Round ringed. Flat, round and annelid worms

07.01.2024

general characteristics

Ringed animals got their name because of their elongated body, divided inside into segments that form rings when cut. They move with the help of special outgrowths on their body. There are sensitive antennae, organs of hearing, smell, and eyes with ciliary pits on the head.

The outside of the body is covered with a cuticle; inside, each segment is filled with liquid. When damaged, the worm loses most of its segments and quickly regenerates. The oral opening is located in the first section, on the side of the abdominal cavity. Some species have jaws. The circulatory system is closed, there is no heart. The ventral and dorsal are connected by rings. The blood contains hemoglobin, which allows individuals to survive.

There are no respiratory organs, gas exchange occurs through the skin. Among the species there are hermaphrodites, dioecious individuals, reproduction occurs in various forms. Annelids are predators, herbivores, and there have been cases of cannibalism.

Kinds

Annelids are divided into classes:

Polychaetes. The most common species lives in the sea. They have a well-defined head section and the presence of limbs. They have a serpentine body, gills, and actively swim.
Oligochaetes. They live on land, the body has bristles for burrowing movements. The head section is not expressed, there are no eyes or appendages. The most common are earthworms.
Leeches. Representatives of the species are predators, feeding on the blood of people, animals, and fish. The mouth is equipped with plates or a proboscis for cutting through the skin, the pharynx plays the role of a pump when sucking blood. Some species secrete poison.
Echiurids. The rarest species are filter feeders. They live in the deep sea, sandy burrows. They have a proboscis, which they periodically discard and grow again.

Habitats

Ringed worms live in seas, reservoirs, and soil. The seas are home to most of the worms that fish feed on. Blood-sucking predators, leeches, live in fresh water bodies. Earthworms live in the soil and have a beneficial effect on soil formation. Their number can be 600 individuals per square meter.

Danger to humans

Leeches cause hirudinosis. They attach to the skin and penetrate internal organs, which leads to suffocation.

general characteristics

Bilateral symmetry of the body of roundworms in cross section has a round shape, hence the names. Nematodes do not have organs of locomotion, and they move by contracting longitudinal muscles.

The internal organs are located in the primary cavity, the space between them is filled with hydrolymph, which performs transport functions. There is no circulatory system, gas exchange is carried out by the body membrane. Digestion is represented by the anterior, middle, and posterior sections. The anterior one has the esophagus, the oral cavity, the middle one processes food, and is excreted from the posterior section.

Nematodes have organs of smell, touch, and some organs of vision. The nervous system is represented by a nerve ring and six stem nerves. The majority of the representatives are dioecious; fertilization occurs within the females.

Kinds

Roundworms are divided into several classes, but the largest is the class of nematodes. Their numbers about 40,000 species, the most common:

Roundworms. They have the shape of a cylinder and reach 20-40 cm. They cause the disease ascariasis.
Pinworms. They are white in color, small in shape, and the length of the pinworm can reach 10 cm. They cause the disease enterobiasis, which most often affects children.
Whipworm. They feed on blood, the length of the worm is 45-55 mm. They cause a difficult to cure disease, trichuriasis.
Trichinella. They live only in one owner, since they are not adapted to the external environment. Infection with Trichinella can lead to psychomotor retardation.
Krivogolovka. They are pink in color and length is about 18 mm. Crooked heads stick to mucous organs, sucking blood from them. The disease is caused by hookworm.

Habitats

They live almost everywhere; they can be found in ponds, algae, sand, and growths on trees. They feed on bacteria and plant sap. Some types of roundworms live in forests in moss and soil. When conditions for life are not favorable enough, representatives of this species fall into suspended animation and successfully wait out bad times.

Lutokhina Irina Petrovna

Biology teacher, MKOU Secondary School No. 2, Revda

Test and general lesson on the topic

“Flat, Round and Annelid Worms” (Slide 1)

Lesson objectives:

Educational:

Summarize knowledge about the structure and life activity of flat, round and annelid worms, establish their relationships with their habitat;
To expand students’ knowledge about the applied significance of animals in nature, the meaning and role in nature and human life ( slide 2);

Educational:

To form a cognitive interest in biology; draw conclusions, solve problematic issues, compare, analyze, speak publicly, work on a computer;
Formation of critical thinking;

Educational:

Improve the ability to compare, establish connections between theory and practice, and the ability to use the language of biology;
Foster a caring attitude towards nature;
Responsible attitude towards completing assigned tasks.

Equipment: Pentium III class computer, multimedia projector, presentation.

