulatory system and their significance in evolution. Development and structure of the ganglion nervous system of annelids. Main classes annelids. Polychaetes. Structural features and lifestyle of polychaetes (polychaetes). Their importance in fish nutrition. Oligochaetes (oligochaetes). The role of annelids in soil formation and its fertility.

Phylogeny of annelids and their significance in the evolution of invertebrates. The role of Russian scientists in the history of the study of annelids. (I. I. Mechnikov, A. O. Kovalevsky, P. P. Ivanov)

REFERENCES: 2, p. 327-351.

Self-test questions

Classification of worms into separate types (flat, round and annelid worms).

List the main features of the differences (according to organ systems) between the types of flat, round and annelid worms.

Origin and connection various types worms with other groups of invertebrates (flat worms with coelenterates, the relationship of annelids with arthropods, etc.).

Give general characteristics and classification of flatworms.

Describe the structure, reproduction and development of flukes (Fasciola hepatica), tapeworms (wide tapeworm, pork and bovine tapeworms) and echinococcus.

Give a general description and classification of roundworms.

Describe the structure, nutrition, reproduction and development of roundworms using the example of the horse roundworm.

Give a general description and classification of annelids.

Describe the structure and biology of ringlets using the example of an earthworm.

Answers to school textbooks

Structural features flatworms:

The body is elongated and flattened in the dorsal direction, the anterior and posterior ends are clearly distinguishable;

They have bilateral symmetry, which allows for more active movements than in radially symmetrical animals (coelenterates);

There are four types of tissues: integumentary, connective, nervous and muscle;

The body wall is a skin-muscular sac formed by a single-layer ectodermal epithelium and muscles lying in three layers (outer - circular muscles, the next, deeper located - longitudinal, deepest layer - diagonal muscles);

Inside the skin-muscle sac there is loose tissue - parenchyma, which contains all the internal organs;

The digestive system is blind and does not have an anus;

Nervous system consists of two nerve nodes in the front part of the body and longitudinal cords extending from them, connected by jumpers;

The excretory system is represented by branched tubules, starting in the parenchyma with stellate cells that have a cavity with a bunch of cilia located in it; vibrations of the cilia cause a flow of fluid containing metabolic products, directing it into the tubules that communicate with external environment excretory openings;

The reproductive system is hermaphroditic, consists of gonads and complex system ducts that serve to excrete germ cells;

2. What sense organs do flatworms have?

Sense organs are usually represented by individual skin cilia - processes of sensory nerve cells. Some free-living representatives of the type, in the process of adaptation to living conditions, acquired primitive organs of vision - photosensitive pigment eyes and organs of balance.

3. What is parenchyma?

Parenchyma is loose connective tissue that fills the spaces between organs. Functions of parenchyma:

1) supporting;

2) storage of nutrients;

3) participation in metabolism and digestion.

In the absence of food, the parenchyma is depleted.

4. How does the nervous system of flatworms work?

The nervous system is represented by two nerve nodes located at the anterior end of the body - the cerebral ganglia and the nerve trunks extending from them, connected by jumpers, i.e., in flatworms, the nervous system is of the scalene type.

5. What are the structural features of the excretory system of flatworms?

6. How does the excretory system of flatworms work?

The parenchyma contains stellate cells that secrete water and metabolic products into the lumen of the tubules. Stellate cells have a bunch of cilia in the recess, which continuously vibrates and drives fluid out through special tubules. The tubules unite into tubes and form pores on the surface of the body. These excretory organs also regulate osmotic pressure, which is why flatworms are common in fresh waters.

7. What kind of life do eyelash worms lead?

Ciliated worms include free-living marine or freshwater worms (milk planaria, black planaria, many-eyed worms), as well as terrestrial ones. As a rule, eyelash worms are predators. They eat many protozoa (ciliates, rhizomes, flagellates), nematodes, small crustaceans, mosquito larvae - often larger animals than themselves.

