The shape of the spindle, and in cross section it's round. Hence the type. The body of roundworms is not divided into segments.

Evolutionary neoplasm - primary cavity body, or pseudo-goal. The pseudocoel is filled with intercellular fluid and contains internal organs. The fluid serves as a hydroskeleton, gives the body elasticity and facilitates the exchange of substances between organs.

The body of roundworms is made of three layers. The top layer is the cuticle, it acts as an exoskeleton. The cuticle also protects the body from damage.

The second layer consists of epithelial cells (hypodermis), where metabolic processes. From the inside, a layer merges with the hypodermis - muscle cells.

The muscles of roundworms are smooth. In total there are four longitudinal single-layer muscles. They allow roundworms to crawl by bending their bodies.

Due to the presence of smooth muscles, roundworms can move very quickly and energetically. For example, large nematodes can fit into fairly narrow openings.

Differentiated organ systems of roundworms

Roundworms have a total of five organ systems. Only the circulatory and respiratory systems are missing. During evolution, these systems appeared in annelids.

The digestive system is represented by a through tube. At the anterior end of the body there is a mouth opening surrounded by lips. The digestive tube ends with the anus, which is also an evolutionary neoplasm.

Excretory system roundworms include skin glands With excretory duct.

Roundworms have special organs - phagocytic. They retain insoluble metabolic products and foreign bodies that enter the body.

As for the reproductive system, roundworms are dioecious. The female genital organs are paired: ovaries, oviducts, uterus and genital opening. The male has unpaired genitalia, including the testis and vas deferens.

The nervous system of roundworms consists of a peripharyngeal nerve ring and six nerve trunks. The nerve trunks are connected by jumpers. As sensory organs, roundworms have tactile tubercles and chemical sense organs.

Where do roundworms live?

Roundworms live in a wide variety of environments. The life of some species takes place in the wild. They live in soil and water (regardless of its salt content).

Let's read the information .

Roundworms(primocavity or nematodes) - three-layered multicellular animals with a bilaterally symmetrical body, having a cylindrical shape with a circular cross-section in cross section.

The group was first identified by the German zoologist K.A. under the name Nematoidea (Nematodes).

Today, most scientists distinguish 2 classes in the Nematode phylum (Adenophorea and Secernents).

Structural features

1. have a cylindrical or spindle-shaped body. In cross section it is round (hence the name of the type).

2. there is no body segmentation.

3. have an outer cuticle, which performs the function of an exoskeleton (protects against mechanical and chemical influences).

4. have a body cavity - a separate space between the body wall (skin-muscle sac) and internal organs (in flatworms this space is filled with loose fiber - parenchyma).

Roundworms are believed to have evolved from a group of flatworms.

Aromorphoses, which contributed to the appearance of roundworms:

• the appearance of a primary body cavity (the second name for the type is primary cavity)
• progressive development nervous system(formation of ganglia, peripharyngeal nerve ring, dorsal and ventral nerve trunks)
• appearance posterior section intestines and anus
• appearance of excretory opening
• the appearance of four muscle strands, which allowed bending when crawling
• emergence of dioecious reproductive system And internal fertilization

Footnotes

Ascariasis– an invasive disease of humans and pigs caused by roundworms. Symptoms: mainly indigestion, exhaustion.

Trichinosis– an invasive disease of humans and animals (pigs, dogs, cats, ruminants, rodents, etc.) caused by trichina.

Dracunculiasis– an invasive disease of humans and animals caused by guinea worm (affects the subcutaneous tissue).

Trichinella(Trichina) is a worm of the class of nematodes.

Hookworm- a worm of the class of nematodes.

Rudolphi Asmund Karl (1771 – 1832) – German naturalist, zoologist and botanist.

Literature used:

1.Biology: complete guide to prepare for the Unified State Exam. / G.I. Lerner. – M.: AST: Astrel; Vladimir; VKT, 2009

2.Biology: Animals: textbook. for 7-8 grades. general education Institutions. – 7th ed. – M.: Education, 2000.

3.Biology for those entering universities. Intensive course / G.L.Bilich, V.A.Kryzhanovsky. – M.: Onyx Publishing House, 2006.