Lesson type– lesson-game

Methods:

Methods of developing interest in learning (storytelling, educational discussions, methods of emotional stimulation);

Methods of organizing and implementing educational activities and operations (story, demonstrations, completing tasks and exercises, analysis and comparison of educational material);

Methods of self-management of educational activities (independent work with text, supporting notes);

Methods of control and self-control (survey during the lesson, testing, solving biological problems, anagrams, etc.).

Interdisciplinary connections: computer science and ICT, ecology and history.

During the classes

I. Organizational moment ( greeting students, marking absentees);

II.Updating knowledge(combined survey)

Guys! Now you are sitting on teams (2). I invite one representative from each group to draw 1 token from the bag, on which it will be written which type of worm you will give a general description of. Draw of lots. Repeat for 1 – 2 minutes. There are pieces of paper on your tables with a table on them. You fill it out collectively, because... you work in groups and then we review everything together.

General characteristics of flatworms;

General characteristics of roundworms;

Exercise 1

Filling out the table:

General characteristics of worms (Slide 3)

Characteristic	Type Flatworms	Type Roundworms	Type Annelids
1. Representatives
2. Symmetry
3. Number
4. Skin-muscle bag
5. Digestive system

7. Nervous system
8. Excretory system
9. Reproductive system
10. Habitat

Filling out the table correctly (answer)

Characteristic	Type Flatworms	Type Roundworms	Type Annelids
1. Representatives	White planaria, tapeworm, liver fluke	Human roundworm, pinworm	Earthworm, Nereid
2. Symmetry	Double-sided	Double-sided	Double-sided
3. Number	12500 species	1 million species	9 thousand species
4. Skin-muscle bag	Longitudinal, circular and oblique muscles	Longitudinal muscles	Longitudinal and circular muscles
5. Digestive system	Mouth-pharynx-intestines	Mouth – pharynx – intestines – anus	Mouth-pharynx-esophagus – crop – stomach – intestines – anus
6. Circulatory and respiratory systems	None	Absent	Closed, 2 vessels, “5 hearts”
7. Nervous system	Head nerve ganglia and longitudinal nerve trunks connected by transverse bridges	Absent	Nerve cord and peripharyngeal ring
8. Excretory system	Branched tubules, flame cells, longitudinal channels	Through body fluids	Through the tubes in the joints
9. Reproductive system	Hermaphrodite Testes, vas deferens, copulatory organ. Paired ovaries, oviducts, copulatory bursa	Dioecious, up to 200 thousand eggs per day	Hermaphrodite
10. Habitat			Water, soil

The time for repetition is up, let's listen to the general characteristics for the type of flatworms that group No. 1 prepared (student's answer).

The next type is roundworms. And again the general characteristics that the guys from group No. 2 prepared (student’s answer).

And the last type is annelids. First, let's listen to the general characteristics of the guys in group No. 3 (the characteristics are given by the student).

Task 2

And now we will complete several interesting tasks in the order in which we completed the worms. And we will start with the “Flatworms” type

Slide 4

Crossword puzzle on the topic “Flatworms”

Questions (asked orally by the teacher):

Vertically: 1. Fusion of male and female gametes. 2. Vesicular stage of the bovine tapeworm. 3. Cluster of nerve cells - nerve... 4. Liver... 5. Loose connective tissue of flatworms. 9. Packing eggs of a free-living flatworm. 10. Part of the hydra’s body with which it attaches to the substrate. 12. Coelenterate, having a hard skeleton. 15. Outer layer of the skin-muscle sac.

Horizontally: 6. Lentets. 7. Capsule. 8. Ovum. 11. Predator. 13. Hair. 14. Head. 16. Atoll. 17. Planaria.

Vertically: 1. Fertilization. 2. Finn. 3. Knot. 4. Fluke. 5. Parenchyma. 9. Cocoon. 10. Sole. 12. Coral. 15. Leather.

Task 3

The pictures are mixed up. You need to put them in the correct order.

1st student: Make a diagram of the “Development cycle of the liver fluke” from the illustrations.

Slide 5(working with models)

Rice. 2. Liver fluke eggs

Rice. 3. Free-swimming larva

Rice. 4. Development of the larva in the body of the small pond snail

Rice. 5. Larva with a tail

Rice. 6. Cyst

Slide 6(on the interactive whiteboard)

2nd student: Make a diagram of the “Bovine tapeworm development cycle” from the illustrations.

