Main characteristic features Ring Worms are:

Secondary, or nominal, body cavity;

The appearance of blood and respiratory systems;

Sectional system in the form of metanephridium.

a brief description of

The main classes of type are non-timeline, multi-minded, leeches.

A.G. Lebedev "Preparing for the Biology Exam"

Main Aromorphoses:

1. The emergence of the secondary cavity of the body-organizer.

2. Metor structure body.

3. The appearance of a closed circulatory system.

4. Extraction system of methonephridial type.

5. A higher organized nervous system and senses.

6. The emergence of respiratory organs.

7. The emergence of organs of movement.

The overall characteristics of the ringed worms.

An extensive group of animals, including about 12k species.

Inhabit mainly in the seas, as well as in fresh waters and on land.

They are characterized by the following features of the organization:

1. Metomium (correct repetition of similar to each other organs along the axis of the body of the animal). Externally, this is expressed in the fact that the entire body of the worm is divided with harshs on separate segments (rings). Therefore, the ring worms are also called the ringers. Along with the outer, there is an internal segmentation, which is expressed in the repeatability of many internal organs.

As a result, each segment to some extent is an independent unit of a holistic system.

Metomirion can be homonal (all segments are the same) and heteronal (if the segments differ from each other). For ringworms, it is characterized mainly chomona segmentation.

Metomirion arose with the need to increase mobility by increasing the muscles and muscle mass in length. However, it comes to a new problem management and increase the amount of organs to ensure full-fledged life.

Thus, the biological meaning of metomium in general is:

a) solving the problem of body management;

b) all the processes of vital activity are strengthened, as the same organs are repeated;

c) the stock of biological strength increases;

d) due to the presence of metomery, ringed worms are capable of regeneration.

From an evolutionary point of view, segmentation opens the way to specialization and defraentials of cells, which leads to a decrease in energy costs. And the emergence of heteronal segmentation. The occurrence of heteromonian segmentation is observed in some ringed worms, for example, in nonreide.

2. For the first time, the rings are noted the process of cefollization, that is, the formation of the head unit.

3. The skin-muscular bag is well developed.

Due to what, the collected worms make complex wave-like and re-elated movements. The lateral growth of body-parpletium body, which are the organs of movement, play a major role. Parapodya is another one of the ways to increase the mobility of ring worms. Best of all paropodies from multi-singing rings.

Unlessnickens and leeches of parplets were subjected to one degree or another, reduction.

4. Killed worms Have a secondary body cavity. Unlike the primary cavity of the body of the schisoycel, the whole has been lined with a special kind epithelium. In essence, it is an internal organ and has its own walls.

Overall, as well as the whole body of ringed worms, segmented.

5. The digestive system is well differentiated to the departments.

Some species have salivary glands. The front and rear part of the intestine of ectodermal origin, medium endodermal origin.

6. The main allocation bodies are metanephria. This is an open excretory system associated with the whole and ensuring not only the function of the selection, but also the regulation of the water regime.

Methanefridia are located in segments. In this case, the metanephridium funnel is located in one segment, and the excretory channel opens in the adjacent segment.

7. In most ringed worms, a closed circulatory system. This means that blood is flowing only by vessels and there is a network of capillaries between the arteries and veins.

8. Breathing is carried out through the skin, but some representatives have new respiratory gills.

In the gills turns the dorsal parapody.

9. The nervous system consists of paired spinal coggles and the abdominal nervous chain.

Paired spines along the brain are divided into front, medium and rear gangli. This is the difference from the previous groups of worms.

10. The senses are developed to the best degree than flat and round worms.

There are eyes capable of many rings to accommodation. Touch bodies, equilibrium organs (stamotocists), chemical feelings, and some more hearing organs arranged by type of locators.

Ring Worms in most separately, but is often observed hermaphroditism. Development often flows with metamorphosis. A typical larva of marine rings is called Trichor (carrier cilia).

Thus, the progressive features of the organization are traced in the ring worms: the presence of the organizer, the metaalog of the structure, the appearance of the blood system, methanephridium, a higher-organized nervous system and sense organs. Along with these features, there are signs rapping them with lower worms (primitive signs: the larvae of three phophylas has a primary body cavity, protonfridia, an orthogonal nervous system, and on early stages Development, blind intestine).

These features are found in adult rings from primitive groups.

Type includes 3 classes:class Polychate or Multi-Point Worms, olehechta class or Unavythinkic worms, leech class.

Class Polyhetete (Multi-Point Worms)

The central class of ring worms, which is distinguished by the greatest amount of species.

Some ringed worms are freely floating in water, for example, non-rigid, others are buried in the sand, for example, Peskodel. There are seating polychates living in lime tubes, such as Serpulides and crawling in the bottom of Afrodites.

External structure Polyhete.

The body consists of a head unit, segmented torso and anal leopard (Peregidius).