8. What structural features of flukes are associated with their lifestyle?

Dense protective shell covering the body;

Two suckers for attachment to host tissues;

Hermaphroditism; high fertility;

Simplified sense organs.

9. Describe the development of the fluke.

An adult (sexually mature) individual of the liver fluke lives in the liver of large herbivorous mammals and humans, feeds mainly on bile, as well as blood and liver cells, sometimes causing the death of the main host.

10. Who is called the intermediate host? Who is the intermediate host of the liver fluke?

11. What are the structural features of tapeworms?

Structural features of tapeworms:

Ribbon-shaped body, consisting of a head, neck and several thousand segments, which increase in size towards the end of the body;

On the head there are organs of attachment to the walls of the host’s intestine (suction cups, suction slits, hooks);

Each segment contains a hermaphroditic reproductive system;

The last segments are filled with fertilized eggs, these segments are torn off and brought out;

There is no digestive system, food absorption occurs over the entire surface of the body;

The nervous system is formed by the head ganglion, from which nerve trunks run along the body.

12. What is finna?

Finna is one of the stages of tapeworm development. It is a bubble filled with liquid, in the cavity of which there is a formed worm head with four suckers.

Finna enters the human intestine with uncooked or undercooked meat, Finna attaches to the intestinal wall, and the growth of a worm begins, poisoning the person with metabolic products that cause indigestion and anemia.

13. How does the development of bovine tapeworm occur?

Description methodological development

1. Lesson on the topic:

Type Flatworms. White planaria. (using digital communication center and ICT tools)

2. Combined lesson. In addition to the outline, there is a presentation of the lesson with expressed stages of the lesson.

This lesson uses handouts, a crossword puzzle, video clips and audio clips. In addition, the questions, crossword puzzle and tables used during the lesson are provided with answers using hyperlinks. Thanks to this, the lesson becomes very detailed and easy to use, both for the teacher and the student.

3. Subject - biology 7th grade. Animals.

4.For 7th grade students of OU.

5. Class-lesson form of work.

6. Full description development

Lesson on:

Type Flatworms. White planaria.

Tasks:

1. get acquainted with the features of the external and internal structure, lifestyle of free-living flatworms;

2. identify similarities and differences between flatworms and coelenterates;

3. compile general characteristics of the type Flatworms;

4. Get to know new terms: mesoderm, parenchyma, bilateral symmetry; develop concepts: tissue and organ, organ system.

Means of education : Lesson presentation, table “Flatworms”, COR in biology, multimedia-ICT room, handouts.

Main lesson content:

1. General information about flatworms (bilateral symmetry of the body, three-layer structure).

2. Habitats and representatives of free-living flatworms. Variety of flatworms.

3. Features of the external structure of free-living flatworms, determined by their habitat.

4. Features of the internal structure and vital processes.

5. Features more high degree organization in comparison with coelenterates.

During the classes

Updating knowledge

1.What are the similarities between coelenterates and protozoa?

Coelenterates and protozoa have several similar characteristics:

1. Live mainly in aquatic environment a habitat

2.cellular structure

3.heterotrophic nutrition

4. similarity between the processes of breathing and nutrition

5.similarity of the cells of the inner layer with

the structure of protozoa

What is the practical significance of coelenterates?

Coelenterate animals:

1.regulate the number of fish and crustaceans in nature;

2. create coral reefs and associated communities;

3. Coral skeletons are used to make lime, fertilizers, jewelry and jewelry, etc.

4. experimental objects (regeneration, etc.)

5.used as food in Southeast Asian countries (jellyfish in Japan and China)

What are the general characteristics of coelenterates?

1. radial symmetry of the body;

2.two-layer structure;

3.presence of an intestinal cavity;

4.primitive nervous system;

5.presence of stinging cells;

6.heterotrophs, predators;

7.aquatic habitat

8.two life forms: attached and mobile.

Student message (text)

Planarians

Planarians are flatworms (Platodes), which belong to the class of ciliated worms, or turbellarians (Turbellaria), to groupTriclada.

