And the cylindrical shape provides the optimal ratio of volume and surface area involved in the production of oxygen. Given that they move quite a bit, we can say that such breathing through the skin is quite enough for them.
However, the worms have a circulatory system, unlike unicellular organisms and some types of insects, the hemoglobin dissolved in the rain, which spreads through the body through the contraction of large vessels during the movement of the worm. It spreads oxygen throughout the body, and helps maintain diffusion. Large vessels are one vein and one artery, just as many vessels the worm has (except for the capillaries located under the cuticle).
As such, like mammals, the earthworm, in principle, does not, there is a very thin cover - the cuticle. Such skin is moisturized with epithelial secretion, and due to its minimal thickness allows the worm to breathe. However, such skin is not protected from drying out, because the worms must live in some kind of moist environment in order to protect the skin from drying out. Oxygen is first dissolved in water, which covers the body of the worm, and only then is absorbed into the blood through the capillaries. If the skin of the worm dries, it cannot receive from the environment oxygen and dies.
Since the earthworm practically does not come to the surface, such a breathing system is extremely beneficial for it - it can take oxygen for gas exchange directly from the soil. Between the particles of the earth there is enough oxygen to provide them with a worm. During rain, worms crawl out from under the earth to the surface, this is due to the fact that water sticks together particles of the earth, and there is no air left between them. To get the necessary oxygen, worms must rise to the surface.
To test the breathing of the earthworm, you can conduct a simple experiment: the earth is poured into the jar, several worms are laid on top. After a short time, the worms burrow into the ground, but if you water the ground with water, they will rise to the surface. Similarly, all annelids breathe - with the help of the skin, the entire surface of the body.
Earthworm is a representative of the type of annelid. Its long elongated business consists of separate segments - rings, separated by ring constrictions, which is the reason for the name of the species. Thanks to this structure, it can move freely both in dense soil and on the surface of the soil.
Instruction manual
The body of the earthworm is elongated 10-16 cm long. It is rounded in cross section, but longitudinally divided by ring constrictions for 100-180 segments. On them are elastic bristles, with which the worm clings to the unevenness of the soil during movement.
In the afternoon, the worms are in the soil and pave passages in it. Soft, they are easily drilled with the front end of the body: at first it becomes thin, and the worm pushes it between the lumps of earth forward, then, thickening, the front end spreads the soil, and the worm pulls the back of the body. In dense soil, worms can eat their own passages, passing it through the digestive tract. At night they go to the surface of the soil and leave behind characteristic earthen piles.
The skin of the earthworm is wet to the touch, as it is covered to facilitate the movement of the worm in the soil. The oxygen necessary for breathing can also penetrate only through wet skin. Under it is a skin-muscle bag - annular (transverse) muscles fused with the skin, under which lies a layer of longitudinal muscles. The former makes the body of the animal long and thin, the latter - thickened or shortened. The coordinated alternate work of these muscles also ensures the movement of the worm.
Under the skin-muscle bag you can see the body cavity filled with fluid. It houses the internal organs of the animal. Unlike roundworms, in earthworms the body cavity is not continuous, but segmented, divided by transverse walls.
Earthworm belongs to the group of annelids. He has no special organsdesigned specifically for gas exchange, and gas exchange occurs by diffusion through the entire surface of the body. In essence, they don’t need specialized organs, since due to the cylindrical shape of their bodies, the ratio of surface area to volume is large, and with their relatively low activity they do not consume much oxygen.
However, annelids there is a circulatory system (unlike some simpler animals and unicellular organisms), and the hemoglobin respiratory pigment is dissolved in their blood. Contraction of large blood vessels drives the blood along with the gases dissolved in it throughout the body; this also contributes to maintaining steep diffusion gradients.
Thin skin of an earthworm (cuticle) is constantly moisturized by the secretion of glands located in the epithelium. Capillaries are located in the epithelium directly under the cuticle. The distance between the blood vessels and the surface of the body is small and this ensures rapid diffusion of oxygen into the blood. Earthworms are practically not protected from drying out and therefore try to stay only in a humid environment.
A. Locust trachea system. B. The structure of the insect trachea.The respiratory system of insects is the locust.
Insects have gas exchange carried out through a system of tubes, the so-called trachea. Such a system allows oxygen to flow from the air directly to the tissues and there is no need to transport it with blood. This is a much faster method than diffusion of dissolved oxygen through tissues; such gas exchange creates conditions for a high metabolic rate.
Respiratory - paired openings located on the second and third thoracic and on the first eight abdominal segments of the body of the insect lead into the air cavities. From these cavities branched tubules - the trachea - depart. Each trachea is lined with epithelium secreting a thin layer of chitin material. Usually, this rigid layer is further strengthened by spiral and annular thickenings, due to which the airways remain open, even if the pressure in the tracheal lumen is negative (compare with the cartilage rings in the trachea and bronchi of a person). In each segment of the body, the trachea branches into numerous smaller tubules called tracheols; tracheoles also branch, penetrating insect tissues, and in the most active tissues, for example in the flight muscles, blindly terminate inside individual cells. The degree of branching of the tracheol may vary depending on the metabolic needs of the tissues.
In tracheols, chitin lining is absent. At rest, they are filled with an aqueous liquid; at this time, oxygen diffuses along them to the tissues (and C0 2 in the opposite direction) at a speed quite sufficient to satisfy the needs of the insect. In the active state, an increase in the metabolic activity of muscles leads to the accumulation of certain metabolites, in particular lactic acid, and the osmotic pressure in the tissues increases accordingly. When this happens, the fluid from the tracheol under the action of osmotic forces is partially absorbed into the tissue, and more air, and therefore more oxygen, enters the tracheoles, and this oxygen is supplied directly to the tissues just when they need it.
Conditions created in the tissues of the insect at rest and in an active state (tracheol work).