The head unit is formed by a head blade, a surgery and the mouth segment of the -peristomium. On the head, many polycetes have eyes and feeling appendages. For example, at Nereda there are 2 pairs of eyes, tentacles, twin-chip plates and olfactory pits. On the peristomium there is a mouth from below, and several pairs of mustache on the sides. The body consists of segments, the number of which can reach up to 800.

Free-breed stray polychite is best expressed by chomona segmentation. Heteroman segmentation is inherent in seating and partly to the milling forms.

On the torso segments there are par of refinery, with which polychaetes float, crawl or break into the ground. Each paroption consists of a basal part and two blades: spinal (notopodia) and abdominal (insection). At the base of the parmeta on the spinal side there is a dorsal, and on the abdominal side of the abdominal mustache. Some species of the dorsal mustache parpleti turns into filament gills. Paropodies armed with bristles with bristles consisting of an organic matter close to chitina.

One of the bristles of each blade is most developed and is called acycula. This is a supporting bristle. The muscles are attached to its base, leading the entire bundle. In some species, leading or attached lifestyle, parplets are reduced. Anal blade does not bear any appendages.

Skin-muscular bag.

The body polychite is covered with a single epithelium, which highlights thin cuticle to the surface. Epithelium can be wilderness. It is rich in unicellular glands that allocate mucus and substances, of which many seating polychas build their pipes. Under the epithelium, the annular and longitudinal muscles occur. Longitudinal muscles form 4 strongly developed tapes: 2 on the dorsal side and 2 on the abdominal.

In addition, there are oblique muscles, passing obliquely from the dorsal part of the skin-muscular bag to the abdominal. Secondary body body cavity. In fact, it is a bag filled with a strip fluid, which is separated from all tissues and organs by a nuclear epithelium of mesodermal origin.

Thus, the longitudinal muscles, intestines and internal organs are covered with single-layer epithelium.

Another feature of the organizer in a polychaete is to his metaidral structure.

This means that each body segment polychate has essentially its cavity, fully separated from the cavities of the neighboring segments with special partitions consisting of two-layer epithelium.

In addition, the organic cavity in each segment is fully divided into the right and left half of the longitudinal, also a two-layer partition. Inside this partition passes the intestine, and over and under the intestines, also inside this partition, are spinal and abdominal blood vessels.

That is, in each inner segment of polychites there are 2 nominal bags. The epithelial walls of these bags are closely adjacent on one side to the muscles of the skin-muscular bag, and on the other to the intestines and each other, covering the intestine from both sides and blood vessels. This part of the walls of the nuclei bags is called spinal and abdominal mesenter or splatter.

Overall performs several functions:

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See more:

1. Continue fill in the table.

2. Explain the approval.

For the first time, ring worms have a secondary body cavity and cellular structure. In inner structure A circulatory system appears. The excretory system is represented by more developed metanephrides. Most of the rings are free-lived, some have a semblance of feet - parapody. All bilateral symmetry. There are organs of feelings.

We will write about the protective function of partitions.

Each segment of ringworms is separated by a partition and has a full set of nerve nodes, nephonds, ring vessels and sex glands. If the integrity of one segment is broken, it affects the vital activity of the worm affects a small extent.

4. List the features of the structure of the rings.

Some types of rings have parapody and bristles for movement.

Those species that do not have parapodies have bristles or their body is covered with mucus for better sliding. The muscular system of all rings is represented by annular and longitudinal muscles.

5. We will finish the scheme.
a) digestive system of rings
b) the nervous system of rings
c) organs of the senses of rings
6.

We will write about the division of the body of the ring.

Regeneration can occur, and the worm will restore lost parts. That is, there will be a useless reproduction.

7. We write an answer to the formation of the belt.

Maybe. In some multi-pectic worms living in the seas and related ring worms, reproduction occurs in water, exterior fertilization.

But most of the rings reproduction occurs with the help of a belt.

8. Explain the relationship.

There is a direct relationship between the number of discharge eggs and care for the offspring. Some polycetes are laying down a bit of eggs, and the female guards them. This means that Killed Worms are more progressive than previous types of worms.

We list the power methods Polyhete.

Among the multi-minded worms there are predators that feed on small marine animals. There are omnivorous, filtering water and fed by plants.

10. We will finish the proposals.

Polish development occurs with alternating life forms.

Their larvae are not like adults. Each life form performs various functions: reproduction, resettlement, self-preservation. Some polychites have concern for offspring.

11. We will finish the scheme.
Value Polyhete in Nature

Filter water.
2. They feed fish.
3. Feed on remnants of dead animals.

12. We will write differences in the nutrition of different worms.

Unavythinkic worms feed on organic substances from the plant residues, and predators, and omnivorous, and roasting are found among multish items.

We will write common devices from the simplest and oligochet.

To transfer adverse conditions, many simplest form a cistol, and the oligochettes are a protective capsule, and fall into the range. These formations are similar to the functions performed.

14. Denote in the figure the structure of the rainworm. Make a conclusion.

Conclusion: The primary body cavity is supported. It contains a liquid that gives the body of the worm of elasticity.

