What color is an earthworm? Earthworm color, body shape and size

Animals, suborder earthworms. The body of an earthworm consists of ring-shaped segments, the number of segments can reach up to 320. When moving, earthworms rely on short bristles, which 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 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 shape of the worm’s body is explained by its way of 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 abdominal side. Approximately where the front part of the body ends, the worm has a thickening called the girdle. It contains special glands that secrete a sticky liquid. During reproduction, an egg cocoon is formed from it, inside which the worm eggs 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 the worms themselves crawl along the path. It is precisely because they appear on the surface of the earth after rain that they are called rain. These worms also crawl to the surface of the earth at night. Usually earthworm 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 it breathes. An earthworm breathes over the entire surface of its body, which is covered with mucous, moist skin. There is too little air dissolved in the water, and therefore the earthworm suffocates there. It dies even faster in dry soil: its skin dries out and breathing stops. In warm and humid weather, earthworms stay closer to the surface of the earth. During prolonged drought, as well as cold period they crawl deep into the ground.

Moving

An earthworm moves by crawling. At the same time, it first retracts the front end of the body and clings to uneven soil with bristles located on the ventral side, and then, contracting the muscles, pulls up the rear end of the body. Moving underground, the worm makes passages in the soil. At the same time, he pushes the earth apart with the pointed end of his body and squeezes between its particles.

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

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

The muscles of an earthworm are located in two layers. Under the skin lies a layer of circular muscles, and below them is a thicker layer of longitudinal muscles. Muscles are made up of long contractile fibers. When the longitudinal muscles contract, the body of the worm becomes shorter and thicker. When the circular muscles contract, on the contrary, the body becomes thinner and longer. By contracting alternately, both layers of muscles cause the movement of the worm. Muscle contraction occurs under the influence nervous system, branching into muscle tissue. The movement of the worm is greatly facilitated by the fact that there are small bristles on its body on the ventral side. They can be felt by running a finger moistened 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. They also hold him back when he is pulled out of the ground. With the help of bristles, the worm descends and rises along its earthen passages.

Nutrition

Earthworms feed mainly on half-rotted plant remains. They drag leaves, stems, etc. into their burrows, usually at night. 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 blood vessels, contracting, drive blood throughout the worm’s body.

The blood of an earthworm is red; it is very important for the worm, as for other animals. With the help of blood, communication between the animal’s organs is established and metabolism occurs. Moving through the body, it spreads from the digestive organs nutrients, as well as oxygen supplied through the skin. At the same time, blood is carried from the tissues into the skin carbon dioxide. Various unnecessary and harmful substances, formed in all parts of the body, enter the excretory organs along with the blood.

Irritation

The earthworm has no special sense organs. It perceives external irritations with the help of the nervous system. The earthworm has the most developed sense of touch. Sensitive tactile nerve cells are located throughout the surface of his body. The sensitivity of the earthworm to various kinds of external irritation is quite high. The slightest vibrations in the soil cause it to quickly hide, crawling into a hole or into deeper layers of soil.

The importance of sensitive skin cells is not limited to touch. It is known that earthworms, without special organs of vision, still perceive light stimulation. If you suddenly shine a flashlight on a worm at night, it quickly hides.

The animal's response to stimulation, carried out using the nervous system, is called a reflex. There are different types of reflexes. The contraction of the worm's body when touched and its movement when suddenly illuminated by a lantern has a protective value. This is a protective reflex. Grasping food is a digestive reflex.

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

Reproduction

Unlike hydra, earthworms reproduce exclusively sexually. It does not reproduce asexually. Every earthworm has male organs- testes, in which the living creatures develop, and female genital organs - ovaries, in which eggs are formed. The worm lays its eggs in a slimy cocoon. It is formed from a substance secreted by the worm's girdle. In the form of a muff, the cocoon slides off the worm and is pulled together at the ends. In this form, the cocoon remains in the earthen burrow until the young worms emerge from it. The cocoon protects the eggs from dampness and other unfavorable influences. 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 body parts are restored.

Annelids have the highest organization compared to other types of worms; For the first time, they have a secondary body cavity, a circulatory system, and a more highly organized nervous system. U annelids inside the primary cavity, another, secondary cavity was formed with its own elastic walls made of mesoderm cells. It can be compared to airbags, one pair in each segment of the body. They “swell”, fill the space between the organs and support them. Now each segment received its own support from the bags of the secondary cavity filled with liquid, and the primary cavity lost this function.

