Round worms have no system of organs. General Characteristics of Round Worms

In the kingdom of animals. More than 80 thousand species are described, but in reality, they are much more. Judging by the number of their appearance, fitness to the environment and good survival, specialists concluded that this population has more than a million representatives. Nematodes adapted to habitat in different sources, such as seas and reservoirs, soil, etc. Their presence in the human body and animals causes a huge damage, and the worms themselves are capable of causing various diseases.

Round Worm Digestion System

Nematodes or simply speaking round worms, in contrast to their relatives, endowed with anal hole. The intestine passes through all Gelming Taurus, taking the kind of straight tube. Food originally falls into the throat (initial part of the intestines), which is represented by muscular walls.

As a rule, breathing at round worms occurs through all the Taurus, since there is no blood supply system. Accordingly, there is no need to transfer oxygen to all organs. The energy obtained at the expense of food is allocated due to the cleavage of glycogen - substances having an organic nature.

Selection system

Neurological map of nematode

Companies and chemical perceptions are well developed. No sense organs in nematode are absent.

System of fertilization and reproduction

Cycle of vital activity nematodes

Round worms during their existence passes five stages of development: four of them are larvae and one adult. All transitions are associated with environmental change or migration from one owner to another.

Biohylminty

The main carriers are people, man-like monkeys and other mammals. Tinged biohylminths with various bloodsowing insects.

Phillaria goes into the bloodstream only when the carrier is most active. In the case of mosquitoes, it is evening and night time. At the blind way - the morning and daytime. When transferring the phillarium with midges or hoopers - their output does not have a specific period, and depends only on humidity.

Main types of round worms

1. Wucherria Banctofti. : People and monkeys focuses in bloodary arteries and lymph nodes. Leads to stagnation of blood and lymphs. It is also the reason for the appearance of elephant and allergyization. The main carrier is a mosquito.
2. Brugia Malayi. : The final owners are people, some types of monkeys, Feline Fabric. Pathogenicity and concentration is similar Wucherria Banctofti.. Also transferred to mosquitoes.
3. Oncocerca Volvulus. : It is transferred to midges, and the Helmint carrier is a person. Concentrated in the body under the skin of the head, chest, hands and legs. Promotes the formation of painful nodules. Concentrating in the area of \u200b\u200bthe organs of vision - may cause blindness.
4. Loa Loa. : Localizes under the skin and mucous membranes in humans and monkeys, forms painful nodules and jacks. It is transferred to blind ways.
5. Mansonella : focuses in the body of the carrier, which are people, in the subcutaneous fat layer, bowlaries of the intestine and under serous shells. It is transferred by the hoopers.

It is also worth mentioning the most common types of round worms.

Askarida

Askarida

Askarida

Round worms - three-layer unintended animals with bilateral (dummy) symmetry, the body of which is covered with a skin-musical bag, and the space between the internal organs is filled with liquid.

Systematics.The type of round worms is divided into classes: gastrotrikhi, nematodes, hair, scrapers, proofrs. The most famous and important is the class of nematodes, which will be mainly discussed.

Body shape. Most round worms have a strongly elongated, round body in cross section. The ends of the body are usually pointed. However, spherical, lemon-shaped and bean forms come across. It is customary to distinguish the esophageal department, the middle and tail of the body.

Skin-muscular bag. Outside, nematode body is covered with a dense multilayer cuticle. Most often it has a collected structure. This layer has an important reference and protective value.

Under the cuticle there is a nematode nematode itself - a cellular or sycitial epithelium, which is called the hypoderma. The hypoderma forms on the spinal and abdominal side, as well as on the sides, longitudinal thickens are hypodermal rollers. In the spinal and abdominal rollers there are large nervous trunks, and in the side - channels of the excretory system. Hydrometer plays an important role in nematode breathing.

Musculature in nematodes is represented by one layer of longitudinal muscle cells adjacent to the hypoderma. Most often, the muscle layer is divided into the dorsal and abdominal ribbons that ensure the mobility of the body of worms. There are also smaller muscle groups that ensure the mobility of internal organs - esophageal, intestinal, anal, vulvar, spcolar and some others. These muscles go from the body wall to the relevant authorities.