We list the features of leeches.
1) constant number of body segments (33)
2) Availability of suckers for attaching to the sacrifice or substrate.
3) the absence of bristles on the body.
4) All leeches live in aquatic environment.

16. We call foods of leeches.

17. Determine the type and class of worms.

Explain the feature of the leech.

Vehives have a nervous system developed better.

19. Explain the approval.

The statement is not true. The leeches are very sensitive to the purity of water and dying in contamination. The oligochetes are still enduring water pollution and can live long in such water bodies.

Wire an answer about guitars.

The girudine is necessary for the obstacle to blood coagulation in the victim's wound and in the stomach itself of the leech itself. If it is not produced, the leech will not be able to eat, as the blood will come.

21. We call the role of leeches in medicine.

The leeches are used in medicine to reduce blood pressure in hypertension and the threat of hemorrhage, stroke.

We indicate the characteristics of the college worms classes.
Classes like ringed worms.

A - 1, 2, 8, 10, 16
B - 4, 6, 11, 12, 17
B - 3, 5, 7, 9, 14, 15

We write the answers to crossword number 1.

Answers:
1. Capsule
2. Subtle
3. Polyhetes
4. cavity
5. Chain
6. Oligochettes
7. Chain
8.

Breath
Keyword: rings

Type of ringed worms

Aromorphosis type:

1) the presence of movement organs;

2) the appearance of respiratory and closed circulating system;

3) Secondary body cavity.

The type of ring worms covers about 8,000 species of higher worms, which have a much more complex organization than previous types.

Main features like:

The body of worms are composed of a head blades (narrowness), segmented torso and rear anal blades (Pihydia). On the head blades there are organs of feelings.

There is a well-developed skin-muscular bag.

3. The secondary cavity of the body or the whole (the space between the body wall and the internal organs with its own epithelial lining, which separates the strip fluid from all surrounding tissues and organs, appears at the ringed worms. It is divided into cameras in accordance with external segmentation.

4. The river hole lies on the abdominal side of the first trunking of the body.

The digestive system is composed of oral cavity, pharynx, middle intestine and realer, opening out anal hole at the end of anal blade.

5. Most has a well-developed closed circulatory system.

6. Options are performed by metanephridia.

Metaphridia is called open excretory organs, unlike closed protonfritis.

MetaPridia begins with a more or less expanded funnel - nephrosty, seated with cilia and opening in the cavity of the segment. From nephrosta, the nephond canal begins, which takes place in the next segment. Here the channel forms a complex tangle and opens with an excretory hole out.

The nervous system consists of paired over-and-sodium ganglia, associated with the ocular nervous ring and the abdominal nervous chain. The latter is a pair of longitudinally pinned trunks forming nerve nodes in each segment.

The most primitive collected worms of separatogues; Part of the partly appears hermaphroditism.

9. Egg crushing goes on a spiral type.

10. At the lowest type of development, development proceeds with metamorphosis, a typical larva - Throhofor.

According to the most common look, the ringed worms occurred from the lowest non-banned worms.

The type is divided into three classes - the unobtinka (the representative of the rainworm), multi-minded (Nareis, Ponkodel) and leeches.

It is believed that in the course of evolution, multi-minded gave the beginning of arthropod.

1. Flat worms:

a) two-layer animals;

b) three-layer animals.

Specify the separation organs at the bull chain:

a) protonfridia;

b) metanephrium;

3. Intermediate owner of the hepatic sequence:

a) cow;

b) Small Prudovik;

c) man.

4. The complication of round worms compared to flat is associated with the appearance:

a) three-layer body structure;

b) nervous system;

c) hermaphroditism;

d) through digestive system.

a) type round worms;

b) class of ribbon worms;

c) class of seashers?

How many layers of muscles have round worms?

a) one; b) two; at three o'clok.

7. How many segments has a rainworm body?

a) 20-30; 6) 250; c) up to 180; d) 50.

8. Among the ringed worms, real parapodies have only:

a) oligochet; b) Polyhete; c) leeches.

For Polyhete, it is characteristic (-th; -o):

a) separatability;

b) hermaphroditism;

c) binding.

10. What body cavity at Nered:

a) intestinal; b) primary;

c) secondary; d) filled with parenchym

Literature

R.G. Zayats, I.V. Rachkovskaya et al. Biology for applicants. Minsk, "Unipress", 2009, p. 129-177.

2. L.N. Pescentskaya. Biology.

Minsk, "Avermev", 2007, p. 195-202.

3. N.D. Lisov, N.A. Lemes and other biology. Minsk, "AVERSEV", 2009, p.169-188.

4. E.I. Shepelevich, V.M. Glushko, T.V. Maksimova. Biology for schoolchildren and applicants. Minsk, "Universalpress", 2007, p. 404-413.

general characteristics

The type of ring worms is an extensive group (12 thousand species). It includes secondary-haired animals whose body consists of repeating segments, or rings. Blood system for ringed worms closed. Compared to round worms, ringed have a more perfect nervous system and sense organs. We need to tell more about the main signs of this group.