They live in soil, fresh and sea water.

External structure

The earthworm has an almost round body in cross section, up to 30 cm long; have 100-180 segments, or segments. In the anterior third of the body there is a thickening - the girdle (its cells function during the period of sexual reproduction and egg laying). On the sides of each segment there are two pairs of short elastic setae, which help the animal when moving in the soil. The body is reddish-brown in color, lighter on the flat ventral side and darker on the convex dorsal side.

Internal structure

Characteristic feature internal structure is that earthworms have developed real tissues. The outside of the body is covered with a layer of ectoderm, the cells of which form the integumentary tissue. The skin epithelium is rich in mucous glandular cells.

Muscles

Under the cells of the skin epithelium there is a well-developed muscle, consisting of a layer of circular muscles and a more powerful layer of longitudinal muscles located under it. Powerful longitudinal and circular muscles change the shape of each segment separately.

The earthworm alternately compresses and lengthens them, then expands and shortens them. Wave-like contractions of the body make it possible not only to crawl along the burrow, but also to push the soil apart, expanding the movement.

Digestive system

The digestive system begins at the front end of the body with the mouth opening, from which food enters sequentially into the pharynx and esophagus (in earthworms, three pairs of calcareous glands flow into it, the lime coming from them into the esophagus serves to neutralize the acids of rotting leaves on which the animals feed). Then the food passes into the enlarged crop and a small muscular stomach (the muscles in its walls help grind the food).

The midgut stretches from the stomach almost to the posterior end of the body, in which, under the action of enzymes, food is digested and absorbed. Undigested remains enter the short hindgut and are thrown out through the anus. Earthworms feed on half-rotted plant remains, which they swallow along with the soil. When passing through the intestines, the soil mixes well with organic substances. Earthworm excrement contains five times more nitrogen, seven times more phosphorus and eleven times more potassium than regular soil.

Circulatory system

The circulatory system is closed and consists of blood vessels. The dorsal vessel stretches along the entire body above the intestines, and below it is the abdominal vessel.

In each segment they are united by a ring vessel. In the anterior segments, some annular vessels are thickened, their walls contract and pulsate rhythmically, thanks to which blood is driven from the dorsal vessel to the abdominal one.

The red color of blood is due to the presence of hemoglobin in the plasma. It plays the same role as in humans - nutrients dissolved in the blood are distributed throughout the body.

Breath

Most annelids, including earthworms, are characterized by cutaneous respiration; almost all gas exchange is provided by the surface of the body, therefore the worms are very sensitive to moist soil and are not found in dry sandy soils, where their skin quickly dries out, and after rains, when in the soil a lot of water, crawling to the surface.

Nervous system

In the anterior segment of the worm there is a peripharyngeal ring - the largest cluster nerve cells. The abdominal nerve chain with nodes of nerve cells in each segment begins with it.

This nodular type nervous system was formed by the fusion of nerve cords on the right and left sides of the body. It ensures the independence of the joints and the coordinated functioning of all organs.

Excretory organs

The excretory organs look like thin, loop-shaped, curved tubes, which open at one end into the body cavity and at the other outside. New, simpler funnel-shaped excretory organs - metanephridia - remove harmful substances into external environment as they accumulate.

Reproduction and development

Reproduction occurs only sexually. Earthworms are hermaphrodites. Reproductive system they are located in several segments of the front part. The testes lie in front of the ovaries. When mating, the sperm of each of the two worms is transferred to the seminal receptacles (special cavities) of the other. Cross fertilization of worms.

During copulation (mating) and egg laying, girdle cells on the 32-37 segment secrete mucus, which serves to form an egg cocoon, and a protein liquid for nutrition developing embryo. The secretions of the girdle form a kind of mucous coupling (1).

The worm crawls out of it with its back end first, laying eggs in the mucus. The edges of the coupling stick together and a cocoon is formed, which remains in the earthen hole (2). Embryonic development of eggs occurs in a cocoon, from which young worms emerge (3).

Sense organs

The sense organs are very poorly developed. The earthworm does not have real organs of vision; their role is played by individual light-sensitive cells located in skin. The receptors for touch, taste, and smell are also located there. Earthworms are capable of regeneration (easily restore the back part).

Germ layers

The germ layers are the basis of all organs. Annelids have ectoderm (outer layer of cells), endoderm (inner layer of cells) and mesoderm ( intermediate layer cells) appear at the beginning of development as three germ layers. They give rise to all major organ systems, including the secondary cavity and circulatory system.