The total air flow passing through the body of the insect is regulated by a mechanism closing spiracles. The opening of each spiracle is equipped with a system of valves controlled by very small muscles. The edges of this hole are covered with hairs that prevent foreign particles from entering the spiracles and prevent excessive loss of moisture. The size of the hole is regulated depending on the amount of CO2 in the body of the insect.
Enhanced activity leads to increased formation of CO 2. Chemoreceptors they catch it and the spiracles open. The same stimulus can also cause ventilation movements of the body, especially in large insectssuch as locusts. Dorsoventral muscles, contracting, make the body of the insect flatter, as a result of which the volume of the tracheal system decreases and air is pushed out of it (“exhale”). Air absorption (“inhalation”) occurs passively when body segments, due to their elasticity, take their original shape.
Judging by some data, thoracic and abdominal spiracles open and close alternately, and this, in combination with the ventilation movements of the body, creates a unidirectional stream of air that enters the body of the insect through the thoracic region and exits through the abdominal.
Tracheal systemOf course, it is very effective in the sense of gas exchange, however, it should be borne in mind that in most insects gas exchange is determined exclusively by diffusion of oxygen through insect tissues. Diffusion, as is known, is effective only at short distances, and this imposes severe restrictions on the sizes that insects can reach. These small distances at which diffusion is sufficiently effective do not exceed 1 cm; therefore, although insects up to 30 cm long are found, their body should not be more than 2 cm thick.
And suborder of earthworms (Haplotaxida). His body consists of ring-shaped segments, the number of which can reach 320! These animals are widespread in all corners of our planet. They are not only in Antarctica. Very often, children are interested in how earthworms move. In our article, we will analyze this issue in detail, and at the same time we will learn about their appearance, lifestyle and method of reproduction.
Earthworm Lifestyle
If in the morning or after rain to walk through the garden, the garden, then, as a rule, you can see on the ground small piles of soil thrown out by worms, and in the puddles to see them themselves. Due to the fact that these individuals crawl to the surface of the earth after rain, such a name was attached to them. (the photo above shows this invertebrate animal) also crawls to the earth's surface at night. As a rule, he prefers humus-rich soil, so it can rarely be found in sandstones. He does not like earthworms and marshy soils. These features are explained physiological features Lumbricidae. The fact is that worms breathe the entire surface of their body, covered with mucous epidermis. Too little air is dissolved in moisture-saturated earth. As a result, the earthworm is suffocating there. By the way, this explains his behavior in the rain. Dry soil is also detrimental to the representatives of Haplotaxida: their skin dries up, and breathing stops. In wet and warm weather earthworms (the photo below shows Lumbricidae in all its glory) stay closer to the surface of the earth. With a decrease in temperature, as well as with the onset of the dry period, they crawl into the deep layers of the soil.
earthworms
Adult individuals reach 30 centimeters in length, although there are individual specimens of larger sizes. The body of the earthworm is slippery, smooth, has a cylindrical shape, consists of segments - piece rings. This constitution is explained by the lifestyle of Lumbricidae: a similar structure facilitates the process of movement in the soil. The number of piece rings reaches two hundred. The surface of the body, which could conditionally be called the back, is convex, and the abdominal surface is flat and lighter. On the body of the earthworm, where its front end is completed, there is a thickening, which is called the girdle. It contains special glands that secrete a sticky liquid. When propagating from the girdle, an egg cocoon is formed, eggs develop in it.
How do earthworms move?
Representatives of Haplotaxida crawl. First, they stretch the front end of their body and cling to special bristles, which are located on the ventral side of the rings, for the unevenness of the earth's surface. After this, muscle contraction occurs, and the back is pulled forward. The movement of the worm in the ground is characterized by the fact that it makes moves in the soil. In this case, with the pointed end of the body, he pushes the earth apart, and then squeezes between its particles. It is also interesting how earthworms move in denser layers. In the process of movement, they swallow the earth and pass it through the intestines. Worms, as a rule, swallow the soil at a considerable depth, and are thrown out through the anus already at the top, near their own mink. It can often be observed in the summer on the surface of the earth in the form of lumps and elongated “laces”.
Earthworm and its biology
Worms have well-developed muscles, thanks to which a similar method of movement became possible. Their muscles are under the epidermis, in fact, they, together with the skin, form a kind of muscular skin bag. The muscles are located in two layers. The ring muscles are located directly below the epidermis, and below them is the second, thicker longitudinal layer (consists of contractile long fibers). When the longitudinal muscles are compressed, the body of the earthworm becomes thicker and shorter. When contracting the ring muscles, on the contrary, it is long and thin. Alternating contraction of both layers of muscles, carried out under the influence of branching in muscle tissue nervous system, and causes the movement of Lumbricidae.
The movement of the worms is greatly facilitated by the presence of small setae on the lower body. They can be felt if you hold a wet finger on the abdomen of the worm from the back to the front end. Thanks to these bristles, earthworms not only move in the soil, but also “grab” the ground when they are trying to pull them out. They also help to rise and fall along already done earth passages. On this we will finish to deal with the question of how earthworms move, and move on to at least interesting facts about the life of Lumbricidae.
Circulatory system
It consists of two longitudinal vessels - the abdominal and dorsal, as well as the branches connecting them. Due to muscle contraction of the walls, blood flows throughout the body. Blood from earthworms is scarlet. With its help, a connection is established between the internal organs, and a metabolism is also carried out. While circulating, the blood carries nutrients from the digestive organs, as well as oxygen from the skin. At the same time, carbon dioxide is removed from the tissues. In addition, blood removes unnecessary and harmful compounds to the organs of excretion.
Earthworm Nutrition
The basis of the nutrition of Haplotaxida representatives is half-rotten plant remains. As a rule, at night, earthworms pull leaves, stems, etc. into their burrows. In addition, they can pass humus-rich soil through their intestines.
