annelids have the following aromorphoses: 1. The body was divided into segments (metamers) with repeating sets of internal organs. 2. A secondary cavity appeared - the whole, which has its own mesodermal lining. 3. There has been further complication nervous system: concentration of nerve cells on the ventral side in each segment (abdominal nerve chain formed), a significant increase in the brain ganglia (nodes) (supraesophageal, subesophageal nerve ganglia, peripharyngeal ring). 4. A closed circulatory system arose, which ensured the rapid transport of substances throughout the body. 5. Respiratory organs appeared, which increased the respiratory surface and the intensity of gas exchange. 6. Made it harder digestive system: there was a differentiation of the middle intestine into sections, which led to a phased process of digestion. 7. Parapodia formed - limbs for movement. 8. There was a further complication of the excretory organs: a metanephridial multicellular excretory system was formed.

• Earthworm

Earthworm – Lumbricus terrestris(type Annelids, class Small-bristle worms, Lumbricidae family) lives in moist, humus-rich soil. It feeds on organic matter, passing earth with plant debris through the intestines. Ch. Darwin also noted useful influence earthworms on soil fertility. Dragging the remains of plants into the mink, they enrich it with humus. Laying passages in the soil, they contribute to the penetration of air and water to the roots of plants.

Active earthworms in warm time of the year. In winter they hibernate. Freezing kills worms instantly, so they must burrow deeper into the ground where low temperatures do not penetrate. In the spring, when the temperature reaches a suitable value and the ground is saturated with rainwater, they have a mating season. They reproduce very quickly, producing about a hundred young worms a year. In summer, the worms are not so active. Food - dying plant residues - is very scarce at this time, and the soil is devoid of moisture, which can cause the death of worms. autumn period again characterized by worm activity. At this time, the reproduction of offspring begins again, which lasts until the onset of winter.

Earthworms live relatively long lives. Some manage to live for about ten years if they do not become victims of birds and moles. Another threat to their lives is the pesticides so widely used in horticulture today.

So, the Earthworm has an elongated, cylindrical body from 10 to 30 cm long. dorsal side more rounded, it is darker, a dorsal blood vessel shines through its skin. Abdominal side somewhat flattened and lighter colored. The anterior end of the body is thicker and darker colored. The body is made up of rings segments. In an adult worm, their number reaches 200. In the area of ​​\u200b\u200b32-37 body segments there is belt rich in mucous glands. External segmentation corresponds to the division of the body cavity by partitions into separate chambers and the segment-by-segment (i.e., in each segment) arrangement of a number of internal organs. On each segment 8 bristles(they are easy to detect if you run your finger along the body of the worm in the direction from the rear end of the body to the front). The setae are arranged in four pairs on the lateral sides of the segments. Clinging to the unevenness of the soil with them, the worm moves forward with the help of the muscles of the skin-muscular sac.

Covers. Body earthworm covered skin-muscle sac. He is educated cuticle, single layer epithelium and two layers of muscles - external ring and internal longitudinal. The skin epithelium of the worm is rich mucous pieces of iron that produce slime covering the entire body of the worm and protecting it from drying out. The mucus also makes it easier to crawl in burrows by reducing friction on the soil.

Earthworm movement. When the worm crawls, waves of muscle contractions run through its body, and both the length and thickness of individual sections of its body are constantly changing. The movements produced by each part of the body consist in the fact that the segments that make it up are sometimes stretched and at the same time become thinner, then they contract and become thicker. As a result of such alternating extensions and contractions, the worm gradually moves forward: first, its head end is pulled forward, and then the posterior segments of the body are gradually pulled towards it; after that, the rear end of the body remains in place, and the head end sticks out even further forward, and thus the further advancement of the worm continues (it is convenient to observe it by letting the worm crawl along the paper spread out on the table).

• body cavity. Inside the skin-muscular sac in annelids is located secondary cavity body, or in general. This body cavity is not limited by muscles, as in roundworms, but has its own epithelial(coelomic) pavement, i.e. the inner side of the longitudinal muscles is lined with epithelium of mesodermal origin, and there is also an epithelial lining on the side of the intestine lying in the body cavity. Due to the coelomic epithelium, internal two-layer transverse partitions are formed between the segments - dissipations. The secondary cavity is divided into chambers, each segment contains a pair of coelomic sacs. The coelomic fluid is under pressure and plays a role hydroskeleton, so the worm is elastic to the touch.