These same organ systems are subsequently preserved in all higher animals, and they are formed from the same three germ layers. This is how higher animals repeat in their development evolutionary development ancestors

The ocean floor is as diverse as earth's surface. Its topography also contains mountains, huge depressions, plains and cracks. Forty years ago, hydrothermal springs were also discovered there, later called “black smokers.” See the photo and description of this wonder below.

Opening of "Alvin"

It is unknown how many more years the world would not have known about “black smokers” if not for the expedition of Robert Ballard. In 1977, with his team of two, he set out to study depths of the sea on the Alvin apparatus. This most famous manned submersible is capable of descending to a depth of 4.5 kilometers.

Endogenous earthworms are the ones we gardeners encounter most often. They live in the soil in horizontal burrows. The blackish worm makes vertical portions in the soil, pulling organic matter from the surface into its burrows. These worms benefit our gardens by creating an intricate web of hollow burrows in the soil that allow oxygen and water to enter and carbon dioxide to be released. They also allow for better penetration into plant roots, resulting in more resilient trees and nutrient availability for growing plants.

This time he didn't have to swim that far. Hydrological springs were discovered already at a depth of 2 kilometers, clinging to the bottom near the Galapagos Islands. They look like huge growths from which fountains of black water gush out. At a depth of several hundred meters from the bottom, due to the clouds released by the “smokers”, almost nothing is visible. But below is a complete picture of this oceanic miracle.

And these earthworm poop - more commonly known as castings - also help create a fine, loose soil structure. Anectic earthworms make vertical burrows in the soil. They emerge from leaves and other organic matter from the surface and draw them into their burrows. As they feed on all this organic matter, they excrete it as castings around the entrance to their burrows.

If you've ever wondered where those little piles of soil come from that look like they were exorcised from a tiny tube of toothpaste and carved out with graceful art, the answer is sterile earthworms. Fat, blue-gray body; yellow tip on tail; yellow ring on the neck. Very big; red-brown body; flat tail. Big; dark gray-brown body. So how can you tell how many earthworms you have? Many people will worm at the wrong time of year, says Trish.

More than 500 hydrothermal vents are now known. They are located in the area of ​​ridges at the junctions of earth platforms. Over forty years, they were visited by hundreds of scientific expeditions. Tourists also have the opportunity to see them with their own eyes, although it costs about several tens of thousands of dollars.

How do they work?

"Black smokers" are hot springs similar to above-ground geysers. Under the influence of Archimedes' force, they throw water saturated with minerals and heated to 400 degrees into the ocean. Pressure of hundreds of atmospheres prevents water from boiling. In fact, it is in an intermediate state between gas and liquid; in physics it is called supercritical.

"You didn't find much in the summer - it's too hot and too dry." This is when some worms are dormant; they burrow deep down, and you might find them when you dig in deep soil: "They'll all be curled up in a knot, waiting for the rains to come again," she says. Other types of worms do not have this ability and instead leave their eggs ready to hatch when conditions are more favorable.

The average garden has several different ecosystems in one small space. Lawns, decorative beds, compost piles, worm farms and vegetable gardens provide habitat for different species of earthworms. Signs that you may not have a healthy earthworm population may include animal manure or compost left on the soil; slow lawn growth; deformed or stunted plant roots; water flowing over the surface of the soil; and certain layers of organic matter are obvious when you dig a hole.

Black smokers are located primarily at mid-ocean ridges. In these areas, active tectonic processes occur, under the influence of which a new crust is formed. When lithospheric plates move apart, the magma underneath them comes out, growing in ridges to the bottom.

Generally, "earthworm" is the term used to refer to any worm whose body is segmented, burrows into the soil, and is classified in the class Oligochaeta. Without much observation, these two types of worms can be easily confused. The earthworm's body is usually segmented and reddish-brown in color. Various types earthworms range in size from a quarter of an inch to about 6 inches. Stripes appear in some species of red wigglers. Red wiggler worms, otherwise just red worms, typically thrive in warm conditions, so composting beds benefit the most from them.

The formation of “smokers” is also associated with these processes. Cold sea water seeps through numerous cracks in the middle ridges. Below it is heated by volcanic heat and mixed with magma. Over time, it makes its way to the top and is thrown out through a hole in the bark.