The secondary cavity of the body, or the whole (from Greek. Koiloma - "deepening", "cavity"), develops at the embryo from the Mesoderm layer. This space between the body wall and the internal organs. Unlike the primary body cavity, the secondary from the inside is lined with its own inner epithelium. Whole filled with liquid creating constancy interior environment organism. Due to the pressure of the liquid, the secondary cavity supports a certain body shape and serves as a support when moving. In other words, it serves as a hydraulic cooler. The organic fluid participates in the metabolism: tolerates nutrients, accumulates and displays outward harmful substancesAnd also displays sex products.

In the collected worms, the segmented body: it is divided into the segments, or rings (hence the name - ring worms). There may be several or hundreds of such segments. The body cavity inside is divided into segments by transverse partitions. Each segment is an independent compartment: it has its own outdoor grows, nodes of the nervous system, separation organs and sex glands.

For the type of ring worms include multi-minded worms and unauthorized worms.

Habitat, building and vital activity of multi-minded worms

About 7,000 species are known for multi-art worms. Most of them live in the seas, few live in fresh waters, in the litter of tropical forests. In the seas, multiscount worms live on the bottom, where they crawl among the stones, corals, overgrown with sea vegetation, buried in il. Among them there are seating forms that build a protective tube and never leave it (Fig. 62). There are planktonic species. There are a multi-sever mixture in the coastal strip, but sometimes at a depth of 8000 m. In some places, up to 90 thousand multi-singing worms live on 1 m2 of the seabed. They eaten crustaceans, fish, iglojrine, intestinal stripes, birds. Therefore, some multi-singing worms specifically divorced in the Caspian Sea as food for fish.

Fig. 62. Diverse Multi-Pointed Ring Worms: 1 - Sitting Form of Marine Worm: 2 - Nersis; 3 - marine mouse; 4 - Peskodov

The body of multi-minded worms stretched, slightly flattened in the spinal abdominal direction, or cylindrical, from 2 mm to 3 m. Like all ringed worms, the body of multi-dimensional consists of segments, the number of which among different types ranges from 5 to 800. In addition to a plurality of torso segments There is a head department and anal blade.

On the head of these worms there are pair of papies, a pair of tentacles and a mustache. These are the organs of tanging and chemical feeling (Fig. 63, a).

Fig. 63. Nersis: A - Head Department; B - parapodnya (transverse section); In - larva; 1 - tentacle; 2 - pepatic; 3 - mustache; 4 - Eyes: 5 - Schedules

Skin-muscular growths are noticeable on the sides of each body segment - organs of motion that is called parapodies (from Greek. Couple - "near" and podion - "leg") (Fig. 63, b). Parappodias have peculiar reinforcement - brushless beams, contributing to the rigidity of the movement organs. The worm swalls the parapodies in front of the back, clinging behind the irregularity of the substrate, and thus crawling forward.

In sedentary forms of worms, partial reduction (abbreviation) of parapody occurs: often they are saved only in the front of the body.

The body of multi-plate worms is covered with a single-layer epithelium. In sedentary forms of worms, the selection of epithelium can harden, forming a dense protective case around the body. The skin-muscular bag consists of thin cuticle, skin epithelium and muscles (Fig. 64, a). Under the skin epithelium there are two layers of muscles: transverse, or annular, and longitudinal. Under the muscle layer there is a single-layer inner epithelium, which from the inside sweeps the secondary cavity of the body and forms partitions between segments.

Fig. 64. Transverse (a) and longitudinal (b) cuts through the body of unreisted (the arrows shows the flow of blood according to the vessels): 1 - paraperation; 2 - longitudinal muscles; 3 - Ring Muscles: 4 - intestine; 5 - abdominal nervous chain; 6 - spinal blood vessel; 7 - abdominal blood vessel; 8 - oral hole; 9 - throat; 10 - Brain

Digestive system It begins his mouth, which is on the abdominal side of the head blade. In the next mouth, a muscular throat, many predatory worms have chitinic teeth who serve to grasp mining. Behind the throat follows the esophagus and stomach. The intestine consists of three departments: front, middle and rendering (Fig. 64, b). The middle intestine has a view of a straight tube. It takes digestion and suction of nutrients. Fecal masses are formed in the reaches. Anal hole is located on anal blade. Stray multi-minded worms are mostly predators, and seats feed in water with small organic particles and plankton.

Respiratory system. Multi-singing worms of gas exchange (oxygen absorption and carbon dioxide absorption) is carried out either by the entire surface of the body, or parapody sites, inward blood vessels. In some sedental forms, the respiratory function performs the whisk of a tental on the head blades.

The circulatory system in the ringed worms is closed: in any portion of the body of the Worm Blood flows only by vessels. There are two main vessels - spinal and abdominal. One vessel passes over the intestine, the other is under it (see Fig. 64). They are connected with each other with numerous semir vessels. There are no hearts, and the blood movement is provided by the cuts of the spinal vessel walls in which blood is coming Behind in the back, in the abdominal - front back.