Digestive system comprises front, middle and rear guts. Mouth located on the second segment on the ventral side of the body. anal hole

type Annelids Earthworm

At the posterior end of the body, it looks like a small gap. Due to the nutrition of rotting plant remains and humus, the digestive system has a number of features. Its anterior section is differentiated into a muscular throat, esophagus, goiter and muscular stomach. To increase the suction surface, a fold has formed on the upper part of the intestine typhlosol(typhlozolis). Please note: differentiated parts of the foregut - pharynx, esophagus, goiter, stomach - were absent in previous types of worms.

Breath. An earthworm breathes over the entire surface of its body due to the presence of a dense subcutaneous network of capillary blood vessels. Therefore, it is important that the integuments of the worm's body do not dry out, but excessive moisture (for example, very wet soil after rain) is just as detrimental to them.

Circulatory system closed, that is, the blood moves through the vessels without spilling into the body cavity. The movement of blood is determined by the pulsation of large vessels, mainly encircling the esophagus. These are kind of hearts. Blood supplies all organs and tissues with nutrients, transporting them from the intestines, and oxygen entering the capillaries of the skin from the external environment. By dorsal vessel blood moves from the back end of the body to the front, and along abdominal vessel- in the opposite direction. The blood of an earthworm is red. An iron-containing protein, close to vertebrate hemoglobin and transporting oxygen, is contained in a dissolved state in the blood plasma, and erythrocytes are absent.

Nervous system more complex than that of flat and roundworms. It consists of nerve parapharyngeal ring with ganglia and abdominal nervous chains. This is the so-called nervous system ladder type. supraesophageal double ganglion performs the functions of the brain and is more developed than subesophageal. The nerve chain originates from the subpharyngeal node and is a segment-by-segment pairs of nerve nodes, connected to each other by transverse and longitudinal commissures. From the ganglia, nerves depart to various organs. The sense organs of the earthworm are poorly developed: eyes and tentacles are absent, but numerous sensory cells and nerve endings are embedded in their skin.

excretory organs are presented segment by segment (i.e., in each segment) by located paired metanephridia. They look like convoluted tubules, begin in the body cavity with a funnel with cilia. A channel departs from the funnel, which penetrates the transverse partition, passes into the cavity of the next segment. The final department of metanephridium has an extension - uric bubble, which opens outward on the lateral side of the body of the worm (i.e., each segment has a pair of very small excretory openings). In addition to metanephridia, the excretion involves chloragogenic cells covering the intestinal surface with a thin brown-yellow coating. Chlorogenic cells accumulate excretion products. Filled with metabolic products, these cells die, and their contents enter the body cavity, from where they are removed by metanephridia.

Reproduction. earthworms hermaphrodites. The reproductive organs and the girdle can only be seen during the breeding season - in the spring. To male

type Annelids Earthworm

reproductive system include two pairs of testicles located in segments 10 and 11, four vas deferens, which merge in pairs and open outward doubles male sexual hole located in segment 15. The female reproductive system includes pair ovaries located in segment 13, oviducts, which open outward in segment 14 couple women's genital holes. There are two pairs in segments 9 and 10 seminal receptacles, each of which opens outwards with an independent opening.

Earthworms reproduce sexually. Cross fertilization, in a cocoon. Two worms meet, wrap their bodies tightly around each other, attach themselves to each other with their ventral sides and exchange sperm, which enters the spermatic receptacles. After that, the worms disperse. Further, the girdle forms a mucous sleeve, eggs are laid in it. When the clutch is advanced through the segments containing the seed receptacles, the eggs are fertilized by sperm belonging to another individual. The clutch is dropped through the front end of the body, compacted and turns into an egg cocoon, where young worms develop.

Regeneration. Earthworms are characterized by a high ability to regenerate, i.e. from each piece of the torn body of an earthworm, a whole worm is restored.

Questions for self-control

Name aromorphoses of the type Annelids.

Name the classification of the type Annelids.

What is the systematic position of the earthworm?

Where do earthworms live?

What body shape do earthworms have?

What is the body of an earthworm covered with?

What body cavity is characteristic of an earthworm?

What is the structure of the worm's digestive system?

What is the structure of the circulatory system of the worm?

How does an earthworm breathe?

What is the structure of the excretory system of the worm?

What is the structure of the worm's nervous system?

What is the structure of the reproductive system of an earthworm?

How does an earthworm reproduce?

What is the significance of the earthworm?

type Annelids Earthworm

Rice. Earthworm, its moves in the ground and movement.

Rice. The internal structure of the earthworm.