Earthworm irritation
Special earthworms do not have. They perceive external irritations due to the nervous system. Worms have a very developed sense of touch. The nerve cells responsible for this are located over the entire surface of the skin. The sensitivity of earthworms is so great that the slightest vibrations of the soil make them hide at the highest possible speed in burrows or in deeper layers of the earth. However, the importance of sensory nerve endings is not limited only to the function of touch. Scientists have found that with the help of these cells, earthworms are able to sense rays of light. So, if you direct a beam of a flashlight to the worm at night, then it will hide at a high speed in a safe place.
The response of animals to any irritation caused by the nervous system is called a reflex. It is customary to distinguish between reflexes of various kinds. So, the contraction of the body of an earthworm from touching it, as well as its movement in sudden light, is a protective function. This is a protective reflex. Scientists have shown that earthworms can smell. Thanks to the sense of smell, they find food.
Breeding
Earthworms reproduce sexually, although in general the primary ones are hermaphrodites. Each representative of Haplotaxida has male organs, called testes (sperm develop in them), as well as female organs, called ovaries (eggs form in them). An earthworm lays its eggs in a mucous cocoon. It is formed from a substance that is released through the girdle. Further, the cocoon in the form of a sleeve slides off the body and is pulled together at the ends. He remains in the ground until the young worms come out of it. Cocoon is used to protect eggs from moisture and other adverse effects.
What are worms for?
This section will be useful for those who think that earthworms are only needed for fishing. Of course, a fisherman without them has nothing to do without them on the river, but this is not all the benefit of the representatives of Lumbricidae. The role of the earthworm in nature is so great that it is impossible to overestimate it. They contribute to the decomposition of organic matter in the soil. In addition, earthworms enrich the earth with valuable fertilizer - humus. They are also a kind of indicator: if the soil contains many worms, then it is fertile.
A full understanding of the role of Haplotaxida came to humanity relatively recently. However, even now many farmers prefer to use chemical fertilizers, despite the fact that they kill all living things. Today, chemicals have found an alternative - vermicompost and vermicompost. In fact, this is a magic wand for the earth, because they contain a large number of phosphorus, potassium, nitrogen, that is, those substances that are vital to plants for their full growth.
Conclusion
Earthworms are the most important link in soil formation. Let's look at the process. Autumn leaves fall from the trees and cover the entire surface of the earth. Immediately after that, they get down to business and decompose the leaves to the stage of compost. And then the worms pick up the baton, which process the foliage to the stage of vermicompost. Thus, valuable fertilizers enter the soil.
Annelids have the highest organization compared to other types of worms; they first appear the secondary body cavity, the circulatory system, the nervous system is more highly organized. In annelids, another, secondary cavity with its own elastic walls of mesoderm cells formed in the primary cavity. It can be compared with airbags, a pair in each segment of the body. They “swelled”, filled 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
An earthworm has an almost round cross-sectional body 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). Two pairs of short elastic bristles are developed on the sides of each segment, which help the animal when moving in the soil. The body has a reddish-brown color, lighter on the flat abdominal and darker on the convex dorsal side.
Internal structure
A characteristic feature of the internal structure is that earthworms have real tissues. Outside, 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.
Muscle
Under the skin epithelium cells there is a well-developed musculature consisting of a layer of annular and a more powerful layer of longitudinal muscles located under it. Powerful longitudinal and ring muscles change the shape of each segment separately.
The earthworm alternately compresses and lengthens them, then expands and shortens them. The wave-like contractions of the body allow not only to crawl along the mink, but also to spread the soil, expanding the course.
Digestive system
The digestive system begins at the front end of the body with the mouth opening, from which food enters the pharynx, the esophagus (in earthworms three pairs of calcareous glands flow into it, lime coming from the esophagus serves to neutralize the acids of rotting leaves that animals feed on). Then the food goes into an enlarged goiter and a small muscular stomach (the muscles in its walls contribute to grinding food).
From the stomach to the posterior end of the body, the middle intestine stretches, in which, under the action of enzymes, food is digested and absorbed. Undigested residues enter the short hind gut and are thrown out through the anus. Earthworms feed on semi-decayed plant debris, which they swallow along with the earth. 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 ordinary soil.
Circulatory system
The circulatory system is closed, consists of blood vessels. A spinal vessel stretches along the entire body over the intestine, and an abdominal one underneath.
In each segment they are united by an annular vessel. In the anterior segments, some annular vessels are thickened, their walls contract and rhythmically pulsate, due to which the blood is distilled from the dorsal vessel to the abdominal.
The red color of the 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 carried throughout the body.
Breath
Most ringworms, including earthworms, are characterized by skin respiration, almost all gas exchange is provided by the surface of the body, therefore, the worms are very sensitive to moist soil and do not occur in dry sandy soils, where their skin dries out soon, 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 periopharyngeal ring - the largest accumulation of nerve cells. The abdominal nerve chain begins with nodes of nerve cells in each segment.
Such a nervous system of a nodular type was formed during the fusion of nerve cords of the right and left sides of the body. It ensures the independence of the joints and the coordinated work of all organs.
Excretory organs
The excretory organs look like thin, loop-like curved tubes, which open at one end into the body cavity and outward at the other. New, simpler funnel-shaped organs of excretion - methanephridia, remove harmful substances into the environment as they accumulate.
Reproduction and development
Reproduction occurs only through sexual contact. Earthworms are hermaphrodites. Their reproductive system is located in several segments of the front. Testes lie in front of the ovaries. When mating, the sperm of each of the two worms are transferred to the testicles (special cavities) of the other. Cross-worm fertilization.
During the copulation (mating) and laying of eggs, the cells of the girdle on the 32-37th segment secrete mucus, which serves to form the egg cocoon, and protein fluid to nourish the developing embryo. The discharge of the girdle forms a kind of mucous sleeve (1).
