Which organs of flat worms are called a fiscal flame. Nervous system and general characteristics of flat worms

The nervous system of the lattice type, reminds the grille. It consists of a paired brain ganglia and the nerve trunks connected by ring jumpers from it. Typically, two longitudinal trunks are achieved. Feeling authorities are most well developed at free-lived, turbellaria. Some have equilibrium authorities - Stavtocists, almost always have eyes. There are receptors for the perception of mechanical and chemical irritation.

Nervous system flat worms It consists of a pair brain ganglium and the near-theft of nervous trunks connected by ring jumpers from it. This is a primitive brain that performs the role of a regulating nervous center. Flat worms are formed by the central regulatory apparatus of the nervous system. There is an increase in the size and strengthening of the role of Mozgia Ganglia, which from a small nodule, innervating stampsite (equilibrium organ), gradually turns into the main coordinating center of the entire body. At the same time, the nervous system is immersed in the thickness of the parenchyma (loose connective tissue), providing the protection of ganglia and stems from possible damaging effects of the external environment.

Another important moment In the evolution of the nervous system of flat worms - the number of longitudinal trunks isolated from disorderly nervous plexus, premitive forms are quite significant (5-6 pairs). During the evolution, it decreases to 2 or even 1 pair. All longitudinal trunks are connected by transverse ring jumpers, so that the nervous system acquires the type of proper grille. Such a nervous system with the help of primitive senses can perceive the simplest effects (changes in illumination, surface fluctuations in which the animal crawls ...) and respond to them accordingly, "giving commands" to other organs and tissues. In more highly organized worms (ring worms, and to which the rainworm belongs) the evolution towards the decrease in the nerve trunks led to the formation of the abdominal nervous chain.

The disadvantage of the staircase type of the nervous system is to reduce regeneration - the restoration of the lost part of the body is possible only when maintaining the integrity of the head end. The advantage is that, in contrast to the shepherd, the nervous system forms a head ganglia, which coordinates the work of the whole organism, regulates the attitudes of the body with an external environment. Scientists managed to develop primitive conditional reflexes at the White Planaria, which indicates that these animals can adapt to one or another environmental conditions during their lives.

Turbellaria. Photo: Christopher Laumer

Nervous class system crymfish It consists of a cluster of the nerve cells of the head ganglion (node) and the nervous trunks departing from it. Its main feature is the concentration of nerve elements at the head end. Between adjacent nervous trunks there is a system of thin jumpers. This is the staircase type of the structure of the nervous system. V The senses are presented by primitive eyes, equilibrium authorities - stampets (closed bags with pebbles from carbon dioxide inside). The skin has tactile cells.

The nervous class of the class of the seashests consists of a regulatory nerve ring and from it three pairs of nerve trunks, interconnected by jumpers.

The nervous system of class belt worms consists of a nervous gangline located in the head, and two side trunks passing along the body.

Flat worms general characteristics

Characteristic types of type are as follows:

The body is flat, its shape is leasting (at the cereal and loser) or a belt-shaped (in tape worms).

For the first time in the animal world, representatives of this type developed bilateral (bilateral - approx. E. Through the body, only one longitudinal plane of symmetry can be carried out, dividing it into two mirror-like parts.

In addition to Ektoderma and Entoderm, they have a medium germinal sheet - Mesoderm. Therefore, they are considered the first three-layer animals. The presence of three germinal leaflets gives the basis for the development of various organ systems.

The body wall forms a knee-muscular bag -Sullness of the outdoor single-layer epithelium and several layers of muscles - ring, longitudinal, oblique and spinal abdominal. Therefore, the body of flat worms can make complex and varied movements.

The body cavity is absent, since the space between the body wall and the internal organs filled with a loose mass of cells - parenchyma. It performs a reference function and serves as a depot of spare nutrients.

Flatworm. Photo: Chris.

The digestive system consists of two departments: the ectodermal front intestine, represented by mouth and a muscular throat capable of predatory cilia worms to turn outward, penetrate the victims and suck its contents, and blindly closed an entodermal middle intestine. Many species from the main sections of the middle intestine, there are many blind branches penetrating into all parts of the body and delivering dissolved nutrients. Imaginary residues are thrown through the mouth.

Outline system protonphridial type. Excess water and final products of metabolism (mainly urea) are derived through excretory pores.