Selective system Posted by pair tubes located in each body segment. Each tube begins with a wide funnel facing the body cavity. The edges of the funnel are seated with familiar cilia. The opposite end of the tube opens out on the side of the body. With the help of a system of excretory tubes, life products that accumulate in a nominal fluid are outlined.

Nervous system It consists of paired durable, or cerebral, nodes (ganglia) connected by heavy tapes in the octopic ring, steam abdominal nervous chain and nerves departing from them.

Sense organs The most developed in the stray multi-art worms. Many of them have eyes. Touch and chemical feelings are located on antennas, ugnes and parapody. There are equilibrium organs. Touching and other stimuli act on sensitive skin cells. The excitation arising in them is transmitted by nerves to the nerve nodes, from them on other nerves - to the muscles, causing them to reduce them.

Reproduction. Most of the multi-brain worms of diocepacles. Sex glands are available in almost every segment. Mature sex cells (in females - eggs, in males - spermatozoa) fall first in general, and then through the channels of the excretory system - in water. Outdoor fertilization. From the egg develops a larva (see Fig. 63, B), which floats with cilia. Then she settles on the bottom and turns into an adult worm. Some species multiply and useless. One type of worm shares across, and each half restores the missing part. In other subsidiaries do not diverge, and as a result, a chain is formed, which includes up to 30 individuals, but then it disintegrates.

Type of ringed worms (Annelida)

We will get acquainted with a very interesting group of animals, the structure and behavior of which did not leave even Charles Darwin. He devoted a lot of time to studying the ringed worms and wrote several scientific works about them.

Among the worms, the ringed are considered the most progressive group. This conclusion is done primarily on the basis of the structure of animals.

Type of ringed worms Includes secondary-haired animals whose body consists of repeating segments, or rings. Ring Crafts have closed circulatory system .

Secondary body cavity , or whole (from Greek. koiloma - "Deeperation", "cavity"), develops in the embryo from the Mesoderm layer. This space between the body wall and the internal organs. In contrast to the primary body cavity, the secondary is wiping with its own inner epithelium. The secondary body cavity is filled with a liquid that creates the constancy of the body's interior. This liquid participates in the metabolism and provides the activity of digestive, blood, excretory and other organ systems.

In the ringed worms, the segmented structure of the body, that is, their the body is divided by For each other, the following sections -segments , or rings (Hence the name - Killed Worms). There may be several of these segments of individual species, or hundreds. The body cavity is divided into segments by transverse partitions.

Each segment is to some extent independent compartment, because it has nodes of the nervous system, the selection organs (paired nephria) and sex glands. Each segment may have lateral growths with primitive limbs - parapodies armed with bristles.

The secondary cavity of the body, or the whole, is filled with a liquid, the pressure of which supports the shape of the body of the worm and serves as a support when moving, that is, the whole ishydravelope . The organic fluid carries the nutrients, accumulates and displays the substance harmful to the body, and displays sex products.

Musculature consists of several layers of longitudinal and annular muscles. Breathing is carried out by leather. The nervous system consists of a "brain" formed by pair ganglia, and the abdominal nervous chain.

A closed circulatory system consists of abdominal and spinal vessels connected in each segment with small ring vessels. Several of the most thick vessels in the front of the body have thick muscle walls and play the role of "hearts". In each segment, blood vessels are branched, forming a thick capillary network.

Some ringed worms of hermaphrodites, others differ males and females. Development direct or with metamorphosis. Occasionally digestive reproduction (budding).

Their sizes range from a few millimeters to 3 m. Total ring worms are 7,000 species.

Interactive Trial Lesson (Go away all the lesson pages and do all tasks)

Ring Worms - Progressive a group of worms. Their body consists of sets of ring segments. By body body is divided into internal ne roots, respectively, the number segments. Ring worms have different systems of organs. They have blood system appears and parry organs of movement - a presence of future extremities .

The most famous representatives of Anneld for each person are leeches (Hirudinea subclass) and earthworms (Lumbricin cross), which are also called rain. But there are more than 20 thousand species of these animals.

Systematics

To date, the type of Annelid experts are from 16 to 22 thousand modern species of animals. There is no uniform approved classification of rings. The Soviet Zoologist V.N. Beklemishev, a classification was proposed, which is based on the separation of all representatives of the ringed worms into two essays: the worn, which includes polychas and echiurides, and pious, including oligochet and leech.

Below is a classification from the site of the World Research Institute of Marine Species.

Table of biological systematics of ringed worms

Annual Annelida Incertae Sedis is allocated, which includes controversial views. In addition to the worldwide register of marine species, such a controversial group, as Mizostomid (Myzostomida), has entered the detachment, which other classifications refer to multi-minded worms or even allocate in a separate class.