Rice. 8. Segments with eggs of bovine tapeworm

Rice. 9. Cow with larvae

Rice. 10. Larva with chitinous hooks

Rice. 11. Finn in the muscles of a cow

Task 4

Slide 7

Indicate the correct statements with a “+”:

Answers: 8

Task 5

Now we will solve several biological problems:

Slide 8

The sense organs and nervous system of the pork and bovine tapeworm are poorly developed, and the digestive organs are completely absent. What do these signs indicate?

In the 19th century, the St. Petersburg doctor Weiss noticed that children who were prescribed to eat raw meat for medicinal purposes were often found to have tapeworms afterwards. Explain why?

Sometimes the guys eat sorrel from damp meadows, wild onions, or just chew grass. Explain why this cannot be done?

Let's move on to completing tasks like “Roundworms”

Task 6

Biological lotto (questions and answers). If everything is done correctly, you get a picture on the reverse side

Slide 9

Name of the class of roundworms?	A layer of granular epithelial cells lying under a dense cuticle?	What surrounds the mouth opening of roundworms?
Organs of touch and smell of roundworms?		A hole at the rear end of a roundworm's body?

Slide 10

Answers

Nematodes	Hypodermis
	Human roundworm	Anal hole

Task 7

"Mute Drawing"

The board shows different representatives of roundworms. Your task is to determine who is who?

Slide 11

Drawings

Ascaridamore nematode (Statoria) pinworm

Slide 12

Physical education minute

Slide 13

C. Darwin

Task 8

Slide 14

"Who is who?"

All teams must determine who is who and write the answers on a piece of paper.

Action – 1.(Characters are classified)

The phone is ringing. Tubifex picks up the phone.

Peskozhil. Hello! Hello! It's hard to hear! Is this Quiet? Quiet? Who's on the line?

Tubifex. Hello! Who's speaking? Murmansk? Barencevo sea? Limanodrilnevsky is on the line.

Peskozhil. Hello, ringed relative! How are you doing, little bristlecone, are you filtering everything?

Tubifex. I filter it little by little, but what can you do? People are littering the river more and more, and someone needs to clean it up. Well, how are things going with your housing?

Peskozhil. Yes, it's fine now. Although, of course, there was trouble... And you need to find a free place, and not bare sand, but with silt. And get rid of your competitors - everyone is trying to get into your territory. And you’ll put in a lot of work until you dig a new hole - wow! We need it to have two exits, reinforced inside, and cover one exit with sand for camouflage.

Tubifex. Yes, I have an easier time with this. I buried my head in the silt, put my back end out so that I had something to breathe - and live for myself, purify the water.

Peskozhil. How did you bury your head? What to breathe with?

Tubifex. Well, my blood is like that of humans - with hemoglobin, red, so I can live in dirty water, and I breathe, like most worms, - with the entire surface of the body, i.e. the rear part, which rises above the ground. But this is just causing trouble...

Peskozhil. What is it?

Tubifex. Can you imagine, whoever is not too lazy, everyone clings to this end, but it would be fine if they just took a bite (it will grow again anyway), so they are increasingly trying to pull me out of the hole entirely. And if any fisherman or aquarist notices us, he will certainly come running with a net and let us pull us out of the ground, for the fishes to eat.

Peskozhil. And they bothered me with this. You need to be on your guard all the time. If you gape a little, if you show the tip of the body from the mink, they will immediately chop it off. Well, at least I’ll regenerate some more, I’ll wait an hour and let’s recover again.

Tubifex. Yes, by this miracle nature did not offend us.

Peskozhil. Yes, I want to ask you goodbye: why did they call you that? Well, I understand. And you?

Tubifex. Yes, all because of the end of it, which sticks out. Do I need to protect him with something? Well, I strengthen it - it becomes as strong as a tube. Listen, relative. It's good that you called. I have business for you.

Peskozhil. Which?

Tubifex. Yes, I’m tired of this insipid life of ours, I want to come and visit you. Can?

Peskozhil. Where are you going? Where will you live? I explained to you everything about my hole; mine, like all of us, has a single room. You already know how many of us are born in the Barents Sea on every square meter! Every centimeter counts. And here you are about to fall on my head. And don't think!

Tubifex. (sad) So that means it’s impossible? I need very little space. OK. Call me if anything happens.

Action – 2

Leech(untied). Hey kid. Who are you?

Tubifex. I am Limnodril Nevsky.

Leech(looking closely). Also a worm, or what?

Tubifex. Exactly so, sir, ringed.

I've been living for about six years

In calm, quiet ponds,

Eyes, suckers, everything is with me

And they serve me well.

(But the most important thing is the jaws. Three pairs!)

Tubifex. As for the monument, this is too much.