4.Biology: textbook / reference manual / A.G. Lebedev. M.: AST: Astrel. 2009.

5.Biology. Full course of secondary school: training manual for schoolchildren and applicants / M.A. Valovaya, N.A. Sokolova, A.A. Kamensky. – M.: Exam, 2002.

Internet resources used:

Nematode plant diseases

The phylum roundworms, or nematodes, presumably originated from turbellarians. Evolving, this class acquired a peculiar structure, which is strikingly different from the structure of flatworms. This fact forces us to consider nematodes as a separate specimen of the animal world. Since the relationship of nematodes with groups higher up has not been proven, they are considered a lateral branch of the family tree of animals. This phylum has more than 10,000 species of organisms.

The general characteristics of roundworms focus on external structure. From a medical point of view, roundworms are of great interest, since only they contain forms that are pathogenic for the human body.

This peculiar structure allows them to crawl freely, bend their body in different sides. Characteristics of the type of roundworms show that they lack the circulatory and respiratory systems. These organisms breathe through the cover of their body.

Digestive system

The digestive system of roundworms resembles a tube, that is, it is continuous. Starting with oral cavity, gradually passes into the esophagus, then into the anterior, middle and hindgut. The hindgut ends at the anus on the other side of the body.

Many representatives of roundworms have a terminal oral opening, in some cases it is shifted to the ventral or dorsal side.

Selection system

Breeding system

The nematode has reproductive system with a tubular structure. These organisms are heterosexual. Males have only one tube, different areas which perform various functions. The narrowest section is the testis, which, in turn, is divided into two sections - reproduction and growth. Next is the vas deferens, and the channel for the eruption of the seed.

Females have a 2-tube reproductive system. One tube, ending in a dead end, plays the role of an ovary; it is filled with germ cells capable of reproduction. This organ flows into a larger section, which plays the role of the oviduct. The largest section of the female reproductive system is the uterus. The two uteri, connecting to each other, form the vagina, access to which is open on the front of the body.

Females and males differ significantly in external signs. Males are usually smaller and rear end Many bodies are twisted towards the belly. In most species of nematodes, reproduction is viviparous - females carry an egg in the uterus until the larvae hatch from it.

Nervous system

The nervous system of roundworms is a nerve ring, from which nerve trunks branch. Of these, the ventral and dorsal trunk are the most developed.

Life cycle

Nematodes in the human body cause diseases called nematodes, many of which pose a serious threat to health. There are classes of roundworms that are most common among humans.

Roundworms

The egg that the roundworm produces ends up in a person with unwashed vegetables or berries, on which they fell, respectively, from the ground. The larva hatches from the egg and begins its journey along to the human body. It has the ability to pass through the intestinal walls, penetrates the blood vessels, and enters the liver, atrium and lungs with the blood flow. To develop safely, roundworms need oxygen, so the larvae migrate to the pulmonary alveoli, and from there to the bronchi and trachea.

The waste products of roundworms are very toxic, so patients may experience severe headache, constant fatigue, outbursts of irritability. In addition, ascariasis often provokes intestinal obstruction.

Very common helminths, small nematodes white. The size of males is no more than 3 mm, females reach a length of 12 mm. Infection with pinworms can occur due to non-compliance with hygiene rules, so children who visit kindergarten. The patient is tormented severe itching, he scratches the skin until it bleeds, pinworm eggs remain on the hands and under the nails, after which they are transferred to household items and food.

The structure of roundworms of this species is such that they cling tightly to the walls of the intestine and feed not only on its contents, but also on blood. The toxins released by pinworms can cause headaches, insomnia, fatigue and dizziness, as well as allergies.

By blood vessels the crooked head enters the heart, from there to the lungs, upper respiratory tract and throat. Together with saliva, they penetrate the esophagus, then the stomach, the destination being the duodenum. This type of nematode can enter the body in two ways - either with contaminated food and water, or by entering through skin. Soon after entering the body, the patient begins to experience pain in the duodenum, indigestion, fatigue, headache, depression, impaired memory and attention are observed. In the absence timely treatment this disease can be fatal.