1, 16 - gut; 2 - partitions; 3 - epithelial lining of the secondary body cavity; 4 - dorsal (back) blood vessel; 5 - annular blood vessel; 6 - skin-muscular sac; 7 - cuticle; 8 - skin epithelium; 9 - whole; 10 - metanephridium; 11 - eggs; 12 - circular muscles; 13 - longitudinal muscles; 14 - ventral (abdominal) blood vessel; 15 - abdominal nerve chain.

type Annelids Earthworm

Rice. The structure of the anterior end of the body of an earthworm.

The prostomium is a protrusion of the upper part of the first segment that covers the mouth. The peristomium is the name of the first segment of the body.

type Annelids Earthworm

Rice. The structure of the earthworm.

A - head end; B - internal structure; B - nervous system.

1 - mouth opening; 2 - male genital opening; 3 - female genital opening; 4 - belt; 5 - pharynx; 6 - esophagus; 7 - goiter; 8 - stomach; 9 - intestines; 10 - dorsal blood vessel; 11 - annular blood vessels; 12 - abdominal blood vessel; 13 - metanephridia; 14 - ovaries; 15 - testes; 16 - seed bags; 17 - seed receptacles; 18 - peripharyngeal ganglion; 19 - peripharyngeal nerve ring; 20 - abdominal nerve chain; 21 - nerves.

type Annelids Earthworm

Rice. Longitudinal section of the body of an earthworm.

1 - mouth; 2 - throat; 3 - esophagus; 4 - goiter; 5 - stomach; 6 - gut; 7 - peripharyngeal ring; 8 - abdominal nerve chain; 9 - "hearts"; 10 - dorsal blood vessel; 11 - abdominal blood vessel.

Rice. Reproduction of the earthworm.

1 - mucous sleeve; 2 - cocoon; 3 - exit of young worms from the cocoon.

type annelids

Rice. The structure of the polychaete worm Nereid.

type annelids

Rice. Appearance of a medical leech.

Who hasn't seen earthworms? Yes, probably everything. However, many do not even realize what benefits they have brought and are bringing to us, it is very difficult to overestimate it. This voluminous article is devoted to earthworms. The reader can learn for himself about the structure, types, and lifestyle of worms underground. If you do not know anything about these animals, then after reading the article, your attitude towards them will radically change. At the end of the publication, several videos will be shown for review. The text will be accompanied by pictures and photos.

- These are rather large invertebrates, having a size of up to 3 meters in length. Green worms that live in Russia belong to the Haplotaxida order (representatives of this order live throughout the Earth, with the exception of Antarctica) and to the Lumbricidae family, which includes about 200 species. About 97 representatives of this family live in Russia. Meaning earthworms for the earth's biosphere is very difficult to overestimate. They eat dead plant tissues and animal waste products, then they digest it all and mix the resulting mass with the soil. People have learned to use this feature for their own purposes to obtain the most valuable fertilizer - biohumus or vermicompost.

These protozoa got their name because when it rains, they crawl out of their burrows and stay on the surface of the soil. This happens because rainwater fills their holes and they have nothing to breathe and, in order to save themselves, they get out.

Biohumus is a hydrophilic structure that has the ability to accumulate moisture. That is, when there is not enough water in the soil, humus releases moisture, and when it is in excess, it accumulates. The phenomenon of humus excretion by worms is explained by studying their structure. The fact is that in the intestines of worms, after the breakdown of organic compounds, molecules of humic acids are formed, and they, in turn, come into contact with various mineral compounds.

Earthworms are very great importance in the formation of fertile soil, this fact was noticed by Charles Darwin. They dig holes for themselves with a depth of 60-80 centimeters, thereby loosening the soil.

To date, worms are very widely used by people for their own purposes. First of all, to obtain vermicompost. Worms are actively used in poultry and livestock for feeding. Worms are also widely used by amateur anglers as a good bait.

The structure of earthworms

The structure of earthworms simple enough. The length of individuals that are common in Russia varies from 2 to 30 centimeters. The whole body is divided into segments, they can be from 80 to 300. The earthworm moves with the help of very small setae, which are located on each segment of the body, with the exception of the very first. Setae on one segment can be from 8 to 20.

Picture: the structure of the earthworm

In the attached picture you can visually observe the structure of the worm. You can determine the front of the worm, where the mouth is, the back, where the anus is located. You can also see segments.

They are characterized by a closed circulatory system, which is quite well developed. It contains one artery and one vein. The worm breathes thanks to very sensitive skin cells. The skin contains protective mucus, it contains a large number of antiseptic enzymes. The brain is poorly developed. It consists of only two nerve nodes. It is very characteristic of worms to show the possibility of regeneration. For example, if you cut off his tail, then after a while it will grow back.