Leech(dismissively). Do you think I'm asking too much? Nothing like this! And who has saved people from high blood pressure over the centuries? From blood clots? But who knows what else? They are still studying me! Believe it or not, sometimes for two years there is not a single drop of blood in your mouth.

Tubifex. It won't take long to die like that.

Leech. It's okay, we're familiar. But if I have lunch, I can drink so much blood at once that I don’t have to eat for another year.

Tubifex. Like this?

Leech. And so. Blood can be stored in my stomach for a long time; special bacteria live there. Also, people noticed that after my bite the blood flowed out of the wound for a long time without clotting. They became interested in this and found a substance in my saliva, they named it hirudin, after me, that is. So, it turned out that this substance helps people treat thrombosis, which is the name of the disease when the blood clots too much and a person can even die from blockage of blood vessels. And here we come to the rescue.

Tubifex. Yes, what a celebrity you are!

Leech. Of course! Okay, I'm stuck here with you. I swam further.

Task 9

“Once upon a time there lived a Little Worm”...

The teacher reads a poem. It is necessary to determine which ringed worm is being discussed in this poem and justify your answer.

Slide 15

There lived a little worm in the world,

He was terribly lonely

I wandered alone all year round,

I only ate once a year...

The worm is a daring swimmer,

Despite being short in stature.

He was able to change color more than once -

For protection, without embellishment.

No bristles for movement

Only victims have no salvation -

There are suckers, hirudin.

Who is this gentleman?

Slide 16

They live in underground silence,

Moving quietly, rustling.

They eat leaves, fruitless litter,

They swallow it slowly.

They are brown

Several “hearts” drive blood.

Their body consists of many

Interlocking rings.

Everything that is eaten will soon become

Food for future flowers.

They are friends for the harvest

And food for both birds and moles.

Fish and chickens love them,

The gardener, the fisherman are glad to see them,

Well, tell me, guys, who became

The hero of these poems?

Slide 17

3. At the bottom of the seas, where there is a lot of silt,

Friends live buried in the ground.

Their body is a little long,

Sits in a hole, upward - “pipe”

Years of life pass in labor

The “pillows” are red at the bottom.

The oxygen carrier in the blood is

Hemoglobin, like in you.

They swallow natural sludge,

Saving water from rot.

Tell me, experts of nature,

What kind of useful “friends” are they?

Task 10

Slide 18

Who hid...?

Slide 19

There is a rectangle in front of you. Your task is to find in it the names of various representatives of worms (on the interactive board).

planaria (type of flatworms, class ciliated),

tapeworm (type flatworms, class tapeworms or cestodes),

Ascaris (type of roundworms, class of nematodes),

pinworm (type roundworms, class nematodes),

sandworm (type annelids, class oligochaetes),

tubifex (type annelids, class oligochaetes),

many-eyed (type of flatworms, class ciliated).

Ligulidae (type flatworms, class tapeworms),

leech (type annelids, class oligochaetes),

Nereis (type annelids, class polychaetes).

Task 11

Test on the topic “Flat, round and annelid worms” (each task has only 1 correct answer):

Slide 20

1. The body has bilateral symmetry:

A) jellyfish
B) sea anemone
B) white planaria
D) hydra.

Slide 21

2. The digestive system of planaria is formed by:

A) thin branched tubules
B) testes and ovaries
B) nerve trunks
D) mouth, pharynx, intestines.

Slide 22

3. Planaria is a hermaphrodite, because

A) one individual produces female and male reproductive cells
B) one individual has female and the other has male reproductive cells
B) it does not reproduce sexually
D) it reproduces vegetatively.

Slide 23

A) flattened body
B) suckers
B) developed digestive system
D) developed sense organs.

Slide 24

A) earthworm
B) bovine tapeworm
B) liver fluke
D) human roundworm.

Slide 25

6. All roundworms:

A) an elongated cylindrical body
B) oblate body
B) the body cavity is filled with fluid
D) no digestive system.

Slide 26

7. All roundworms:

Slide 27

A) you must observe the rules of personal hygiene
B) you can’t work with the ground
C) you can’t drink boiled water
D) you need to eat less vegetables and fruits.

Slide 28

9. Annelids include:

A) white planaria
B) earthworm
B) roundworm
D) bovine tapeworm

Slide 29

10. Mucus covering the body of an earthworm:

A) promotes the absorption of nutrition. substances
B) protects the worm from predators
B) facilitates movement in the soil
D) allows the body to bend.