Traffic. Due to the device of the muscular system of motion, nematodes are extremely imperfect. These animals can only lengthen or shorten the body if all muscles act at the same time; Ring-shaped folded if only one muscle and a serpentine bending, if the muscles work alternately. Some soil nematodes are capable of jumping a few millimeters.

Body cavity. In contrast to flat worms, in which the space between the body wall and the internal organs is filled with parenchyma, in round worms, this space forms a cavity filled with liquid. This cavity does not have its own walls and is limited to the muscle layer and internal organs. Such a cavity is called primary (synonyms: protocel, hematcell, schisocel). The primary cavity is filled with a liquid under significant pressure (high-strip tour) supporting the form of nematodes (reference function). In the liquid, the products of metabolism are accumulated, which are in the future are derived from the body (separation function).

Digestive system Nematode through and consists of three departments - the front, middle and rear.

The oven begins the oral hole surrounded by lips. In the oral cavity can be teeth, spear or stale. Behind the oral oily should be esophagus, the structure of which is quite varied. It can be direct or divided into departments. A number of species on the esophageal are bloating - bulbs methanpal and cardiac. Inside the cardiac bugly, a muscular crushing machine is often located, which homogenizes food. Between the bugles is noticeable with a small experiencing - Istimus - which is stuck with a nervous ring. The esophagus has cuticular liner. Some groups have esophageal glands that allocate enzymes.

The middle intestine is a single-layer epithelium tube. In this department, digestion and suction of food occurs.

The rear department of the intestine was removed from the inside of the cuticle and opened at the rear end of the body in females by anal hole, and the males in the cavity of the clock.

Selective system. In the esophageal part of the body there are one or two large cervical cages. These cells form one or two excretory channels, which stretch in the side rollers of the hypoderma along the entire body. In front of the front, two channels are connected to the unpaid duct, opening out the outlook sometimes. Many species have several so-called phagocytic cells that capture foreign substances from the strip fluid. These cells are probably associated with excretory channels.

Nervous system. The central part is the nervous ring - ishing the esophagus. The ring consists of nerve fibers and few nerve cells. Six nerve trunks to the organs of the esophageal part of the body are departed from the rings. Back Also stretch several trunks. At the same time they are located in the hypoderma. Typically, one or two nervous trunks are usually most developed. The close connection of the nervous system and the skin-muscular bag allows some authors to talk about the skin-muscular-nervous bag in nematode.

Sense organs. The nematodes are developed tangorotheptors (tactile), chemoreceptors (chemical feeling) and photoreceptors. Tangorotheptors are represented by papillary (small elevations on the cuticle) and bristles. These organs are located mainly at the head end, and in males and in the field of tail. Chemoreceptors are represented by amphids - peculiar recesses in the cuticle, which have a different structure. Amphids are located on the lips and on the sides of the head. Free-lived aquatic nematodes at the head end sometimes there are paired pigment spots equipped with a small lens. These are peculiar photosensitive organs.

Sex system. Nematodes - separation of organisms, while males are easily different from females (sexual dimorphism). Males usually smaller; Their tail hooks bent on the abdominal side.

The genital system of males and females has a tubular structure. At one species, the floor tube is unpaired ( monodelphic ), and others have a pair ( didelphne ). In the latter case, both tubes have a common output duct.

In males Usually monodelphic field system, it consists of glands - semennik, and output ducts - seeds and sophisticated Channel. Amebovoid spermatozoa is formed in the seed and fall into the docks. The seedweight canal along with the rear intestine open at the rear end of the body in Cloaca. Samtsov also has a composite device. It consists of one or two chitin spikul and rule. Curved sprockets for a groove knuckle are extended and fixed in the sexual female. In many species, males have paired wide extensions on the sides of the tail, forming semi Bursa. During the mating of the male worst the body of females.

Sexian sex system Usually didelphic. Each of the two genital tubes consists of ovaries, eggs and uterus. Both uterus lead into the total vagina, which opens with a sexual floor - vulva. Vulva is most often located in the front of the body.

A prerequisite for the manifestation of vital activity of nematode is the presence of drip-liquid moisture. Some species transfer long drying (10 or more).