Earthworms are hermaphrodites, each having both male and female reproductive organs. Reproduction occurs due to the mating of two individuals. The genital organ of worms is a girdle, in size it occupies several anterior segments. The genital girdle stands out well on the body of the worm, it looks like a thickening. In this organ, a cocoon matures from which, after 2-3 weeks, small worms hatch.

Types of earthworms

Earthworms that live in our country can be divided into two types, which differ in biological features. The first species includes those worms that feed on the surface of the soil (litter), and the second one includes those that live and feed in the soil layers (burrows). The first species lives constantly on the soil surface, its representatives do not descend into soil layers that are below 10-20 centimeters.

Representatives of worms that belong to the second species deploy their activities exclusively at a depth of 1 or more meters. If necessary, they stick out of the ground only the front part of the body.

The second species, in turn, can be divided into burrowing and burrowing worms. Burrowers live in deep layers of the soil, but do not have permanent burrows. And burrow worms constantly live in the same minks.

Earthworms of litter and burrowing species live exclusively in moist soils, for example, in places near water bodies. Burrowing worms can live in drier soils.

Lifestyle of worms underground

Worms are nocturnal. At this time of the day, you can observe their most active activity. At night they eat most of the food. Many crawl out to consume food, but rarely get out of their holes completely - the tails always remain underground. Worms close their holes for a day various items such as tree leaves. They can drag small particles of food into their holes.

For reference. The body of the worms is very much stretched, thanks to the numerous segments. In addition, worms have very tenacious bristles. In this regard, forcibly pulling him out of the mink is a rather difficult undertaking.

They are omnivorous. They have very characteristic food. First, they swallow a large amount of soil, and then they absorb only useful organic substances from it.

Worms are able to digest animal feed, such as meat, even in small quantities.

Eating food takes place in burrows. First, the worm outside gropes for a tidbit and drags it into its hole, where the meal takes place. In order to capture the food object, the worm clings to it very strongly, then pulls back with all its might.

Moreover, the worms make a supply of food for themselves. They fold it very neatly into their burrows. Worms can also purposely dig another hole just to store food. They clog such a mink with moist earth and open it only if necessary.

Occurs in the following order. First, the soil is swallowed, then the organic matter is digested inside the worm. After that, the worm crawls out and excretes excrement. Moreover, he puts the products of vital activity in one specific place. Thus, before entering the hole, a kind of pile of worm excrement is formed.

Worms life

Life of earthworms has a very long history. They played a huge role in soil formation. It is thanks to them that we see the land as it is today.

Worms are constantly engaged in burrowing activities, as a result of which the earth layer is always in motion. Worms have a very large appetite. In just one day, he can eat a volume of food that is comparable to him in weight, that is, 3-5 grams.

As a result of their activity, worms contribute to best growth plants. Let's not even take into account the fertilizer they produce. Worms loosen the soil and contribute to a better ingress of oxygen and water into it. The roots of plants grow much better along the holes of worms.

As a result of the constant loosening of the soil, large objects gradually sink into the depths of the earth. Small foreign particles are gradually rubbed by the stomachs of worms and turn into sand.

Unfortunately, the number of earthworms in our country is declining. Contributes to this rational use chemicals to "fertilize" the soil. To date, 11 species of earthworms have already been included in the Red Book of Russia. Why use chemicals to fertilize the soil when there is such a miracle of nature as vermicompost?!

The role of earthworms in nature very large and hardly something overestimated. A huge role in the decomposition of organic matter belongs to worms. enrich the soil the most valuable fertilizer - humus. They can serve as an indicator: if there are a lot of them in the soil, then the land is fertile.

A complete understanding of the role of earthworms came to man relatively recently. Up to this point, they mainly resorted to the use of chemical mineral fertilizers, which destroyed the soil and all life in it. Unfortunately, many modern farmers are also in this delusion. Biohumus or vermicompost is a real magic wand for the soil. It contains a very large amount of potassium, phosphorus and nitrogen - substances that are primarily necessary for plant growth.

We've gone off topic a bit. In wildlife, worms keep to places where there is a large amount of organic waste. A good example is the forest. When the foliage falls in the fall, it will need to be put somewhere. Soil bacteria and, of course, earthworms will come to the rescue here. Immediately after the leaves fall, soil bacteria will take over and decompose it to the compost stage. Then the worms will take over the work and process the compost to the stage of vermicompost and introduce this most valuable fertilizer into the soil. Basically, this is how soil formation works.