The worm creeps out of it with its rear end forward, laying eggs in the mucus. The edges of the coupling stick together and a cocoon forms, which remains in the earthen mink (2). Embryonic development of eggs occurs in a cocoon, young worms emerge from it (3).
Sensory organs
The sense organs are very poorly developed. The earthworm does not have real organs of vision, their role is played by individual photosensitive cells located in the skin. The receptors of touch, taste, and smell are also placed there. Earthworms are capable of regeneration (easily restores the back).
Germ leaves
Germ layers are the basis of all organs. In annelids, ectoderm (outer layer of cells), endoderm (inner layer of cells) and mesoderm (intermediate layer of 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.
The same organ systems are preserved in the future in all higher animals, and they are formed from the same three germ layers. So the higher animals in their development repeat the evolutionary development of their ancestors.
biouroki.ru
There are no special respiratory organs: they breathe the entire surface of the body. A thin cuticle and tenderness of the skin, a rich network of skin blood vessels provide the ability to absorb oxygen from the environment. The cuticle is well wetted by water, and oxygen is first dissolved in water. This entails the need to keep the skin moist.
Earthworms (lat. Lumbricidae) - a family of worms from the class of small-bristled (Oligochaeta), such as annelids (Annelida). This family includes fairly large worms (10 to 30 cm long) with thick skin, red blood and devoid of eyes; in each ring two pairs of small hooked bristles stick out on each side.
The genera and species of this family differ in the shape of the head extension (the so-called upper lip), in the position of the girdle and in the number of rings; In Russia, several species of earthworms from the genera are found: Lumbricus, Dendrobaena, and Allolobophora.
Earthworms live in a land in which they dig long tubular passages; at night they go to the surface of the earth; they drag various organic residues into their moves - particles of leaves and other plant parts. They feed on decaying organic matter. Feces of earthworms, containing a lot of crushed earth particles, are deposited by them on the surface of the earth. In this way, earthworms contribute to an increase in the arable layer of the earth, while at the same time they loosen the soil with their burrows, and by extracting plant debris they increase its content by organic parts.
The significance of earthworms in the process of soil formation was first indicated by Darwin.
Fertilization occurs at night, on the surface of the earth, and occurs mutually; both individuals are tightly adjacent to each other, having turned opposite ends, and the seed of one individual flows into the seed receptors of the other; in this case, both individuals are interconnected by a ring formed by the allocation of special glands of the so-called girdle; at the end of the act, the ring is reset.
Earthworms are used as bait when fishing fish.
otvet.mail.ru
There are no special respiratory organs: they breathe the entire surface of the body.
1058; a thin cuticle and tenderness of the skin, a rich network of skin blood vessels provide the ability to absorb oxygen from the environment. The cuticle is well wetted by water, and oxygen is first dissolved in water.
1069; this entails the need to keep the skin moist.
09mog.ru
Features and habitat
Earthworm , he is ringed - a well-known resident in any household plot. And it would seem, an absolutely invisible, useless creature.
However, any person, at least somehow connected with the land, will be very glad to such residents of his garden. IN Russian Federation there are no more than a hundred species of earthworm. But around the world there are fifteen hundred species.
It belongs to the family of annelid worms, low bristle class. His entire long body consists of many rings. There may be seventy, or maybe all three hundred. Since it grows in length more than twenty-five centimeters.
But there are also the smallest, two or three centimeter. The Australian earthworms reach two and a half meters in size. Its color in the literal sense of the word gray-brown is raspberry.
Also, on each ring, or it is also called a segment, there are bristles. In our ordinary garden worms, as a rule, eight setae grow. They are classified as low bristle.
However, there are tropical, multi-bristle species of worms in which villi grow in dozens. The bristles help the worms crawl along absolutely all soil tubercles or burrow into burrows.
You can detect them by taking the worm in your hands and swiping your finger from back to front. But since it is difficult for an inexperienced person to determine where his butt is, you can simply gently move your hand along the body and back. You can immediately feel it. In one direction, the worm will be absolutely smooth, and, having drawn in the opposite direction, will be rough.
Anyone who has ever taken a worm in their hands knows that it is all covered with not very pleasant mucus, which is vital for him. Firstly, the mucus helps the invertebrate to move freely in the ground. Secondly, since the worm has no lungs, it breathes through the skin. And thanks to the moisture located on the mucus, the body is saturated with oxygen.
Itself earthworm body consists of two groups of muscle tissue. They are longitudinal and transverse. The transverse muscles are located under the protective upper layer of the skin of the worm.
With their help, the worm becomes as long as possible. And stronger muscles are longitudinal. They contract, contract the body. So, now, lengthening, then shortening, the animal moves.
Earthworm refers to celiac animals. Therefore, he has a full-fledged closed circulatory system. Since their vital activity is active.
Muscles contract many times more often than in primary-celled worms. To do this, they need blood to provide the worm with all the nutrients and oxygen.
IN earthworm structurethere is a pair of blood vessels, one of them is called the dorsal, the second abdominal. Ring vessels connect them together. Blood flows through them from back to front, and vice versa.
In each ring, or as it is also called a segment, there is a pair of tubes. The funnels at their ends open and excrement is removed through the bottom earthworm.This is the principle of the excretory system.
As for the nervous system, it is nodal. Its components are the abdominal nerve chain and the periopharyngeal nerve ring. These endings consist of fibers, and those, in turn, respond to the urges of the contracted muscles of the worm. Thanks to them, the worm can eat, purposefully move, multiply, and develop.
In the building earthworm organsthere are no those responsible for the sense of smell, touch, vision, sensation. But there are certain cells, they are located along the entire body of the invertebrate. With their help, the worm is oriented in the dark and impassable land.