These are small flatworms that are constantly found in freshwater bodies, where they crawl among aquatic plants. Characteristic feature planarians are a layer of tiny cilia covering their body. The mouth opening is located on the ventral side, and the intestine consists of branches with numerous branches and does not have an anus. All planarians are hermaphrodites.

In the northern and middle lane The USSR is very commonmilky white planaria (Dendrocoelumlacteum), the largest among the others (up to 3 cm), with a completely white body, through which the dark branched intestine is clearly visible (Fig. 171). A pair of eyes can be distinguished on the head.

Even more common everywhere in stagnant bodies of water is much smallerbrown planaria (Planariatorva) brown in color with a rounded head end, which also has two eyes. Black planaria is common ( Polycelisnigra) with a rounded head end, along the edge of which sits a row of eyes. Finally, in flowing waters livesmourning planaria (Planarialugubris), also dark in color, but distinguished by its characteristic head end, which looks like an obtuse triangle.

When catching planaria, you should catch more aquatic plants in the net, which are subject to careful inspection. However, planarians are often overlooked by beginners due to their small size, dull coloring and slow movements. The exception is the milky white planaria, which usually catches the eye with its color. Most often, planaria can be found on the underside of floating water lily leaves.

Crawling underwater on solid objects, the worm moves forward extremely smoothly, slowly and evenly, as if swimming, without any visible effort. The reason for this peculiar movement is the cilia covering the animal’s body, which are invisible to the naked eye. Planarians secrete an abundant mucous mass that envelops the objects on which they sit. When moving, the cilia rest against this mucous band, pushing the animal's body forward. Small species can, in addition, swim freely with the help of oar-shaped blows of the cilia on the water.

Planaria feed on small aquatic animals and are quite active predators. They do not refuse carrion either. In captivity they eat and White bread. The mouth is located on the ventral side and leads into a movable, extensible pharynx, which can protrude outward like a tube. The intestine has an extremely branched shape, which can be especially clearly observed in the milky-white planaria if you look at it through a magnifying glass in transmitted light.

Planaria reproduce by eggs, which are enclosed in a round or oval cocoon, slightly larger than a pinhead, and brownish in color. Such cocoons are attached to underwater objects, and in some species they are attached to the substrate on special stalks.

4. Identification of similarities and differences between flatworms and coelenterates.

Students fill out the table in their notebook " Comparative characteristics coelenterates and flatworms” and draw a conclusion from it.

They reveal features of a higher degree of organization of organisms in comparison with Coelenterates.

5.Features of the internal structure and life processes. The appearance of tissues and organs. Sexual reproduction. Regeneration of planaria.

(Teacher's story with elements of conversation based on presentation slides)

3. Consolidation of knowledge

Independent work students according to the table " Internal structure white planaria."

Estimated completed table:

4 Homework

1.Study §15 of the textbook, answer the questions orally after §.

2.Write down the definitions in a notebook: “hermaphrodite”, “parenchyma”, “skin-muscle sac”.

5. Generalization of knowledge on the topic of the lesson:

Structural features of flatworms. Complication of their structure compared to coelenterates.

Formulate a conclusion with students (reflected in the presentation). Curriculum 2 foreign language 3 National history 17

People sometimes neglect helminthic infestation as an unpleasant, but quite easily tolerated ailment. Accordingly, their beliefs do not encourage them to be extremely careful when coming into contact with any kind of dirt, poorly processed food, or contact with pets.

Such criminal negligence has its sad results. Worms are capable of killing their prey, apart from pain and organ damage. The most dangerous are helminths that feed on blood and useful substances inside a person.

The malarial plasmodium destroys blood cells and can lead to death in the victim.

Consequences of infection:

• development of malignant tumors;
• immunity weakens;
• Metabolism is disrupted.

Manifestations of helminthic infestation are very different from each other. But they also have common symptoms:

• muscle pain that weakens and swells;
• joints hurt, although they were not injured;
• the liver and spleen increase in size;
• skin rash;
• heat.