The benefits of earthworms

At times Soviet Union on the Russian open spaces actively began to use chemical mineral fertilizers, which eventually destroy entire layers of soil. Today we have just come to the moment when the soil begins to rapidly collapse. Chernozem soils no longer give such good results like before. Unscrupulous farmers who think only about their income use fertilizers that are dangerous for the soil on their plots of land, thereby destroying it. But the restoration of the soil takes a very long period of time, about 1 centimeter in 100 years.

The benefits of earthworms is to quickly restore the earth from chemical burns and other adverse effects. restore the very structure of the soil due to the introduction and distribution of vermicompost in it. Even if the land does not need to be restored, adding vermicompost to it will in any case be beneficial. It is impossible to pollute or burn with humus, unlike any other fertilizer. And this is due to the fact that vermicompost has a very similar structure to black soil. You can even say that humus is concentrated black soil.

With the help of worms, you can bring a very great benefit to your garden, garden or small household plot. To do this, you just need to learn how to breed worms yourself, and this is very simple to do. It is enough to dig a hole in the garden and put all the organic waste there. Over time, the worms will appear there themselves. There is another option - to buy worms. You can also breed worms in separate boxes. As organic waste is eaten, the resulting vermicompost must be collected and scattered around the site.

Worms significantly improve the structure of the soil, improve water and air exchange and water exchange in it. In the garden or garden, it is necessary to create all conditions for the development of worms. It would be most rational to build a special box in which in the summer you can put all the weeds and other organic waste. The next year, with a large number of worms, you can already get ready-made fertilizer from this box, which can be used in different ways (see photo below). Some advise to simply scatter it around the site, while others bury it, and the third generally prepare liquid top dressing based on it. AT common ways there are many applications.

Earthworms - Vermiculture

Enough is engaged in breeding earthworms in order to obtain biohumus big number farmers and ordinary people who have their own household plots. And this trend cannot but rejoice. Vermiculture may soon replace harmful chemical fertilizers.

Breeding worms can also be considered as a good business idea. At minimal cost, you can get the most valuable fertilizer and sell it for good money. It is especially beneficial to engage in this business, who has a livestock of poultry or farm animals and does not know where to put their waste products. Farm animal droppings are excellent food for worms that turn into vermicompost.

In this part of the article, one cannot fail to say about the type of worms that is the most productive - the Californian. California worms were bred in 1959 in the USA. These earthworms are most often used in this area due to their enormous productivity. The California worm eats as much as the usual one, but its reproduction rate is 100 times higher, and its lifespan is 4 times longer. However, they will have to provide certain conditions of detention.

Before launching worms into the substrate, it must be prepared. It needs to be turned into compost. It is most convenient to use ordinary metal barrels with a volume of 200 liters.

At home, you can breed worms in various containers. A wooden box with small holes at the bottom to drain excess water is best suited for these purposes, a substrate is laid there and worms are launched. In one summer, a box of organic waste can be turned into vermicompost. See photo:

Compost is laid here, and non-composted organic waste can be placed on top

You can use boxes of a different design, such as plastic, in which fruits and vegetables are transported:

The disadvantage of the plastic box is too big holes at the bottom through which the worm can escape from it.

earthworm video

“The appetizing fruits and vegetables that you see are not fake. These beautiful fruits are real, and most importantly - environmentally friendly. And all this is due to the fact that they were obtained with the help of an amazing fertilizer - biohumus. In this video, we will talk about earthworms of the prospector breed. The video is very helpful and educational.

This video was shown on television, this is the Galileo program. The report was prepared about earthworms.

To enlarge an image, simply click on it.

Earthworms are one of the most ancient inhabitants of the planet Earth. They live almost everywhere, with the exception of the permafrost of Antarctica. Thanks to this boneless creature, the soil becomes fertile. It is their vital activity that is a fundamental factor for the formation of a fertile layer.

General characteristics and living conditions

The body shape of an earthworm, color, size are the unique characteristics of an invertebrate. Let's consider in more detail.

The body of the worm is a set of annular segments. In some individuals, their number reaches 320. Worms move with the help of short bristles located on these segments. Outwardly, the body of individuals resembles a long tube.

For their normal life, the humidity level should be at the level of 75%. Worms die if the earth dries up and the humidity drops to 35% or less. This is due to the fact that they breathe through the skin. Therefore, they simply cannot live in dry soil and in water.

The most optimum temperature for their comfortable life - from 18 to 24 degrees above zero. If it starts to get colder, then the worms begin to sink deeper, where it is warmer and more humid. If a atmospheric temperature does not increase, then they hibernate. If this indicator rises above 42 degrees, then the worms die. The same thing happens if the temperature is too low. And worms crawl out after rain due to lack of oxygen in the soil.