Character and lifestyle
Charles Darwin also suggested the existence of intelligence in earthworms. Watching them, he noticed that pulling a dry sheet to his home, he turned it exactly the narrow side. Which facilitates the leaf through the dense, earthen hole. But spruce needles, on the contrary, take as a basis so that they do not bifurcate.
All day all rain life the worm painted by minute. He continually climbs the earth, makes moves, swallowing it. Digging a worm in two ways. He or, as already mentioned, swallows the earth, gradually moving forward.
In case the earth is too hard. And after leaving their biological waste. Or, shoves it with its sophisticated end, in different directions, and makes moves for itself. The passages are obliquely vertical.
Tech rain worm, fishing in the soil, pulls into his holes, for insulation, various leaves, veins from leaflets, thin pieces of paper and even shreds 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.
AND why earthwormsin huge quantities creep out to the surface. This means that he has nothing to breathe. This usually happens after heavy rains. The earth is clogged with moisture, and it does not have oxygen at all. Upon the arrival of cold weather earthwormgoes deep into the soil.
Earthworm Nutrition
The worm’s nutrition is fairly typical. Swallowing large quantities of land with food. For food, they are suitable for sluggish and slightly rotted leaves, mushrooms. But it should not have an unpleasant smell, otherwise the worm will not eat it.
It turns out that earthworms even build themselves whole storage rooms, and put food there by winter. They eat it only in case of critical need. For example, in winter timewhen the ground is completely frozen, and there can be no talk of any ground food.
Having sucked the food along with a lump of earth, through the throat, with muscle movements, then expanding his body, then narrowing, he pushes it to the back of the esophagus in the goiter. After, it penetrates the stomach. It is sent from the stomach to be overdone in the intestine, thanks to enzymes, it comes out to the surface with useful biomasses.
Making moves, and at the same time snacking, rain the worm need to crawl outperiodically to the surface to throw off the ground. At the same time, he adheres to the hole with his tail edge, as if holding onto it.
And after, there are always earthen slides. The soil processed by the worm is sticky. It dries up the note, and becomes small, with a match head with balls.
These balls are saturated with vitamins, enzymes, organic substances, which, as a result, kill all bacteria in the ground, prevent rotting, which is very important for plant roots. And they act on the composition of the earth as an antiseptic, disinfecting it.
Reproduction and longevity
Earthworms can be heterosexual, and hermaphrodites. All earthworms on the front third of their body have thickenings. They contain the ovary and testis. Hermaphrodites let in a seed into each other. Already ripened testicles, within ten pieces, are inseminated. And creep away in different directions.
When a female individual is already ready for reproduction, she approaches her partner and copulates. On it, something like a cocoon is formed, consisting of several dozen thickened segments.
It is divided by a kind of belt. All the nutrients necessary for brood enter this cocoon. After fertilization, the worm removes this burden from itself, it simply slides off the animal.
The edges on the cocoon, on both sides are quickly pulled together so that future offspring do not dry out before they are born. Then, within four weeks, small worms mature and bear.
Having been born, they creep where to where. And from the first days of their lives they begin active work on the processing of land. And already at the age of three months, grown up children reach the size of adults.
Another fact about earthworms is the ability to regenerate. If someone, or something, divides him into two halves. Over time, each of the halves will become a full-fledged individual. This is one of the methods of reproduction, but not by sexual means.
The role of the earthwormin agriculture is very important. Firstly, they saturate the soil with oxygen, so necessary for everything growing on it. With their moves, they help the roots to fully develop.
Moisture is evenly distributed, and the soil is well ventilated, loosens. Thanks to the constant movement of the earth, with the help of worms, stones are extracted from it.
Also, with their recycled adhesive residues, they glue the soil, preventing it from eroding. Well, and of course they fertilize the earth when they pull in leaves, insect larvae. It all rots and serves as excellent, natural bio-supplements.
givnost.ru
Variety of worms
Worms include groups of multicellular animals that have an elongated body and no skeleton. Habitats are, as a rule, moist soil, the sea and fresh water bodies. In size, they can vary from those that can only be detected under a microscope, to large forms, several meters long. In accordance with the shape of the body, there are: Flat, Round and Annelids. All types have three layers of the body. The embryonic layers - ectoderm, endoderm and mesoderm give rise to the development of all their tissues and organs.
The brightest and most famous representatives of flatworms are: planaria, hepatic fluke, pork and bovine tapeworms, echinococcus, schistosome, etc. Known annelids include: earthworm, small-bristle worms, leeches and misostomids. Round primitives are represented by all known roundworms, pinworms, rishts, trichinella, etc.
Despite the variety of existing types of worms, their types, structural features, methods of reproduction, nutrition, habitats, etc., there are a considerable number of similarities characteristic of all of them. For example, flatworm breathing, divided into aerobic and anaerobic, depending on the habitat, is also characteristic of the other two types.
Flatworms
The system of organs of flatworms is represented by a number of basic structural components, united by common functional features and by type of structure. The main systems include: respiratory, reproductive, excretory, muscle, nervous and integumentary.
Earlier, a series of other taxonomic elements, characterized by worm-shaped forms, the absence of body cavities and considered to be invertebrates, were attributed to the class of ciliary primary whales.
The body shape of any type has a bilaterally symmetrical shape, in which the head and tail ends are slightly flattened at both ends, but in large species, flattening is very pronounced. The system of organs of flatworms for respiration and blood circulation is absent. The cavity in the body does not develop, but this is true for all representatives, except for tapeworms and flukes on certain life cycles.
The structure of the integument
Acquaintance with muscles
The muscle tissue of flatworms is represented by a muscular sac, which lies under the epithelium. It consists of a number of layers of muscle-type cells that are not divided into muscles. However, some differentiation is observed in the areas of the pharynx and reproductive system. The outer part of the cells of the muscle layers are oriented transversely, and the inner ones along the rear-front axis of the body. The external musculature is called the annular layer, and the internal - the longitudinal muscular layer.