Value. Inhabiting almost all biocenoses, nematodes are of great importance. They decompose dead organisms and take part in the soil formation. The high number of nematodes in the soil and bottom elevation causes their significant role in the food chains.

Morphology The scrapers are very peculiar. A characteristic feature of all the scrapers serves the presence of a trunk, armed with hooks and capable of drawing into a special vagina. Under the cuticle there is a hypoderma, which is syntsia with the system of cavities - lacun. Muscular cells also merge among themselves. Special muscles lead in motion of trull and some parts of the sexual system. There is muscular heavy - ligament which stretches from the vagina of the trunk to the rear end. Body cavity primary. The nervous system consists of one ganglia and nervous trunks departing from it. The senses are developed extremely weakly and are represented only by small tactile pains. There is no bowel of the scraper And the suction of food occurs through the covers.

Scrabs - separate animals. The seeds in males paired are usually compact and connected with the ligator. The glands from the glands, which merge into an unpaid seeds. This body opens and ducts of cement glands, whose allocations are cleaned by the sexual hole of the female during mating. Feed glands of females - ovaries - also pair and are located inside the ligance. However, the young females of the ovaries disintegrate on the lumps of eggs. The ligatus in some types of scrapes burst, and the eggs fall into the body cavity. It is output through a special complex apparatus. Special uterine bell swallow eggs; At the same time, mature are skipped into the uterus and in the future are outward, and immature pushes back to the body cavity.

Cycle of development The scraper occurs with the change of owners. Some eggs ripen in water. Others - on land. For the further development of the eggs "aquatic" species should get into the body of the intermediate owner - usually crustacean; Insects serve as "soil" species. In arthropods, a larva is formed - akantor which encapsulates and turns into akantella With screwed inwards. When eating such a segmental final owner of Akantella turns into an adult scraper. In the development cycle of "aquatic" types of scrapers, additional owners are often present - fish, eating racks and employees of food final owners - predatory fish.

Type Round Worms: Face Features. The name speaks quite a lot about the structure of representatives of this type - in the transverse section they have a round outline. The body is spit-shaped and narrowed at the ends, you can clearly see the head at the front end. Type of body symmetry - bilateral.

Their body consists of their skin-muscular bag, which are separated from the internal organs of the primary cavity, or a pseudo-feather. The skin on top is covered with a dense layer of cuticle, which is produced by the epithelium of external covers.

Round worms: the structure of the digestive system. The digestive tract of this group of organisms through. The river hole is located at the front end of the body and is surrounded by lips and muscle tissue. It leads to a muscular pharynx, which is used to actively suck food. Food further enters the middle, and then in the rear. The exchange products are displayed out through the anal hole in the females, or in Kloaku in males.

Round Worms: Breathing and Selection. Round worms pretty. This includes a large unicellular cervical iron. Metabolism products accumulate in a strip liquid, after which two longitudinal side channels are moved to the gland and outward. The cervical iron has a separate excretory hole that opens in abdominal some metabolites, such as ammonia, are output directly through the body wall.

As for breathing, there are no organisms specially designed for this. Oxygen is absorbed by bowel tissues. In the event that you have to live in oxygen starvation conditions, round worms can go to an anaerobic breathing type.

Round Worms: Reproduction. Representatives of this belong to the separation of organisms. In this case, there is a rather noticeable sexual dimorphism - the male rear end will be bent on the abdominal part of the body.

Family females are represented by ovaries, uterus and eggs. The male has seeds, seeds and a seedweight canal. Sperm of the male is introduced into the vagina of the females through which sperms do not have flavors, have limited mobility and an amoeboid form.

What circular worms differ from flat? 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 the cross section of flat worms have a flexible body. Another significant difference is the primary cavity of the body, which is absent among representatives of flat worms. In addition, nematode has a through digestive system. It is worth noting that flat worms are hermaphrodites.

Type of round worms - nematodes, very numerous and diverse. This type of living organisms combines almost 25 thousand species, combined in 31 detachments and 3 class.

They differ varieties and sizes of round worms - from several micrometers, up to several meters.

The most microscopic round worms have no more than 80 micrometers. The nematodes have a whole, non-dedicated to segments, a filamentous, or a spind-like body. Some worms have a barrel or lemon shape.