How to combat the penetration of nematodes into the body? Preventive measures are quite simple, but nevertheless require strict adherence:

• do not neglect the rules of personal hygiene, wash your hands as often as possible hot water with soap;
• carefully process all vegetables, fruits and berries before eating (to protect yourself, you need to immerse them in boiling water for 3 seconds, or for 10 seconds in hot water, then rinse thoroughly with cold water);
• It is not recommended to use human and pig feces that have not undergone the composting process as garden fertilizer;
• cut nails of adults and children as often as possible, change bed linen and underwear daily.

Nematodes are an integral part of nature, and it is impossible to eliminate them, but with the help of simple measures you can protect yourself from their invasion of the body.

Type Roundworms: structural features. The name says a lot about the structure of representatives of this type - in cross section they have a round outline. Their body is spindle-shaped and narrowed at the ends; the head can be clearly seen at the anterior end. The type of body symmetry is bilateral.

Their body consists of a skin-muscular sac, which is separated from internal organs primary cavity, or pseudocoelom. The skin on top is covered with a dense layer of cuticle, which is produced by the epithelium of the outer integument.

Roundworms: structure of the digestive system. Digestive tract this group of organisms is cross-cutting. The mouth opening is located at the anterior end of the body and is surrounded by lips and muscle tissue. It leads into the muscular pharynx, which is used for active absorption of food. Food then enters the midgut and then the hindgut. Metabolic products are excreted through the anus in females, or into the cloaca in males.

Roundworms: respiration and excretion. There are plenty of roundworms. This includes the large single-celled cervical gland. Metabolic products accumulate in cavity fluid, after which they move into the gland through two longitudinal lateral channels and are brought out. The cervical gland has a separate excretory opening that opens into the abdominal gland. Some metabolites, such as ammonia, are excreted directly through the body wall.

As for breathing, organisms do not have organs specifically designed for this. Oxygen is absorbed by intestinal tissues. In the event that you have to live in conditions oxygen starvation, roundworms can switch to anaerobic respiration.

Roundworms: reproduction. Representatives of this group belong to dioecious organisms. At the same time, quite noticeable sexual dimorphism is observed - in the male the rear end is bent to abdominal part bodies.

The female reproductive organs are represented by the ovaries, uterus and oviducts. The male has testes, vas deferens and an ejaculatory duct. The male's sperm are inserted into the female's vagina through. Interestingly, the sperm do not have flagella, have limited mobility and are amoeboid in shape.

How do Roundworms differ from Flatworms?? In fact, the differences between these two types of animals are quite noticeable. To begin with, it is worth mentioning the shape of the body - in cross section Flatworms have a flattened body. Another significant difference is the primary body cavity, which is absent in representatives of Flatworms. In addition, Nematodes already have a through digestive system. It is worth noting that flatworms are hermaphrodites.

• feeling of heaviness in the lower abdomen;
• nausea and vomiting;
• general malaise;
• frequent diarrhea.

• the helminth has a pale pink tint;

• female body length – 20-40 mm, male – 15-20 mm;
• Dioecious individuals reproduce sexually.

For gastrointestinal infection and ascaris penetration into the liver clinical symptoms is expressed in the following manifestations:

1. Abdominal pain, accompanied by bouts of vomiting and constant nausea.
2. Diarrhea occurs with bloody discharge in feces.
3. Pressure on the liver and bile ducts promotes the formation of obstructive jaundice.
4. Lack of appetite and uncontrolled weight loss.

The symptoms of pulmonary ascariasis are more problematic to recognize, since clinical signs mistaken for other diseases respiratory system, for example, bronchitis, pneumonia, etc. The presence of helminths in the lungs is accompanied by the following symptoms:

• dry paroxysmal cough and chest wheezing;
• dyspnea;
• low-grade body temperature.

Undiagnosed ascariasis in the lungs leads to the development of bronchial asthma.

When roundworm penetrates the brain, a person experiences severe headaches, epileptiform seizures and convulsions occur, and there is pronounced neurosis and depression.

Important! All clinical manifestations require careful diagnostic examination and related medical effects.

• Piperazine;
• Albendazole;
• Vermox, etc.