• Multi-piece class(Polycetes). Class representatives have connected side appendages (parapody) carrying chitin bristles; The name of the group is determined by the presence of a large number of bristles with the calculation for each segment. Head with appendages or without them. In most cases - separately; Gamets are discarded directly into water, where fertilization and development occurs; Free floating and called triphorms. Sometimes multiplied by rebeling or fragmentation. The class has more than 6,000 species that are divided into free-lived and seated shapes.
• Class Piyask (Clitellata). Representatives of the body on the body have a slight amount or do not have bristles in general. Parapody is absent. Characterized by the presence of a unique reproductive body - a belt that is formed from a cocoon residue and performs a protective function for fertilized eggs. The class has about 10,000 representatives.
  • Subclass of maloshetinkovoy(Oligochettes). It is inhabited primarily in fresh water. Have bristles arising directly from the walls of the body, due to small number which (as a rule, on 4 on each segment) the subclass was called the name of unauthorized. Pods on the body, as a rule, do not have. Hermaphrodites. The development is direct, the larvae is absent. There are about 3250 species.
  • Subclass of leeches. Inhabited mainly freshwater reservoirs, but there are also terrestrial and marine forms. There are a small sucker at the front end of the body and a large suction cup at the rear end. Fixed number of body segments 33. Body cavity is filled connective tissue. Hermaphrodites. Fertilized eggs are postponed in a cocoon. The development is direct, the larvae is absent. There are about 300 species of representatives.

Echiurida class (Echiura). This is a small group consisting of only about 170 famous species, all of which are exclusively marine inhabitants. Echiurid's collected worms took recently after DNA examinations, and before it was a separate type. The reason is that their body is different - it does not have segmentation, like the ringed. Some sources of echiurides are considered not as a separate class, but as a subclass of polychets.

Spread

Anneldides, depending on the species, live on land, in fresh and salted water.

Multi-point worms, as a rule, are inhabited in sea water (with the exception of certain species that can be in freshwater reservoirs). They are food for fish, crayfish, as well as birds and mammals.

Unavythinkic worms, to the subclass of which belongs to the rainworm, live in soil, filled with humid or fresh reservoirs.

Echihurides are distributed only in marine water bodies.

Morphology

The main characteristic of the representatives of the Annelida type is considered to be the separation of the body into a number of cylindrical segments, or a metairol, the total number of which, depending on the type of worms, fluctuates widely. Each metaker consists of a section of the body wall and body cavity compartment with its internal organs. The number of external rings of worms corresponds to the number of internal segments. Anneld body consists of a head area (aptomium); a torso consisting of a metaode; and segmented rear blade called pyigidium. In some primitive representatives of this type, metamera are identical, or very similar to each other, each of which contains the same structures; In more advanced forms there is a tendency to consolidate some segments and restriction of certain organs to certain segments.

Anneld's outer shell (skin-muscular bag) includes an epidermis, surrounded by cuticle, as well as well developed, segmentally located muscles - ring and longitudinal. Most Annelid possess external short bristles consisting of chitin. In addition, on each metamer, some representatives of this type of animal may have primitive limbs, called parapody, on the surface of which bristles are placed and sometimes zhar. The spatial movement of worms is carried out either by reducing the muscles, or the movements of parapody.

Anneldel body length ranges from 0.2 mm to 5 m.

Digestive system Ring worms consists of an non-integnated intestine, which passes through the middle of the body from the oral cavity located on the bottom side of the head, to rear aislelocated on anal blade. The intestine is separated from the body wall by the cavity called the whole. Segmented pricks compartments are usually separated from each other with thin sheets of tissue, called partitions, which perforate the intestine and blood vessels. With the exception of leeches, the whole of representatives of the collected worms is filled with liquid and functions as a skeleton, providing muscle movement, as well as transport, sexual, excretory function of the body. In case of damage to the integrity of the body of the worm, it loses the ability to move properly, since the functioning of the muscles of the body depends on maintaining the volume of nominal fluid in the body cavity. In primitive collides, each compartment is connected to outside With the help of channels for the release of genital cells and paired excretal organs (nephonds). In more complex species and excretory and reproductive functions Sometimes serviced by one type of channels (when the channels may be absent in certain segments).

Circulatory system. In the ring worms for the first time in the process of evolution, a circulatory system appeared. Blood usually contains hemoglobin, red respiratory pigment; However, some Annelid contains chlorocruquerine - a green respiratory pigment that gives blood to the corresponding color.

The circulatory system is usually closed, i.e. enclosed in well-developed blood vessels; In some species, the polychite and leech appears a circulatory system of an open type (blood and strip liquid are mixed directly in the bodies of the body cavity). The main vessels - the abdominal and dorsal - will connect with the network of ring vessels. Blood is distributed in each segment of the body of the side vessels. Some of them contain contractile elements and serve as a heart, i.e. Play the role of pumping bodies leading blood.

Respiratory system. Some water annelides have thin-walled, filament gills, through which gas exchange between blood and the environment. Nevertheless, most of the representatives of this type of invertebrates have no special organs for gas exchange, and breathing occurs directly through the body surface.

Nervous systemAs a rule, consists of a primitive brain, or a ganglium located in the head area connected by the rings of the nerves with the abdominal nervous chain. In all body metrors, a separate nerve node is located.