Their water is black because it contains oxides of copper, zinc, iron, manganese and nickel. The hole from which the mixture comes out is gradually overgrown with walls of cooled metals. Branched outgrowths of bizarre shapes can reach 20, 30, and even 60 meters. After some time, they fall to the bottom, and the source continues to build up other flasks.

Moreover, they adapt to temperature fluctuations, surviving in environments that range in temperature from freezing to about 95 degrees Fahrenheit. Another fact about red wigglers is that they are large breeders that live on organic waste and the microorganisms found in them. In contrast, earthworms thrive in open gardens; you're most likely to find them in backyards and flower beds. Considering that their survival requires wet soil, earthworms typically burrow into the ground as soon as surface conditions become unbearably dry and cold.

"White Smokers"

“Black smokers” at the bottom of the oceans are not the only ones of their kind. In addition to them, there are also white hydrothermal springs. They operate on a similar principle, only the temperatures in them are much lower. They are removed from the edges of the plate and the direct heat source, located on older rocks than basalts - peridotites.

What sections can the body of an annelid worm be divided into? (head, body, tail)

Why were they given such a name (their body consists of segments)

Humidity below 70% represents an unfavorable condition. Since the substrate is dry, it is difficult for the animal to slide across the medium, as well as when swallowing food. Humidity levels below 55% or above 95% are fatal to earthworms. They stop reproducing and growing, and spermatophores do not hatch until conditions are favorable. In nature, earthworms move across prairies through tunnels they dig and seek out moist areas.

The earthworm is photophobic because ultraviolet rays animals are killed within seconds. It has sensors in the epidermis that help them detect the origin of light and move away from it. On the other hand, direct sunlight increases the temperature of the environment, reaching lethal temperatures if the animal is unable to escape.

Dimensions? (0.5mm-3m)

Symmetry (two-way)

How many layers of cells does their body consist of (three)

What muscles do they have (circular and longitudinal)

Parapodia (something like legs)

What appears for the first time (circulatory system)

Equipment and materials: Petri dish, wet filter paper, magnifying glass.

Work progress

3. The body of annelids consists of identical segments.

4. Annelids have no body cavity.

5. The nervous system of annelids is represented by the peripharyngeal nerve ring and the dorsal nerve cord.

Explanation.

1) 2 - annelids have a closed circulatory system;

2) 4 - annelids have a body cavity;

3) 5 - the nerve chain is located on the ventral side of the body.

Homework: Paragraph 10, paraphrase

Earthworms are one of the most ancient inhabitants of 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 the fundamental factor for the formation of the fertile layer.

General characteristics and living conditions

Earthworm body shape, color, size - this unique characteristics invertebrate. Let's take a closer look.

The body of the worm is made up of many ring-shaped segments. In some individuals their number reaches 320. The worms move with the help of short bristles located on these segments. Externally, the body of individuals resembles a long tube.

For their normal functioning, the humidity level must be at 75%. Worms die if the soil dries out and the humidity drops to 35% or lower. This is due to the fact that they breathe through their skin. Consequently, they simply cannot live in dry soil and water.

The most optimal temperature for their comfortable life is from 18 to 24 degrees above zero. If it starts to get colder, the worms begin to go deeper, where it is warmer and more humid. If 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.

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

The benefits of worms

It is thanks to worms that the soil throughout the planet is in constant movement. The lower layers rise to the top and are saturated with carbon dioxide and humic acids. These invertebrates provide potassium and phosphorus.

Worms are better than any human hands and technicians prepare the soil for plant growth. Thanks to these creatures, even large stones and objects sink deep into the ground over time. And small pebbles are gradually ground in the stomach of the worms and turn into sand. However, excessive use chemicals person in agriculture inevitably leads to a reduction in their population. Today, there are already 11 species of earthworms in the Red Book of Russia.

Color

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

If the worm lacks skin pigments, it will be pink or red throughout its life. In the presence of this component, the color of the earthworm can be brown, blue, yellow or brown.

For example, the Allophora chlorotica worm is yellowish or greenish in color. A Lumbricus rubellus - earthworms are brown-red or purple in color with a pearlescent tint.

Body length

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

Types of worms

Invertebrate animals 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		They constantly form new tunnels, but feed in the humus layer
	They constantly make deep passages, but only the upper end of the body can come out for food consumption and mating.

Littering and burrowing individuals are characteristic of waterlogged soils. In other words, they live near ponds, 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.