Breathing methods
All groups of flatworms are characterized by the presence of a pharynx, which leads to the intestine. The exception is cestode-shaped and tapeworms. This intestine opens into the parenchyma, intended for digestion, blindly closes and is connected with the outside world only through the mouth opening. Some large turbellaria have anal pores, however, this is an exception only for some species. Small forms are characterized by the rectum, and large forms (planaria, trematode) can be branched. The pharynx is located on the surface of the abdomen, often it can be found in the middle or closer to the back of the body. In some groups of worms, the pharynx moves forward.
Features of the nervous system and sensory organs
Characterizing the nervous system of the planar primary and fourth, it is worth noting that they are characterized by the presence of nerve nodes located in front of the body, and there are also ganglia of the brain and nerve columns branching from them, which are connected by jumpers. Sensitive organs include individual skin cilia, which are processes of nerve-type cells. There are free-living species that have special pigment-sensitive eyes sensitive to light. Such organs serve as a primitive adaptation to a sense of balance and allow you to see, albeit primitively.
Highlight system
Flat type worms are inherent excretory system, which takes the form of protonephridia. With their help, the process of osmoregulation and metabolism proceeds. The allocation system takes the form of channels that branch and are combined into 1-2 channels. Initially, these are star-type cells, which branch out into the tubules and open a lumen for the passage of a bundle of flagella. Merging, the tubules form a larger structure and are excreted in the form of excretory pores on the surface of the body. Such excretion systems are called protonephridial. Dangerous to the life of the worm metabolic products are excreted together with fluids through the aforementioned protonephridia, as well as with the help of special parenchyma cells - atrocytes, which play the role of "storage kidneys".
Reproduction
- Germaria - is actually the ovary. Produces eggs that are poor in yolk, but capable of development.
- Vitellarium - sometimes called yolk, it produces abortive-type eggs, they are rich in yolk.
These composite reproductive systems form complex, or exolecitic, eggs. The common membrane may contain one egg or a certain number of yolk balls secreted by the glands of the accessory type.
Conclusion
Summing up the above text, several conclusions can be drawn, among which the most significant are: the breathing of flatworms is carried out by the surface of the whole body, predominantly flatworms belong to predators, there is a muscular sac, the cover of the body is represented by a tegument, most relate to hermaphrodites and only a few of them are dioecious.
fb.ru
Annelids have the following aromorphoses: 1. There was a dismemberment of the body into segments (metamers) with repeating sets of internal organs. 2. A secondary cavity appeared - a whole having its own mesoderm lining. 3. A further complication of the nervous system occurred: the concentration of nerve cells on the abdominal side in each segment (the abdominal nerve chain was formed), a significant increase in the cerebral ganglia (nodes) (supraglottic, submaryngeal nerve ganglia, periopharyngeal ring). 4. There was a closed circulatory system, providing fast transport of substances throughout the body. 5. Respiratory organs appeared, increasing the respiratory surface and the intensity of gas exchange. 6. Has become more complicated digestive system: there was a differentiation of the middle intestine into departments, which led to a phased digestion process. 7. Formed parapodia - limbs for movement. 8. There was a further complication of the excretory organs: a metanephridial multicellular excretory system was formed.
Earthworm – Lumbricus terrestris (type Ringworms, class Little-worms, Lumbricidae family) lives in moist, humus-rich soil. It feeds on organic matter, passing land through the intestines with plant debris. C. Darwin also noted the beneficial effects of earthworms on soil fertility. Pulling the remains of plants into minks, they enrich it with humus. Paving moves in the soil, they facilitate the penetration of air and water to the roots of plants.
Earthworms are active in the warm season. In winter, they hibernate. Frosts instantly kill worms, so they must dig deeper into the ground, where low temperatures do not penetrate. In the spring, when the temperature reaches a suitable value and the earth is saturated with rainwater, the mating season begins for them. They breed very quickly, producing about a hundred young worms per year. In summer, worms are not so active. Food - dying plant debris - is very small at this time, and the soil is devoid of moisture, which can cause the death of worms. The autumn period is again characterized by the activity of worms. At this time, the reproduction of offspring begins again, which lasts until the onset of winter.
Earthworms live relatively long. Some manage to live about a decade, 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. Back side more rounded, it is darker, the dorsal blood vessel shines through her skin. Ventral side somewhat flattened and more light colored. The front end of the body is thicker and darker colored. The body consists of rings - segments. In an adult worm, their number reaches 200. In the region of 32-37 segments of the body is girdlerich in mucous glands. External segmentation corresponds to the separation of the body cavity by partitions into separate chambers and the segmented (i.e. in each segment) arrangement of a number of internal organs. On each segment on 8 bristles (they are easy to detect if you drag your finger along the body of the worm in the direction from the rear end of the body to the front). Setae arranged in four pairs on the sides of the segments. Clinging to them for uneven soil, the worm moves forward with the help of the muscles of the skin-muscular sac.
Veils. Earthworm body is covered skin and muscle bag. He is educated cuticlesingle layer epithelium and two layers of muscles - the outer roundabout and internal longitudinal. The worm skin epithelium is rich mucous membranes glandswhich produce slime, covering the entire body of the worm and protecting it from drying out. Mucus also facilitates crawling in minks, reducing friction on the soil.
The movement of the earthworm. When the worm crawls, waves of muscle contractions run through its body, and 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 stretch and at the same time become thinner, then contract and become thicker. As a result of such alternate stretches 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 to it; after this, the posterior end of the body remains in place, and the head end is pushed even further forward, and thus the worm continues to move forward (it is convenient to observe it by letting the worm crawl along the paper spread out on a table).