Slide 30

11. The earthworm’s circulatory system provides:

A) removal of harmful substances
B) digestion of food
B) transport of oxygen and nutrients
D) relationship with the environment

Slide 31

12. An earthworm reproduces:

A) laying eggs
B) disputes
B) budding
D) vegetatively.

Slide 31

13. The role of earthworms in soil formation is that they

A) dissolve rocks
B) crush plant residues, mix the soil
C) absorb mineral salts from the soil
D) compact the soil.

Task 12

Restore the correct order of letters so that you get the name of the animal (worm).

Solving anagrams (work with the class).

Slide 33

a) let's go away

c) adirpaopi
d) ingruid
e) ymestgne
e) archpenmia

Answers: mesoderm, coelom, parapodia, hirudin, segments, parenchyma.

Task 13

Eliminate unnecessary...

Work with the class on the taxonomy of worms (in groups)

Now the names of representatives of various types of worms will appear on the board. Your task is to determine which of the listed animals is superfluous and why, i.e. Tell me, what type is the worm you excluded? We will work in groups. If the group does not know the answer to a question, the turn moves to another group.

Task for group No. 1

Slide 34

White planaria

Ascaris

Liver fluke

Bull tapeworm

Pork tapeworm

Group assignment No. 2

Slide 35

Statetory

Cat fluke

Pile

Pinworm

Ascaris

Task for group No. 3

Slide 36

Tubifex

Earthworm

Peskozhil

Ascaris

Task 14

Slide 37

“I believe it or not”

At this point you should demonstrate your knowledge of the general characteristics of annelids. I read sentences that are simultaneously displayed on a computer monitor, you must consult in a group and decide whether you can or cannot believe this or that judgment.

Annelids have a skin-muscular sac. (Yes).

All annelids live in soil. (No).

The excretory organs of annelids are metanephridia. (Yes).

All annelids are hermaphrodites. (No).

The nervous system of annelids is of the chain type. (Yes).

Annelids have a circulatory system. (Yes).

Most annelids breathe over the entire surface of their body, but some have special skin projections on their parapodia - gills. (Yes).

Annelids are characterized by regeneration. (Yes).

Task 15

Slide 38

Talk about the role of earthworms in nature and human life.

The role of earthworms in nature:

The cycle of substances in nature,

They form humus - humus (the organic part of the soil, rich in nutrients) - “bread” for plants (98% soil nitrogen, 60% phosphorus, 80% potassium and other mineral elements for plant growth),

Link in the food chain

Form soil drainage

Disinfect the soil

Loosen the soil

Create soil ventilation,

Prepare the land for plant growth.

Slide 39

The role of earthworms in human life:

1. Humus (organic) fertilizer.

2. BAS (biologically active substances - essential amino acids, enzymes, vitamins) are used in:

veterinary medicine

pharmacology,

cosmetology,

agriculture,

biotech industries.

3. Food for fish and pets.

4. Protein flour, canned food.

5. Processing of manure and waste.

6. Study of regeneration processes.

Task 16

"Erudite" competition

Solve a problem:

Slide 40

Task No. 1

Meat is an important human food product, but it is consumed only after special cooking. Why is this kind of meat processing necessary?

Slide 41

Problem No. 2

Scientists have established that there is a connection between the number of certain species of mollusks in water bodies, near pastures and helminthic diseases of cattle grazing there.

Explain this dependence.

Slide 42

Problem No. 3

Earthworms live in burrows that they dig in moist soil, and in dry soil they weave into a ball.

What significance does this phenomenon have in the life of earthworms?

Answer: (the formation of a ball of earthworms in dry soil has a protective value; this preserves the moisture of their skin; maintaining skin moisture is necessary for earthworms, since they breathe through the surface of only damp skin).

Task 17

Complete the statement “Structure and vital functions of worms”

Instead of dots, choose the appropriate words, i.e. complete the statements.

Slide 43

The body of the planaria is covered on the outside...

Flukes are held inside the liver ducts by...

The body of tapeworms consists of a large number of...

The musculature of ciliary worms is formed by circular longitudinal and... layers of muscles.

Tapeworms feed on ready-made food digested by the host, absorbing it through...

The intestines of large worms begin with the mouth opening and end...

The nervous system of flatworms consists of a head ganglion, nerve branches and...

Spermatozoa of worms develop in...

Worm eggs develop into...

The organisms in which adult worms live are called...

When an earthworm moves through the soil, it is of great importance...

The movement of blood through the blood vessels of annelids occurs due to contraction and relaxation...

The nervous system of annelids consists of a peripharyngeal nerve ring and...

The assignment is checked by the whole class. Representatives from each group take turns pronouncing completed sentences.