An interesting fact: it was the ability to fall into a state of suspended animation that allowed the worms to survive in the Ice Age.

The benefits of worms

It is thanks to worms that the soil all over the planet is in constant motion. The lower layers rise to the top and are saturated with carbon dioxide, humic acids. Thanks to these invertebrates, potassium and phosphorus enter.

Worms, better than any human hands and technology, prepare the soil for the growth of plants. Thanks to these creatures, even large stones and objects eventually sink deep into the ground. And small pebbles are gradually ground in the stomach of worms and turn into sand. However, excessive use chemical substances man in agriculture inevitably leads to a reduction in their population. To date, the Red Book of Russia already contains 11 species of earthworms.

Color

The color of the earthworm is directly dependent on skin pigments. But this characteristic is relevant only for living individuals.

If the worm does not have skin pigments, then it has a pink or red color throughout its life. In the presence of this component, the color of the earthworm can be brown, blue, yellow or brown.

For example, the worm Allophora chlorotica has a yellowish or greenish color. A Lumbricus rubellus - earthworms - have a brown-red or purple color with a mother-of-pearl tint.

body length

The average size of all individuals is from 5 to 20 centimeters, with a thickness of 2 to 12 mm. However, in tropical forests there are invertebrates up to 3 meters long. Naturally, with such sizes of annular segments, there can be more than 3 thousand.

Types of worms

Invertebrates live in all layers of the soil, hence the species that feed on the surface of the earth are distinguished:

Surface feeders		Soil feeders
Litter	Individuals under no circumstances fall below 10 centimeters into the ground		Living in deep soil layers
Soil-litter	They live at a depth of 10 to 20 centimeters.		Constantly form new passages, but feed in the humus layer
	They constantly make deep passages, but only the upper end of the body can go outside, for food consumption and mating

Litter and burrowing individuals are characteristic of waterlogged soils. In other words, they live near water bodies, swamps and in regions with a humid subtropical climate.

The tundra is characterized by soil-litter and litter worms. In the steppes, only soil species can be found.

Worms nutrition and digestive organs

Regardless of the type and color of the earthworm, they are all omnivores. By swallowing huge amounts of earth, they absorb half-rotten leaves. From this mixture they get useful substances. They do not use only leaves with an unpleasant odor, but they love fresh ones.

Ch. Darwin wrote about the omnivorous nature of worms. He made many experiments by hanging pieces of various foods, including the remains of dead worms, over a pot of animals, and most of this food was eaten.

After digesting the soil, the worm rises out and throws it out. Excrement, saturated with intestinal secretions, is viscous, and after drying in air, it hardens. There is no randomness in their actions; first, waste is dumped from one side, then from the other. As a result, a characteristic entrance to the mink is formed, similar to a turret.

Worms not only feed on leaves, plant stems, and tufts of wool, they use them to plug burrow entrances.

In all, regardless of body shape and color, earthworms have a mouth located at the front end of the body. The process of swallowing occurs due to the muscular pharynx. After that, food - earth with leaves - enters the intestines. If some part of the food has not been digested, then it is thrown away along with the processed food. Emission occurs through the anus located at the posterior end of the body.

reproductive system

All earthworms are hermaphrodites. Before laying eggs, two different individuals exchange seminal fluid, with a light touch. After that, each worm from the "belt" located on the front of the body secretes mucus, into which the eggs enter. After some time, the lump with them practically slides off the body and turns into a cocoon. After maturation, young individuals emerge from it.

and sense organs

Absolutely all individuals, regardless of the color of the earthworm, do not have sensory organs. The tactile sense works best for them. Similar cells are located throughout the body, and even a slight vibration of the ground causes the worm to hide and sink into deeper layers of the soil. These elements are also responsible for the perception of light. After all, such individuals do not have eyes. But if you illuminate them at night with a lantern, they will quickly hide.

Researchers claim that worms have a nervous system. This is confirmed by the fact that they have elementary reflexes: when touching the body, it instantly contracts, protecting the worm from touch.

Even Darwin noticed that such creatures are distinguished by smell. If the worms do not like the aroma of food, then he will refuse such a dinner.

Animal Enemies

It doesn’t matter at all what body color an earthworm has, what kind it has and where it lives, all individuals have natural enemies. The most terrible of them is the mole. This mammal animal not only eats worms, but also stocks them for the future. The mole has a paralyzing substance in its saliva that acts specifically on invertebrates. This is how he catches the worms.