Body cavity. Inside the skin-muscle bag in annelids is located secondary cavity body, or whole. This body cavity is not limited by muscles, like roundworms, but has its own epithelial (coelomic) lining, i.e. the inner side of the longitudinal muscles is lined with epithelium of mesodermal origin, and the epithelial lining is also on the side of the intestine lying in the body cavity. Due to the coelomic epithelium, internal bilayer transverse partitions between the segments are formed - dissidents. The secondary cavity is divided into chambers, in each segment there is a pair of coelomic sacs. Coelomic fluid is under pressure and plays a role hydroskeletontherefore the worm is resilient to the touch.
Digestive system consists of front, middle and back guts. Mouth located on the second segment from the ventral side of the body. Anal hole
type of ringworm earthworm
- at the rear end of the body, it looks like a small gap. Due to the nutrition of rotting plant residues and humus, the digestive system has a number of features. Her anterior section is differentiated into muscular throat, esophagus, goiter and muscle stomach. A fold has formed on the upper intestine to increase the suction surface tiflosol(tiflosolis). Please note: differentiated sections of the anterior intestine - pharynx, esophagus, goiter, stomach - were absent in previous types of worms.
Breath. An earthworm breathes 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 worm’s body does not dry out, but excessive moisture (for example, very moist soil after rain) is equally disastrous for them.
Circulatory system closed, that is, blood moves through the vessels, not spilling into the body cavity. The movement of blood is determined by the pulsation of large vessels, mainly around the esophagus. These are kind of hearts. Blood provides the supply of all organs and tissues with nutrients, transporting them from the intestines, and oxygen, which enters the capillaries of the skin from the external environment. By spinal vessel blood moves from the rear end of the body to the front, and along abdominal vessel - in the opposite direction. The blood of the earthworm is red. An iron-containing protein close to hemoglobin of vertebrates and transporting oxygen is contained in a dissolved state in blood plasma, and red blood cells are absent.
Nervous system more complex than flat and round worms. It consists of neural pharyngeal ring with ganglia and abdominal nervous chains. This is the so-called nervous system. stair type. Pharyngeal doubles ganglion fulfills the functions of the brain and is developed more than sub-pharyngeal. The neural chain originates from the subpharyngeal node and is segmented pairs of nerve nodesconnected by honey transverse and longitudinal commissions. From the ganglia nerves depart to various organs. The sensory organs are poorly developed in the earthworm: eyes and tentacles are absent, but numerous sensory cells and nerve endings are embedded in their skin.
Excretory organs represented by segment (i.e. in each segment) arranged paired metanephridia. They look like crimped tubes, begin in the body cavity with a funnel with cilia. A channel departs from the funnel, which penetrates the transverse septum, passes into the cavity of the next segment. The final section of methanephridia has an extension - uric bubble, which opens outward on the side of the worm’s body (i.e., in each segment, a pair of very small excretory holes). In addition to methanephridia in the selection involved chloragogenic cellscovering the surface of the intestine with a thin brown-yellow coating. Chloragogenic cells accumulate excretion products. Filled with metabolic products, these cells die, and their contents enter the body cavity, from where it is removed by metanephridia.
Reproduction. Earthworms hermaphrodites. The reproductive organs and the girdle can be considered only during the breeding season - in the spring. To male
type of ringworm earthworm
reproductive system two pairs of testeslocated in segments 10 and 11, four vas deferensthat merge in pairs and open outwards doubles male sexual holelocated in 15 segment. The female reproductive system includes couple ovarieslocated in 13 segments oviductsthat open outward in the 14th segment a couple female genital holes. In segments 9 and 10 there are two pairs seed box, each of which opens outward with an independent hole.
Earthworms reproduce sexually. Cross fertilization, in a cocoon. Two worms meet, closely entwine each other with bodies, are attached to each other with the ventral sides and exchange sperm that enters the testicles. After that, the worms disperse. Further, the girdle forms a mucous sleeve, eggs are laid in it. When the clutch moves through segments containing the testicles, the eggs are fertilized with sperm belonging to another individual. The clutch is discharged through the front end of the body, compacts 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 the earthworm, a whole worm is restored.
Questions for self-control
What are the ringworm aromorphoses?
What is the classification of annelids?
What is the systematic position of the earthworm?
Where do earthworms live?
What shape do earthworms have?
What is the body of the earthworm covered with?
What body cavity is typical for an earthworm?
What structure does the digestive system of the worm have?
What structure does the circulatory system of the worm have?
What structure does the excretory system of the worm have?
What structure does the worm nervous system have?
What structure does the reproductive system of the earthworm have?
How does an earthworm breed?
What does an earthworm mean?
type of ringworm earthworm
Fig. Earthworm, its moves in the ground and movement.
Fig. The internal structure of the Earthworm.
1, 16 - the intestine; 2 - partitions; 3 - epithelial lining of the secondary cavity of the body; 4 - dorsal (back) blood vessel; 5 - annular blood vessel; 6 - skin-muscle bag; 7 - cuticle; 8 - skin epithelium; 9 - whole; 10 - methanephridium; 11 - eggs; 12 - ring muscles; 13 - longitudinal muscles; 14 - ventral (abdominal) blood vessel; 15 - abdominal nerve chain.
type of ringworm earthworm
Fig. The structure of the front end of the body of the Earthworm.
Prostomy is a protrusion of the upper part of the first segment, covering the mouth. Peristomy is the name of the first segment of the body.
type of ringworm earthworm
Fig. The structure of the Earthworm.
A is the head end; B - internal structure; B - the nervous system.