Task 18

"Give me your passport"

A draw is held. Three tokens: flatworms, roundworms, annelids. In accordance with the drawing of lots, the teams complete the task “Whose characteristics” (it is necessary to select from the list only those that characterize these worms).

Worksheet with the task “Whose sign”

Bilateral symmetry

Skin-muscular sac

Ectoderm

Endoderm

Circulatory system

Testes

Stellate cells with cilia

Respiratory system

Secondary cavity

Anal hole

Segments
Neural chain
Peripharyngeal nerve ring
Circular muscles
Longitudinal muscles

Answer: Flatworms: 1,2,3,4,5,7, 8, 10, 13, 14, 18

Roundworms: 1,2,3,4,5,7, 12, 13, 17

Annelids: 1,2,3,4,5, 6, 7, 11, 12, 13, 15, 16, 17, 18

Slide 44

And finally, listen to the poem.

According to their body shape, worms are divided into three types: Flat, Round and Ringed. All worms are three-layered animals. Their tissues and organs develop from three germ layers - ectoderm, endoderm and mesoderm.

Type Flatworms and their characteristics

Type Flatworms unites about 12,500 species. In terms of their organization, they are higher than coelenterates, but among three-layered animals they are the most primitive. These animals can crawl slowly. The most characteristic feature of flatworms is their flattened body, in the shape of a long ribbon.

The figure below shows the structure of a Flatworm using Planaria as an example.

Structure	The body is flattened in the dorsal-abdominal direction, the space between the organs is filled with a special tissue - parenchyma (there is no body cavity)
Coverings of the body	Skin-muscle bag (skin fused with muscle fibers)
Nervous system	Two nerve trunks connected by nerves (“scalenes”)
Sense organs	Ocellus in the front of the body, tactile cells scattered throughout the body
	The digestive system is blindly closed; there is a mouth --> pharynx --> branched intestines
	Whole body surface
Selection	A system of tubules that open outward on the sides of the body
Flatworm Reproduction	Hermaphrodites; sperm mature in the testes, eggs mature in the ovaries; the female lays eggs from which young worms emerge

Variety of Flatworms, their main classes

Type Roundworms and their characteristics

Type Roundworms- a large group of animals with a long, round body in cross-section, which is pointed at the anterior and posterior ends. Roundworms are characterized by the presence of free space inside the body - a primary cavity. It contains internal organs surrounded by abdominal fluid. By washing the cells of the body, it participates in gas exchange and the transfer of substances. The body of roundworms is covered with a durable shell - the cuticle. This group has about 20 thousand species.

The figure below shows the structure of a Roundworm using the Ascaris as an example.

Structure	An elongated cylindrical body, pointed at both ends, round in cross section, is a body cavity
	Skin-muscle bag
Nervous system	Ventral nerve cord
	Mouth (3 hard lips) --> pharynx --> intestinal tube --> anus
	Whole body surface
Selection	Through the surface of the body
Reproduction	Most are dioecious; the female lays eggs from which young worms emerge
Representatives

Type annelids their characteristics

Type Annelids- a group of animals whose representatives have a body divided into segments resembling rings folded one after another. There are about 9 thousand species of annelids. Between the skin-muscular sac and the internal organs they have in general- secondary body cavity filled with fluid.

Structure	The body consists of segments, there is a body cavity
	Leather; muscles - longitudinal and circular
Nervous system	Suprapharyngeal and subpharyngeal ganglia and the ventral nerve cord, from which nerves arise in each segment
	Mouth --> pharynx --> esophagus --> crop --> stomach --> intestines --> anus
	The entire surface of the body; marine animals have special body extensions - gills
Selection	In each segment there is a pair of tubules that open outwards with excretory pores
Reproduction of annelids	Hermaphrodite; the female lays eggs in the cocoon, from which young worms emerge
Manifold	1. Class Malochaetes - live mainly in soil and fresh water bodies, have small setae on each segment (representative - earthworm) 2. Class Polychaetes - live in the seas; have paired outgrowths with bristles on the sides of the body (representative - nereid, sandworm)

_______________

A source of information: Biology in tables and diagrams./ Edition 2, - St. Petersburg: 2004.

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Class-7

Item- biology

The purpose of the lesson: summarize and systematize students’ knowledge on the topic “Flat, Round, Annelid Worms” through game techniques.

Tasks:

Educational: consolidation and deepening of students’ knowledge about the diversity, features of organization, structure, and vital activity of flat, round, and annelid worms.
Educational: development of logical thinking techniques, activation of students’ cognitive activity.
Educational: development of communication skills, a sense of responsibility, formation of a careful attitude towards one’s health.