Frogs and shrews will not disdain to taste them. Many birds eat earthworms - these are thrushes, domestic chicken, starlings and woodcocks. Many arthropods do not disdain worms - these are arachnids, different types insects and centipedes.

Vermiculture

AT recent times became hot topic organic vegetable growing. The question may arise as to what the worms have to do with it. Everything is very simple. The basis of vermiculture is the cultivation of earthworms. At the same time, it does not matter at all what color the earthworm has, the most important thing is the production of biohumus. Latest trends they say that soon vermiculture will completely replace harmful chemical fertilizers from agriculture.

The body of the earthworm is divided into segments by ring constrictions. Each segment has eight small bristles, which, when the worm moves, rest against the unevenness of the soil.

The body wall is covered with a cuticle secreted by a single-layer epithelium. Below it is a layer of circular muscles, below them are longitudinal muscles. Thanks to the alternating work of these muscles, the worm moves. The movement is facilitated by secreted mucus.

Earthworm refers to annelids with a secondary body cavity - in general. Its walls are lined with epithelium. The cavity is filled with a liquid that can carry nutrients and oxygen absorbed by the entire surface of the body. Respiratory system missing. (During the rain, the worms lack oxygen and crawl out to the surface of the soil).

The mouth is located on the ventral side of the anterior segment, and the anus is located on the latter. The worm feeds on fallen leaves and rotting plant debris, swallowing them along with the ground. Nutrients in the intestines are absorbed into the blood. Undigested residues are ejected through the anus.

Circulatory system closed. The dorsal vessel carries blood from the posterior to the anterior end of the body. Several annular vessels in segments 7–11 play the role of the heart, pumping blood into the abdominal vessel. Through the abdominal vessel, blood moves to the posterior end. Thinner vessels depart from the main vessels, passing into the capillaries. Blood contains hemoglobin, which carries oxygen. A closed circulatory system allows you to significantly increase the metabolic rate.

In each segment, except for the terminal ones, there is a pair of metanephridia - tubules that bring metabolic products out of the coelom (excretory system).

The nervous system consists of the peripharyngeal nerve ring and the ventral nerve cord. The sense organs are absent. The worm is able to perceive light and touch due to tactile and light-sensitive cells scattered over the entire surface of the body.

Earthworms are hermaphrodites, but with cross fertilization. Segments 32–37 have a belt that serves to build egg cocoons. The cocoon moves to the front end, spermatozoa, obtained in advance by mating with another individual, enter it from the spermatozoa, fertilization occurs. The cocoon slips through the head end of the worm. Development is direct, young worms hatch from eggs. Earthworms are characterized by the ability to regenerate - to restore the lost fragment of the body.

The value of the earthworm in nature

• Earthworms make passages in the soil, facilitating the penetration of air and water into the soil.
• Improve soil structure by gluing soil particles into small lumps.
• Soil fertility is facilitated by the worms dragging fallen leaves and other plant residues, their digestion and decomposition with the formation of humus.
• Earthworms serve as food for many animals: moles, shrews, hedgehogs, toads, ground beetles.
• They are intermediate hosts of helminths that cause diseases in young pigs, etc.

Animals, suborder earthworms. The body of an earthworm consists of annular segments, the number of segments can reach up to 320. When moving, earthworms rely on short bristles that are located on the body segments. When studying the structure of an earthworm, it is clear that, unlike the whipworm, its body looks like a long tube. Earthworms are distributed throughout the planet, except for Antarctica.

Appearance

Adult earthworms are 15 - 30 cm in length. In the south of Ukraine, it can reach large sizes. The body of the worm is smooth, slippery, has a cylindrical shape and consists of piece rings - segments. This form of the body of the worm is explained by the way of its life, it facilitates movement in the soil. The number of segments can reach 200. The ventral side of the body is flat, the dorsal side is convex and darker than the ventral side. Approximately where the front of the body ends, the worm has a thickening called a girdle. It contains special glands that secrete a sticky liquid. During reproduction, an egg cocoon is formed from it, inside which the eggs of the worm develop.