The body of round worms is a developed muscular system, and is covered with some kinds of smooth, in other - ringed nine-layer cuticle (skin). This gives them the opportunity to adapt to various habitat conditions: in water, in the ground, in the organisms of animals and humans.

Under the cuticle is the subcutaneous layer - hypoderma, which forms 4 chords around the body circumference:

• Dorsal - on the back.
• Ventral - on the trouser.
• 2 side.

The nervous system plays an important role in the activities of the internal nematode organs, so it is quite developed.

Inside the spinal and abdominal chord are parallel to the nerve fibers, connected by transverse jumpers, and collected into single nervous trunks. The first such jumper is located in the Harves of the Worm. From them, nerve fibers depart to the muscles and other organs. On the sides are the sensitive sensory nerves.

Sovereign organs at round worms are weakly developed, and are represented by bristles in the abdominal part of the Taurus. These bristles nematodes touches their environment surrounding their location, their location are small snaps of smell bodies. In large, in some extent developed types of worms have the simplest organs of vision.

Digestive organs

The digestive system from round worms on the structure resembles a through tube. It begins in your mouth, then follows the esophagus that goes into the front, then the middle intestine and ends with the rear intestine overlooking the abdomen from the caudal end of the worm.

The main features of round worms are that they have:

• Whole - hollow body space filled with non-connective tissue, like other worms, but liquid. Overall called the primary body cavity.
• The tail part of the intestine, concluded by anal hole.

The mouth of the circular worm leading in an easily expanding throat, is equipped with lips. In terms of the edges of the oral hole, the teeth are located with which the worm crushes food. The throat opens the entrance to the middle intestine and performs the function of a peculiar pump.

In the process of reducing the radial muscles of food, sucks in the intestine. Food movement also contributes to intra-palm liquid, forming pressure in the intestines.

Round worms have no blood formation, no respiratory system. But gas exchange is still happening. It can be said that the worms "breathe" with cuticle, or the cover of the body. The energy of nematodes is obtained from glycogen, which is split in the internal organs of the worm.

Disintegration products are derived from the body by primary fluid. The nutrient elements after processing in the intestine are also enrolled in this liquid, and it is delivered to other parts of the body.

The selection system is represented by two closed ducts, which are displayed on the abdominal nematodes. The decomposition products generated in the body of the circular worm fall into the fluid of the organizer, from it - into the ducts of the excretory system, from where and are output.

A feature of round worms can be called their sexual division into men's and women's individuals. The genitals from those and others have an elongated tubular shape. In the paired genital organs of the female presented by the dual uterus, as well as two ovaries with eggs, are formed from several tens of up to several thousand eggs, after a sematozoa formed by haggles, formed from the cuticle, will introduce spermatozoa, from the seed, to the sexy female gap.

Systematization of round worms still remains open. Initially, all worms (round, flat, collided) were combined into one type - worms. In this systematics, class Round worms was divided into two subclasses :

• Adenophorea (Adenophorea) ;
• SECERNENTEA .

The difference in subclasses was available or absence of phasemid - tactile bodies. After combining round worms in a separate type group, a classification was proposed. six classes :

• Nematoda (nematoda) ;
• Brohruche (Gastrotricha) ;
• KINORINCHI) ;
• Hair (Gorciiacea) ;
• Rotatoria (Rotatoria) ;
• Scrapers (Acanthocephala) .

Subsequently, the broxes, proofrs, hairstyle, scrapers were highlighted in separate types, and the cicloniralia's film centers were classified. The class of nematodes or, in fact, round worms were also revised. Modern systematics (2011) stands out three grades round worms :

• Chromadorea (Chromadorea) ;
• Enoplea (Enoplea) ;
• Dorylaimia (Dorylaimea) .

Fig. 1. Human Askarida is a representative of the Khromyadorius.

Some experts consider the Dorylaimea class by the Enoplea subclass.

Classes include 31 detachments, more than 200 families and about 3,000 genera. Currently, about 30 thousand species are described, but nematode variety involves about a million species.

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Main representatives

Fig. 2. Potato nematodes.

Fig. 3. Ostrida.

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