The sense of killed senses usually include eyes, taste receptors, tactile tentacles and stavocists - bodies responsible for equilibrium.

Reproduction Annelde occurs in sexual or useless way. Miscellaneous reproduction is possible by fragmentation, renovation or division. Among the worms that are multiplied by gender, they meet hermaphrodites, but most species of separation. The fertilized eggs of marine ringed eggs are usually developing in freely floating larvae. Eggs of earth forms are in cockcocks and larvae, as miniature versions of adults.

The ability to restore the lost parts of the body is highly developed in many multi-all-timing representatives of Anneld.

Environmental importance

Charles Darwin in the book The Formation of Vegetable Mould Through The Action of Worms (1881) presented the first scientific analysis of the effects of rainworms on soil fertility. Some of the worms are digging holes in the soil, while others live exclusively on the surface, as a rule, in wet fallen leaves. In the first case, the animal can break the soil so that oxygen and water can penetrate into it. Both superficial and digging worms help improve the soil with several ways:

• by mixing organic and mineral substances;
• due to the acceleration of the decomposition of organic substances, which in turn makes them more accessible to other organisms;
• by concentrating minerals and transform them into more easily digestible for plants form.

The rain worms are also an important prey for birds of raspberry to storks, and for mammals, ranging from earthquakes to badgers, and in some cases.

Ground annelides in some cases may be invasive (listed in a certain area). In the glacial regions of North America, for example, as scientists believe, almost all local rainworms were killed by glaciers and worms, which are currently located in these areas (for example, Amynthas Agrestis) were imported from other areas, primarily from Europe , and recently, from Asia. Northern deciduous forests were subjected to a particularly negative impact of invasive worms through the loss of sheet litter, a decrease in soil fertility, changes in chemical composition Soil and loss of ecological diversity.

Marine Annelides can make more than one third of the bottom species of animals around coral reefs and in tidal zones. Ringing types of ringed worms increase the penetration of water and oxygen into the seeds sediment, which contributes to the growth of populations of aerobic bacteria and small animals.

Interaction with man

Fishermen believe that worms are more efficient babes for fish than baits from artificial flies. At the same time, worms can be stored within a few days in a tin can with wet moss.

Scientists study water ring worms in order to monitor oxygen levels, salinity and environmental pollution in fresh and sea water.

The jaw polish is very strong. These advantages attracted the attention of engineers. Studies have shown that the jaws of this kind of worms consist of unusual proteins that are firmly associated with zinc.

On the island of Samoa fishing and eating one of the representatives of the ringed worms - the worm Palolo is a national holiday, and the worm itself is considered local residents of the delicacy. In Korea and Japan, we use the worms of Urechis Unicinctus from the Echiuride class.

Cases of use of leeches for medical purposes were known in China about 30 AD, India about 200 AD, Ancient Rome about 50 AD, and then throughout Europe. In the medical practice of the 19th century, the use of leeches was so common that their reserves in some parts of the world were exhausted, and some regions introduced restrictions or prohibitions on their exports (at the same time, medical leeches were considered as an extinct form). Most recently, leeches were used in microsurgery when transplantation of organs and their parts, skin sections. In addition, scientists argue that saliva of medical leeches has an anti-inflammatory effect, and some anticoagulants contained in it prevent the growth of malignant tumors.

For a person, about 17 types of leeches are dangerous.

The leeches can be attached to the skin cover of the person outside, or penetrate internal organs (for example, respiratory or gastrointestinal organs). In this regard, there are two types this disease - internal and outdoor validation. With an outdoor hyrudine, leeches are most often attached to human skin in the field of armpits, neck, shoulders, caviar.

Number of species: about 75 thousand.

Habitat: In saline and fresh waters, are found in the soil. Water crawl along the bottom, buried in il. Some of them lead a sedentary lifestyle - build a protective tube and never leave it. There are plankton species.

Structure: Bilateral symmetric worms having a secondary body cavity and divided into segments (rings) body. In the body, they allocate the head (head blade), torso and tail (anal blade) departments. The secondary cavity (whole), in contrast to the primary cavity, is lined with its own inner epithelium, which separates the nominal fluid from the muscles and internal organs. The liquid acts on the role of the hydraulic. The ring worms have a skin-muscular bag consisting of one layer of skin epithelium and two layers of muscles: ring and longitudinal. On the body there may be muscular grown - parapody, which are vehicle organs, as well as bristles.

Circulatory system For the first time appeared during the evolution in the ringed worms. It is closed type: blood is moving only by vessels, not falling into the body cavity. There are two main vessels: the dorsal (carries blood from behind in the back) and the abdominal (carries blood to front of back). In each segment they are connected by annular vessels. Blood moves due to the ripple of the spinal vessel or "hearts" - ring vessels 7-19 body segments.

The respiratory system is absent. Ring Worms - aerobes. Gas exchange occurs through the entire surface of the body. Some multi-point skin gills appeared - parapodius grows.