Lesson type: lesson summary.

Lesson format: a game.

Equipment: PC, multimedia projector, screen, presentation.

During the classes

1. Organizational moment (external and internal readiness of students).

2. Introductory speech by the teacher.

In previous lessons we studied a group of animals called “worms”. What types of worms are included in this group? (Students name the types of flat, round, annelid worms). Today in the lesson we will generalize knowledge about the structure, life processes and significance of worms. We will generalize in the form of an intellectual game “Own Game”.

Rules of the game:

The class is divided into 3 teams. Each team chooses a captain who chooses a question from any section and any difficulty.
30 seconds are given to discuss the answer to the question. For an early answer, the team receives 0.5 points.
If a team does not answer a question or answers incorrectly, the turn goes to the team that raised its hand first.
If a “pig in a poke” appears, the move goes to the next team in order.
The team with the most participants answering the questions receives an additional 2 points.
The right to start the game is determined by drawing lots.

3. Game.(Appendix. Presentation.).

Questions and assignments.

1). Indicate the name of the representative of the phylum Flatworms.

4). The sense organs and nervous system of the pork and bovine tapeworm are poorly developed, and the digestive organs are completely absent. What do these signs indicate?

5). In the 19th century, the St. Petersburg doctor Weiss noticed that children who were prescribed to eat raw meat for medicinal purposes were often found to have tapeworms afterwards. Explain why?

6). Why can’t roundworms and soil nematodes stretch and shorten their bodies?

7). Tapeworms and roundworms live in the same environment - in the small intestine of the host, which contains ready-digested food. However, tapeworms do not have digestive organs, while roundworms have a mouth, pharynx, esophagus and intestines. Why?

8). At the end of the last century, one doctor, in an experiment carried out on himself, found out that larvae and subsequently adult worms do not develop from eggs just laid by a female roundworm and swallowed by a person. How can we explain the results obtained in the experiment?

9). It is known that if you try to pull out an earthworm crawling into its hole, you will tear it apart rather than pull it out. Why?

10). What conclusions can be drawn from the following facts:

earthworms avoid dry soil and always stay in moist soil;

Earthworms crawl out of their burrows onto the soil surface at night or during the day after rain.

eleven). Much is known about the activities of earthworms. For example, scientists believe that some remains of ancient Roman structures ended up underground thanks to the work of earthworms. Explain how this happens?

12). Name the stages of development of the liver fluke.

13). List the organ systems of the milky white planaria.

14). Name the organ system shown. What is its function?

15). What is sexual dimorphism? How does a female roundworm differ from a male?

16). What organ system first appeared in the earthworm?

17). What is regeneration? Can it be attributed to the methods of earthworm reproduction? Explain your answer.

20). Indicate a representative of the type Roundworms (see task 1).

21). Name the representatives of the phylum Annelids. Indicate which class they belong to.

There lived a little worm in the world,
He was terribly lonely
I wandered alone all year round,
I only ate once a year...
The worm is a daring swimmer,
Despite being short in stature.
He was able to change color more than once -
For protection, without embellishment.
No bristles for movement
Only victims have no salvation -
There are suckers, hirudin.
Who is this gentleman?

Answers.

2). The presence of suckers, hooks, enormous fertility, a development cycle with a change of hosts, dense body coverings that are not digested in the host’s body.

3) Enormous fertility is associated with a low probability of eggs entering the body of a new host, and is an adaptation to the preservation of the species.

4) These organisms live in the host’s body, where they are protected from unfavorable conditions and provided with food. Living conditions are constant.

5) Raw meat may contain finns (larvae), the activation of which in the human intestine marks the beginning of the development of an adult worm.

6) The roundworm has only longitudinal muscles, so it can only twist its body. The shortening and elongation of the body is due to the presence of circular muscles.

7) The bovine tapeworm attaches to the intestines and absorbs food over the entire surface of the body. The roundworm has no organs of attachment; it is retained in the intestines, constantly moving towards the incoming food masses.

8) For normal development of larvae from eggs, certain conditions are necessary, including the presence of oxygen.

9) There are bristles on the body of an earthworm.

10) Worms do not have special respiratory organs; oxygen enters through moist skin.

11) Worms loosen the soil (make passages, burrows, pass it through themselves), so many structures settle.

12) 1 – adult worm, 2 – eggs, 3 – larva with cilia, 4 – larva in the intermediate host (snail), 5 – tailed larva, 6 – cyst.

13) Digestive, excretory, nervous, reproductive systems.