Worm nutrition and digestive organs

Regardless of the type and color of the earthworm, they are all omnivores. By ingesting huge amounts of soil, they consume half-rotten leaves. From this mixture they receive useful substances. They do not eat only leaves with an unpleasant odor, but they like fresh leaves.

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

After digesting the soil, the worm rises out and throws it out. Excreta, soaked in intestinal secretions, is viscous and hardens when dried in air. There is no randomness in their actions; waste is first dumped on one side, then on the other. As a result, a characteristic turret-like entrance to the burrow is formed.

Worms not only feed on leaves, plant stems, and scraps of wool, they use them to plug the entrances to burrows.

In all earthworms, regardless of body shape and color, the mouth is located at the front end of the body. The swallowing process occurs due to the muscular pharynx. After this, food - earth with leaves - enters the intestines. If some part of the food has not been digested, it is thrown away along with the processed food. The release 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 by lightly touching them. After this, each worm secretes mucus from a “belt” located on the front of the body, into which 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. Their tactile sense works best. 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 soil. These elements are also responsible for the perception of light. After all, such individuals do not have eyes. But if you shine a flashlight on them at night, they will quickly hide.

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

Even Darwin noticed that such creatures are distinguished by their smell. If the worm does not like the aroma of food, then he will refuse such a meal.

Animal enemies

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

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

Vermiculture

IN lately became current topic organic vegetable growing. The question may arise as to what worms have to do with it. It's very simple. Vermiculture is based on the cultivation of earthworms. In this case, it does not matter at all what color the earthworm is, the most important thing is the production of vermicompost. Recent trends suggest that vermiculture will soon completely replace harmful chemical fertilizers from agriculture.

Since ancient times, humanity has turned special attention at such unsightly creatures as earthworms. And scientific minds, in the person of Charles Darwin, decades later, for many years studied their structure and significance in agriculture. And not without reason. Indeed, with the onset of spring warmth, earthworms begin painstaking work and work, without knowing it, for the benefit of people.

Features and habitat

Earthworm , he is also a ringed one - a well-known resident on any personal plot. And it would seem absolutely unnoticeable, to no one necessary creation.

However, any person who is at least somehow connected with the land will be very happy to have such inhabitants of his garden. IN Russian Federation There are no more than a hundred species of earthworm. But all over the world there are one and a half thousand varieties of them.

It belongs to the family of annelids, the oligochaete class. Its entire long body consists of many rings. There may be seventy of them, or maybe all three hundred. Since it grows more than twenty-five centimeters in length.

But there are also the smallest ones, two or three centimeters. The Australian earthworms reach two and a half meters in size. Its color is literally gray-brown - crimson.

Also, on each ring, or it is also called a segment, there are bristles. Our ordinary garden worms, as a rule, grow eight bristles. They are classified as oligochaetes.

However, there are also tropical, polychaete species of worms in which the villi grow in dozens. The bristles help the worms crawl, absolutely over all soil tubercles or burrow into holes.

You can find them by holding the worm in your hands and running your finger from back to front. But since to an inexperienced person, it’s hard to determine where his butt is, you can just lightly run your hand along the body and back. You can feel it right away. In one direction the worm will be absolutely smooth, and in the opposite direction it will be rough.

Anyone who has ever picked up a worm knows that it is covered with not very pleasant mucus, which is vital for it. Firstly, mucus helps the invertebrate move freely in the ground. Secondly, since the worm does not have lungs, it breathes through the skin. And thanks to the moisture found on the mucus, the body is saturated with oxygen.

Self earthworm body consists of two groups of muscle tissue. They are longitudinal and transverse. The transverse muscles are under protective top layer worm skin.

With their help, the worm becomes as long as possible. And the stronger muscles are longitudinal. They cut and make the body smaller. This is how the animal moves, sometimes lengthening, sometimes shortening.

The earthworm belongs to the secondary cavity animals. Consequently, he has a complete closed circulatory system. Because their life activity is active.

The muscles contract many times more often than in protocavitary worms. To do this, they need blood to provide the worm with all the nutrients and oxygen.

IN the structure of an earthworm there are a pair of blood vessels, one of them is called dorsal, the second abdominal. Ring vessels connect them to each other. Blood flows through them from back to front, and vice versa.

Each ring, or segment as it is also called, has a pair of tubes. The funnels at their ends open and feces are discharged through the bottom. earthworm. This is the working principle excretory system.