For the first time during the evolution, multicellular separational organs - metanefridia. They consist of a funnel with cilia and excretory channel located in the next segment. The funnel is facing the body cavity, the tubules open on the surface of the body separatingly sometime, through which decomposition products are removed from the body.

Nervous system It is formed by the incapacity of the nerve ring, which is particularly developed by the paired durable (brain) gangliya, and the abdominal nervous chain, consisting of pairwise epipped abdominal nerve nodes in each segment. From the "brain" ganglia and the nervous chain moves the nerves to organs and the skin.

Feeling organs: Eyes - organs of vision, pepatoes, tentacles (antennas) and Ugings - the bodies of touch and chemical feelings are located on the head blades in multi-art. In unauthorized in connection with the underground lifestyle, the senses are poorly developed, but in the skin there are photosensitive cells, tanging and equilibrium organs.

Reproduction and development

We multiply in gender and nonsense by fragmentation (separation) of the body, due to the high degree of regeneration. Multi-playing worms also occur to boring.
Multi-point - separation, and non-timing and leeches - hermaphrodites. Outdoor fertilization, Hermaphrodites - Cross, i.e. worms exchange seed liquid. Freshwater and soil worms Development direct, i.e. Young individuals come out of the egg. In marine forms, the development is indirect: from the egg it turns out the larva - Trichofor.

Representatives

The type of ring worms are divided into three classes: multi-art, unobtrey, leeches.

Unavythinkic worms (oligochettes), mostly dwell in the soil, but there are freshwater forms. A typical representative living in the soil is a rainworm. It has an elongated, cylindrical body. Small forms - about 0.5 mm, the most large representative reaches almost 3 m (gigantic rainworm from Australia). On each segment of 8 bristles, four pairs of the sides of the segments are located. Censing them for the unevenness of the soil, the worm with the help of the muscles of the skin-muscular bag moves forward. As a result of nutrition with rotting plants and humus, digestive system It has a number of features. Its front department is divided into a muscular pharynx, esophagus, goiter and muscular stomach.

The rainworm breathes through the entire surface of his body due to the presence of a thick subcutaneous network of capillary blood vessels.

Rain worms - hermaphrodites. Fertilization cross. Cryships are applied to each other with abdominal sides and exchange seed fluid, which falls into seed. After that, the worms are diverged. In the front third of the body there is a subtle, which forms a mucous membrane, eggs are deposited into it. When promoting the coupling through segments containing seed recipients, eggs are fertilized with sperms belonging to another individual. The coupling is reset through the front end of the body, compacted and turns into an egg cocoon, where young worms develop. For raindling worms, high ability to regenerate is characteristic.

Longitudinal cut of the body of the rainworm: 1 - mouth; 2 - throat; 3 - esophagus; 4 - goiter; 5 - stomach; 6 - intestine; 7 - Occollectric ring; 8 - abdominal nervous chain; 9 - "Hearts"; 10 - spinal blood vessel; 11 - abdominal blood vessel.

The value of the oligochet in the soil formation. Even Ch. Darwin noted their useful influence on soil fertility. Slipping the remains of plants into minks, they enrich it by humus. Putting in the soil moves, they contribute to the penetration of air and water to the roots of plants, loosen the soil.

Multi-point. Representatives of this class are also called polychate. They live mainly in the seas. The clad body polychet consists of three departments: a head blade, segmented torso and the rear anal blade. Head blades are armed with appendages - tentacles and carries small eyes. The next segment is a mouth with a throat, which can be turned out and often has chitinous jaws. On segments of the body there are two-way parapodies armed with bristles and often having gill growing.

Among them are active predators who can float rather quickly, wavely flexing the body (Neret), many of them lead a way of life, spending long minks in the sand or in Ile.

Fertilization is commonly external, the embryo turns into a characteristic larvae - a threefore, which is actively floating with cilia.

Class Leeches Combines about 400 species. Vehives have an elongated body and fightered in the spinal abdominal direction. In the front end there is one mouth suction cup in the back - another suction cup. They do not have parapody and bristles, they float, waving a wavely flexing body, or "walk" on the ground or leaves. The body of leeches is covered with cuticle. Leeches - hermaphrodites, the development is direct. They are used in medicine, because Due to the isolation of the protein of the girutin, the development of blood clots, blocking blood vessels, is preventing blood vessels.

Origin: The ringed occurred from primitive, similar to flat cilia worms. Multi-stitched unawares occurred, and from them - leeches.

New concepts and terms:, Polycetes, oligochettes, whole, segments, parapody, metanefridia, nephrost, closed circulatory system, skin gills, trichofora, weight.

Questions for consolidation:

· Why did the collee worms got such a name?

· Why are ringworms call as secondary-free?

· What features of the structure of ringed worms indicate their higher organization compared to flat and round? What bodies and system systems for the first time appear in ringed worms?

· What is characteristic of the structure of each body segment?

· What is the meaning of the ringed worms in the nature and life of a person?

· What are the features of the structure of ringed worms due to their lifestyle and habitat?