1 - mouth opening; 2 - male genital opening; 3 - female genital opening; 4 - belt; 5 - pharynx; 6 - the esophagus; 7 - goiter; 8-stomach; 9 - intestines; 10 - dorsal blood vessel; 11 - annular blood vessels; 12 - abdominal blood vessel; 13 - methanephridia; 14 - ovaries; 15 - testes; 16 - seed bags; 17 - testicles; 18 - periopharyngeal nerve node; 19 - periopharyngeal nerve ring; 20 - abdominal nerve chain; 21 - nerves.
type of ringworm earthworm
Fig. A longitudinal section of the body of the Earthworm.
1 - mouth; 2 - pharynx; 3 - the esophagus; 4 - goiter; 5 - stomach; 6 - intestine; 7 - periopharyngeal ring; 8 - abdominal nerve chain; 9 - "hearts"; 10 - dorsal blood vessel; 11 - abdominal blood vessel.
Fig. Reproduction of the Earthworm.
1 - mucous coupling; 2 - cocoon; 3 - exit of young worms from the cocoon.
type of annelids
Fig. The structure of the Nereida Polychaete worm.
type of annelids
Fig. Appearance Medical leeches.
Animals, suborder earthworms. The body of the earthworm consists of ring-shaped segments, the number of segments can reach up to 320. Moving, earthworms rely on short bristles that are located on the segments of the body. When studying the structure of the earthworm, it is clear that, unlike a whipworm, his body looks like a long tube. Earthworms are common throughout the planet except Antarctica.
Appearance
Adult earthworms are 15 to 30 cm long. 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 body of the worm 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 is convex and darker than the ventral. About where the front of the body ends, the worm has a bulge called the girdle. It contains special glands that secrete a sticky liquid. When propagating, an egg cocoon is formed from it, inside of which worm eggs develop.
Lifestyle
If, after the rain, you go out into the garden, you can usually see small heaps of earth thrown out by earthworms on the path. Often the worms themselves crawl along the path. Precisely because they appear on the surface of the earth after rain, they are called rain. These worms crawl to the surface of the earth also at night. Typically, an earthworm lives in humus-rich soil and is not common on sandy soils. He also does not live in the swamps. Such features of its distribution are explained by the way of breathing. The earthworm breathes 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 is suffocating there. Even faster, he dies in dry soil: his skin dries out and his breathing stops. In warm and humid weather, earthworms stay closer to the surface of the earth. During prolonged droughts, as well as in the cold period, they creep deep into the ground.
Moving
The earthworm moves by crawling. At the same time, he first retracts the front end of the body and clings to the roughness of the soil with bristles located on the abdominal side, and then, contracting the muscles, pulls the rear end of the body. Moving underground, the worm makes its own moves in the soil. At the same time, he pushes the ground 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 through the anus at its mink. So on the surface of the earth are formed long "shoelaces" of earth and lumps that can be seen in the summer on garden paths.
This method of movement is possible only with well-developed muscles. Compared to hydra, the earthworm has more complex muscles. She lies under his skin. The muscles together with the skin form a continuous musculocutaneous sac.
The muscles in the earthworm are located in two layers. Under the skin lies a layer of ring muscles, and under 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 ring muscles contract, on the contrary, the body becomes thinner and longer. Contracting alternately, both layers of the muscles cause the worm to move. Muscle contraction occurs under the influence of the nervous system, which branches out in muscle tissue. The movement of the worm is greatly facilitated by the fact that there are small setae on its body from the ventral side. They can be felt by running a finger soaked in water on the sides and on the abdominal side of the body of the worm, from the posterior end to the anterior. 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 lowers and rises through its earth passages.
Nutrition
Earthworms feed mainly on semi-decayed plant debris. They drag, usually at night, into their mink leaves, stalks, and more. Earthworms also feed on humus-rich soil, passing it through the intestines.
Circulatory system
The earthworm has a circulatory system that the hydra does not have. This system consists of two longitudinal vessels - the dorsal and abdominal - and the branches that connect these vessels and carry blood. The muscular walls of blood vessels, contracting, drive blood throughout the body of the worm.
The blood of the earthworm is red, it is very important for the worm, as for other animals. With the help of blood, the connection between the organs of the animal is captured, metabolism occurs. Moving through the body, it carries nutrients from the digestive system, as well as oxygen that passes through the skin. At the same time, blood carries carbon dioxide from the tissues into the skin. Various unnecessary and harmful substances formed in all parts of the body, together with blood, enter the organs of excretion.
Irritation
The earthworm has no special sensory organs. He perceives external irritations with the help of the nervous system. The earthworm has the most developed tactile sense. Sensitive, tactile nerve cells located over the entire surface of his body. The sensitivity of the earthworm to all kinds of external irritation is quite high. The lightest vibrations of the soil make it quickly hide, crawling into a hole or into deeper layers of the soil.
The value of sensitive skin cells is not limited to touch. It is known that earthworms, without special organs of vision, nevertheless perceive light irritations. If a worm suddenly illuminates the worm at night, it quickly hides.
The response of the animal to irritation by the nervous system is called a reflex. There are different kinds of reflexes. The contraction of the body of the worm from touching, its movement in sudden light with a flashlight 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 found that earthworms can easily distinguish the leaves of the plants they feed on by smell.
Breeding
Unlike hydra, an earthworm propagates exclusively through sexual contact. Asexual reproduction he doesn’t. Each earthworm has male organs - the testes, in which the livestock develops, and the female genital organs - the ovaries, in which the eggs are formed. The worm lays its eggs in a mucous cocoon. It is formed from a substance secreted by the worm’s girdle. In the form of a sleeve, the cocoon slides off the worm and is pulled together at the ends. In this form, the cocoon remains in the earthen mink until young worms leave it. Cocoon protects eggs from dampness and other adverse effects. Each egg in the cocoon is divided many times, as a result of which the tissues and organs of the animal are gradually formed, and finally, small worms, similar to adults, emerge from the cocoons.
Regeneration
Like hydrams, earthworms are capable of regeneration, in which lost parts of the body are restored.