Lifestyle

If you go out into the garden after rain, you can usually see small piles of earth thrown out by earthworms on the path. Often at the same time, the worms themselves crawl along the path. It is because they appear on the surface of the earth after rain that they are called rain. These worms crawl out to the surface of the earth also at night. The earthworm usually lives in humus-rich soil and is not common in sandy soils. He also does not live in swamps. Such features of its distribution are explained by the way of breathing. The earthworm breathes on the entire surface of the body, which is covered with mucous, moist skin. Too little air is dissolved in the water, and therefore the earthworm suffocates there. He dies even faster in dry soil: his skin dries up, and breathing stops. In warm and humid weather, earthworms stay closer to the surface of the earth. During a prolonged drought, as well as during a cold period, they crawl deep into the ground.

moving

The earthworm moves by crawling. At the same time, it first draws in the anterior end of the body and clings with the bristles located on the ventral side to the unevenness of the soil, and then, contracting the muscles, pulls up the posterior end of the body. Moving underground, the worm makes its own passages in the soil. At the same time, he pushes the earth apart with the pointed end of the body and squeezes between its particles.

Moving in dense soil, the worm swallows the earth and passes it through the intestines. The worm usually swallows the earth at a considerable depth, and throws it out through the anus at its mink. So on the surface of the earth long "laces" of earth and lumps are formed, which can be seen in the summer on garden paths.

This method of movement is possible only in the presence of well-developed muscles. Compared to the hydra, the earthworm has more complex musculature. She lies under his skin. Muscles together with the skin form a continuous musculocutaneous sac.

The muscles of the earthworm are arranged in two layers. Beneath the skin lies a layer of circular muscles, and beneath them is a thicker layer of longitudinal muscles. Muscles are made up of long contractile fibers. With the contraction of the longitudinal muscles, the body of the worm becomes shorter and thicker. When the circular muscles contract, on the contrary, the body becomes thinner and longer. Contracting alternately, both layers of muscles cause the movement of the worm. Muscle contraction occurs under the influence of the nervous system, branching out in muscle tissue. The movement of the worm is greatly facilitated by the fact that there are small bristles on its body from the ventral side. They can be felt by running a finger dipped in water along the sides and along the ventral side of the worm's body, from the rear end to the front. With the help of these bristles, the earthworm moves underground. With them, he lingers when he is pulled out of the ground. With the help of bristles, the worm descends and rises along its earthen passages.

Food

Earthworms feed mainly on half-decayed plant remains. They drag, usually at night, leaves, stems and other things into their minks. Earthworms also feed on humus-rich soil, passing it through their intestines.

Circulatory system

The earthworm has a circulatory system that the hydra does not have. This system consists of two longitudinal vessels - dorsal and abdominal - and branches that connect these vessels and carry blood. The muscular walls of the vessels, contracting, drive blood throughout the body of the worm.

The blood of an earthworm is red, it has a very importance. With the help of blood, the connection between the organs of the animal is established, metabolism occurs. Moving through the body, it carries nutrients from the digestive organs, as well as oxygen entering through the skin. At the same time, the blood carries carbon dioxide out of the tissues into the skin. Various unnecessary and harmful substances formed in all parts of the body, together with the blood, enter the excretory organs.

Irritation

The earthworm does not have special sense organs. He perceives external stimuli with the help of the nervous system. The earthworm has the most developed sense of touch. Sensitive tactile nerve cells are located all over the surface of his body. The sensitivity of the earthworm to various kinds of external irritation is quite high. The slightest vibrations of the soil make him quickly hide, crawling into a mink or into deeper layers of soil.

The value of sensitive skin cells is not limited to touch. It is known that earthworms, having no special organs of vision, still perceive light stimuli. If at night you suddenly illuminate the worm with a lantern, it quickly hides.

The response of an animal to stimulation, carried out with the help of the nervous system, is called a reflex. There are different types of reflexes. The contraction of the body of the worm from touch, its movement when suddenly illuminated by a lantern, has a protective value. This is a protective reflex. Grabbing food is a digestive reflex.

Experiments also show that earthworms smell. The sense of smell helps the worm find food. Charles Darwin also established that earthworms can smell the leaves of the plants they feed on.

reproduction

Unlike the hydra, the earthworm reproduces exclusively sexually. It does not have asexual reproduction. Each earthworm has male organs - the testes, in which the gums develop, and the female genital organs - the ovaries, in which the eggs are formed. The worm lays its eggs in a slimy cocoon. It is formed from a substance secreted by the girdle of the worm. In the form of a clutch, the cocoon slides off the worm and is pulled together at the ends. In this form, the cocoon remains in the earthen burrow until young worms emerge from it. The cocoon protects the eggs from moisture and other adverse effects. Each egg in the cocoon divides many times, as a result of which tissues and organs of the animal are gradually formed, and, finally, small worms similar to adults emerge from the cocoons.

Regeneration

Like hydras, earthworms are capable of regeneration, in which lost parts of the body are restored.