As for the nervous system, it is nodal. Its components are the ventral nerve cord and the peripharyngeal nerve ring. These endings consist of fibers, and they, in turn, respond to the urges of the contracted muscles of the worm. Thanks to them, the worm can eat, move purposefully, reproduce, and develop.

In the building earthworm organs Those responsible for smell, touch, vision, and sensation are absent. But there are certain cells, they are located along the entire body of the invertebrate. With their help, the worm navigates in the dark and impassable ground.

Character and lifestyle

Charles Darwin also suggested the presence of intelligence in earthworms. Watching them, he noticed that when dragging a dry leaf into his home, it was turned with the narrow side. This makes it easier for a leaf to pass through a dense, earthy burrow. But on the contrary, he takes spruce needles by the base so that they do not fork.

All day, all life of rain worm scheduled by the minute. Every now and then he climbs in the ground, makes moves, swallowing it. The worm digs holes in two ways. He or, as already mentioned, swallows the earth, gradually moving forward.

In case the ground is too hard. And then leaving yours biological waste. Or, he pushes it with his refined end, into different sides, and makes his own moves. The passages are obliquely vertical.

Same rain worm, subsistence in the soil, drags into its holes, for insulation, various leaves, veins from leaves, thin pieces of paper and even scraps of wool. Its burrows are up to one meter deep. And the worms are larger in size, and all ten meters. The worm works mainly at night.

A why earthworms crawl to the surface in huge quantities. This means he can't breathe. This usually happens after heavy rains. The earth is clogged with moisture, and there is no oxygen for him at all. When the cold weather arrives, earthworm goes deep into the soil.

Earthworm nutrition

The worm's diet is quite typical. Swallowing in large quantities land along with food. Withered and slightly rotten leaves and mushrooms are suitable for them to eat. But she shouldn't have unpleasant odor, otherwise the worm will not eat it.

It turns out that earthworms even build entire storage rooms for themselves and store food there for winter. They eat it only in case of critical need. For example, in winter time, when the ground is completely frozen, and there can be no talk of any terrestrial food.

Having sucked in the food along with a lump of earth, through the pharynx, with muscular movements, now expanding his body, now narrowing it, he pushes it to the back of the esophagus into the goiter. Afterwards, it penetrates the stomach. From the stomach it is sent to be poisoned in the intestines, thanks to enzymes, and comes out as useful biomass.

Making moves, and at the same time having a snack, rain to the worm need to crawl out periodically to the surface to throw off the earth. At the same time, he adheres to the hole with his tail edge, as if holding on to it.

And after that, there are always earthen slides. The soil processed by the worm turns out sticky. Then it dries and becomes small balls, about the size of a match head.

These balls are saturated with vitamins, enzymes, and organic substances, which, as a result, kill all bacteria in the soil and prevent rotting, which is very important for plant roots. And they also act on the composition of the earth as an antiseptic, disinfecting it.

Reproduction and lifespan

Earthworms can be heterosexual or hermaphrodite. All earthworms have thickenings on the front third of their body. They contain the ovary and testis. Hermaphrodites release seed into each other. Already ripe testicles, up to ten pieces, are inseminated. And they crawl away in different directions.

When a female individual is ready to reproduce, she approaches her partner and copulates. Something like a cocoon is formed on it, consisting of several dozen thickened segments.

It is divided by a kind of belt. This cocoon receives all the nutrients necessary for the brood. After fertilization, the worm removes this burden from itself; it simply slides off the animal.

The edges of the cocoon are quickly pulled together on both sides so that the future offspring do not dry out before they are born. Then, over the course of four weeks, small worms mature and hatch.

Once born, they scatter in all directions. And from the first days of their lives they begin active work to process the land. And already at three months of age, grown-up children reach the size of adults.

Another fact about earthworms is the ability to regenerate. If someone or something splits it into two halves. Over time, each half will become a full-fledged individual. This is one of the methods of reproduction, but no longer sexually.

The role of the earthworm very important in agriculture. Firstly, they saturate the soil with oxygen, which is so necessary for everything growing on it. With their moves, they help the roots to fully develop.

Moisture is distributed evenly, and the soil is well ventilated and loosened. Thanks to constant movement earth, with the help of worms, stones are extracted from it.

Also, with their recycled adhesive residues, they glue the soil together, preventing it from eroding. Well, and of course they fertilize the soil when leaves and insect larvae are drawn into it. It all rots and serves as excellent, natural biological additives.