You can add to them:

Worms sometimes lead the body of an infected person to such a state that full-fledged healthy life, even after their removal, is no longer possible. Therefore, if you discover any of the symptoms, you should immediately consult a doctor.

Photos of worms that can live in you

Symptoms of their presence are not immediately and not clearly expressed in everyone. A long stay of worms will lead the body to chronic diseases. It is believed that many diseases begin with worms. Before you begin treatment, you should first recognize your inner enemy so as not to fight blindly.

Worms that settle in humans are divided into types:

• roundworms;
• tapeworms;
• flukes.

Below are photos of worms in the human body:

Thanks to such materials smart people more armed to protect themselves and their loved ones. But no one should do anything themselves in the destruction of uninvited “guests”.

Useful video

Below we suggest you look documentary dedicated to the symptoms and infection of worms:

The vast majority of helminths have a negative effect on the general well-being and health of a person, provoking the development of very serious diseases. Keeping this in mind, when the first signs of illness appear that do not go away with treatment of a cold or skin rash with headaches, you should consult a doctor for an appointment for diagnosis.

How to prevent helminthic infestation? Do you need to constantly limit yourself to one or another vacation, literally “squeezing” your life in a vice by observing complex postulates?

But everyone needs to start with themselves, because all modern achievements mean nothing if you simply neglect personal hygiene and preventive measures for those family members who live in our home. Being attentive to your health, detecting it in time (if infection has occurred), starting treatment competently and in a timely manner - all this will help prevent a big disaster on a personal level and the spread of the disease in your environment.

2.What structural features and lifestyle allow us to divide the type of flatworms into classes.
3.Why do tapeworms lack digestive organs?

1. In contrast to the radial symmetry of coelenterates, such symmetry is called bilateral. (Bilateral or bilateral symmetry first appears in this type of animal).
Unlike coelenterates, the nervous system of flatworms is not diffuse. It consists of the head nerve ganglion and several longitudinal nerve trunks, of which the most developed are the 2 lateral or abdominal trunks.


2. The body of Coelenterates looks like a sac open at one end, surrounded by tentacles. The body cavity is gastric (represented by a blindly closed primary intestine).


5. A variety of types of gastrulation - the formation of a two-layer embryo (gastrula).

Character traits coelenterates:
1. The ectoderm contains various types of stinging cells.
2. The body of Coelenterates looks like a sac open at one end, surrounded by tentacles. The body cavity is gastric (represented by a blindly closed primary intestine).
3. The respiratory, circulatory and excretory systems are absent.
4. There are no permanent sex glands (gonads); their functions are performed by single (interstitial) cells, from which both eggs and sperm are formed.
5. A variety of types of gastrulation - the formation of a two-layer embryo (gastrula).
6. Metagenesis is widespread - alternation of sexual and asexual generations. The sexual generation is usually represented by the jellyfish stage, and the asexual generation by the polyp stage.

Characteristic features of the Flatworm type:
1. The integument of the body and the underlying layers of muscles form a musculocutaneous sac.
2. The spaces between organs are filled with connective tissue parenchyma.
3. The digestive system consists of two sections: the foregut and the blindly closed midgut.
4. Nervous system – ladder (orthogonal) type.
5. Protonephridial type excretory system.
6. Hermaphroditism. Fertilization is internal.

In contrast to the radial symmetry of coelenterates, this symmetry is called bilateral. (Bilateral or bilateral symmetry first appears in this type of animal).
Also, unlike coelenterates, in the process of development from a fertilized egg, they form not two, but three layers of cells: the outer - ectoderm, the inner - endoderm, and the intermediate - mesoderm, from which various organ systems subsequently develop.
Unlike coelenterates, the nervous system of flatworms is not diffuse. It consists of the head nerve ganglion and several longitudinal nerve trunks, of which the most developed are the 2 lateral or abdominal trunks.

Answer