14) The nervous system, which provides communication with the external environment, irritability.

15) Sexual dimorphism is the external difference between a female and a male. The female roundworm is larger than the male.

16) Circulatory system.

17) Regeneration - restoration of lost parts of the body. Regeneration can be attributed to the methods of earthworm reproduction, since the number of individuals increases.

Through things and products contaminated with soil containing roundworm eggs;

Into the intestines;
Larva;
To the lungs;
In the digestive tract;
In the intestines;
In the intestines

19) Pinworm.

21) 1 - medical leech (Leeches), 2 - sandworm (Polychaetes), 3 - earthworm (Polichaetes).

22) Leech.

4. Reflection. Final words from the teacher.

Did you like this form of lesson organization?

Which questions did you find most interesting and informative?

Your wishes and suggestions.

5. Summing up. Jury speech.

All flatworms are three-layer animals (Fig. 79). They have a skin-muscular sac that forms the cover and muscles of the body. The excretory and digestive systems appear. The nervous system consists of two nerve ganglia and nerve trunks. Free-living worms have eyes and tactile lobes. All flatworms are hermaphrodites and lay eggs in a cocoon. Flatworms are divided into ciliated, tapeworms and flukes.

Rice. 79. Flatworms: 1 - liver fluke; 2 - pork tapeworm; 3 - echinococcus; round: 4 - roundworm, 5 - pinworm; ringed: 6 - leech, 7 - earthworm

Representative eyelash worms is free-living white planaria. This animal is 2 cm long, milky white in color, lives in ponds, slow-flowing rivers, and quiet creeks. Its body is covered with cilia, the main movement of which ensures the movement of the planaria along the bottom of the reservoir. Planaria is a predator, feeding on protozoa, coelenterates, daphnia and other small animals. The planaria's throat is capable of turning outward and, due to the suction cup, tightly attaching itself to the victim.

All eyelash worms have the ability to regenerate. Under unfavorable conditions, they can disintegrate into pieces, each of which is subsequently restored into a whole organism.

The length of echinococcus is only 1-1.5 cm. Humans can become infected with it from dogs and other animals. Finna echinococcus is capable of multiplying, forming daughter blisters. Sometimes it grows to the size of a walnut, and in some cases it is as big as a child’s head. This bubble can destroy tissue and can only be removed through surgery.

Annelids. These are more highly organized animals than those discussed earlier. The body of annelids is segmented. The nervous system of the nodal type and the excretory system are well developed, and a closed circulatory system appears. There are tactile and light-sensitive cells.

Best known earthworm. This worm lives in the soil, its body is segmented, on the underside there are bristles that are directly involved in movement. If you put an earthworm on paper, you can hear the rustling sound produced by the bristles as the worm moves. It refers to class of oligochaetes.

Worms do not have special respiratory organs. They breathe through their skin. Often after rain, earthworms crawl to the surface of the earth: rainwater floods the worm burrows, displacing oxygen from the soil, which makes breathing difficult.

Earthworms are bisexual animals, but they undergo cross-fertilization. When mating, two individuals come closer, overlap their anterior ends and exchange male reproductive products. Eggs are injected into a special belt - a coupling formed from mucus, on the 13th segment, which, moving with the coupling, are fertilized with sperm on the 9th segment. The clutch containing the fertilized eggs slides off the front and forms an egg cocoon. Eggs in a cocoon develop in the soil.

Earthworms are capable of regeneration. When a worm is cut in half, the missing part can be restored.

Earthworms feed on fallen leaves and grass, passing a large amount of soil through themselves, thereby loosening it, aerating it and enriching it with humus. They play a very important role in soil formation.

Lives in sewage polluted water bodies tubifex, serving as food for fish and purifying water from organic contaminants.

In our fresh water bodies there are false horse leech black and gray-green medicinal leech. U medical leech in the depths of the oral cavity there are three ridges with pointed chitinous teeth. They are located at the vertices of the triangle, with teeth facing each other. By sucking, the leech cuts through the skin with them, secreting hirudin, preventing blood clotting. Hirudin stops the development of blood clots, is useful for hypertension, sclerosis, strokes, and resolves subcutaneous hemorrhages.

Previously, medicinal leeches were widely used, but nowadays they have become very rare.

The large false horse leech attacks earthworms, mollusks, and tadpoles. It does not cause any harm to humans, although it sometimes attaches itself to the body of a person bathing in a pond using its rear suction cup.

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§ 58. Animal Kingdom. Multicellular organisms: sponges and coelenterates§ 60. Arthropods