The nervous system is more concentrated and is represented by pair head gangle and extending from it longitudinal nerve trunks connected by ring jumpers. Nervous trunks are formed located along its entire length of the bodies of nerve cells and their processes. This type of organization of the nervous system is called stem. All flat worms are developed by tanging, chemical feeling, equilibrium, and free-lived - and vision.



Number of species: About 25 thousand.

Habitat: Inhabit everywhere in wet environments, including fabrics and other animal organs.

Structure: Flat worms are the first multicellular animals, in which bilateral symmetry, three-layerness, real organs and tissues appeared during evolution.

Bilateral (bilateral) symmetry - this means that through the body of the animal you can spend an imaginary axis of symmetry, while the right side of the body will be mirrored to the left.

During the embryonic development of three-layer Animals are laid three layers of cells: outdoor - etoderma, middle - mesoderma, internal - entoderma. Each layer develops certain organs and fabrics:

skin (epithelium) and nervous system are generated from the ectoderm;

mesoderma - muscle and connective tissue, sexual, excretory system;

from Entoderma - digestive system.

In flat worms, the body is flattened in the spin-abdominal direction, the body cavity is absent, the space between the internal organs is filled with mesoderm cells (parenchyma).

Digestive system Includes mouth, throat and blind intestinal. Absorption of food and excretion of undue residues occurs through the mouth. In the ribbon worms, the digestive system is completely absent, the nutrients are absorbed by the entire surface of the body, being in the intestine of the owner.

Selective organs - protonefridia. They consist of thin branching tubules, at one end of which are located flame (flicker) cellsstar shape immersed in a parenchyma. Inside of these cells, a bug of cilia (flickering flame) is departed, the movement of which resembles the flicker of the flame (hence the name of the cell). Flame cells are captured from parenchyma liquid decay products, and the cilia drive them into the canal. The tubules open on the surface of the body separating sometimes, through which decomposition products are removed from the body.

Nervous systemstaircase ( orthogon). It is formed by a large head paired nervous knot (ganglia) and six nervous barrels from him: two on the abdominal side, two on the dorsal and two sides. Nervous trunks are interconnected by jumpers. The nerves to organs and the skin depart from Ganglia and trunks.

Reproduction and development:

Flat worms - hermaphrodites. Sex cells ripen in germ glanes (gonads). Hermaphrodis has both men's glands - the seeds and women's - ovaries. Fertilization - internal, usually cross, i.e. Worms exchange seed fluid.

Class Classified Cherry

Dairy plane, a small water animal, an adult individual has a length of ~ 25 mm and a width of ~ 6 mm, the body is flat, milk-white. At the front end of the body there are two eyes, distinguishing light from darkness, as well as a pair of tental (chemical feeling) necessary to search for food. Planaria move, on the one hand, thanks to the work of cilia covering their skin, on the other hand, thanks to the reduction of the muscles of the skin-muscular bag. The space between the muscles and the internal organs is filled with Parenkhima, in which they meet intermediate cellsresponsible for regeneration and useless reproduction.

Planaria - predators feed on small animals. The mouth is located on the abdominal side, closer to the middle of the body, there is a muscular throat from it, from which three branches of the closed intestine are departed. Capturing the sacrifice, the planaries sucks its contents. In the intestine, digestion under the action of enzymes (intestinal), intestinal cells are able to capture and digest pieces of food (intracellular digestion). Unpained food remnants are removed through the mouth.

Reproduction and development. Rishichny - hermaphrodites. Fertilization cross. Fertilized eggs fall into the cocoon, which worm postpones on underwater items. Development direct.

Class of chowers

4 - sporocyst; 5 - red; 6 - churches; 7 - Adolescarius.

Class of tape worms

Bull chain - Ribbon worm, reaches a length from 4 to 12 meters. The body includes a head with suction cups, neck and gate - sealer tape. The youngest segments are at the neck, the oldest are the bags filled with eggs, are at the rear end, where they come off one by one.

Reproduction and development. Bull Chain - Hermaphrodge: There is one ovary in every segment and many seeds. It is observed both cross fertilization and self-exploitation. The rear segments filled with ripe eggs are opened, and, with the feces, are outward. Cattle (intermediate owner) can swallow eggs along with grass, microscopic larvae with six hooks come from eggs, which through the intestine wall fall into the blood and spread throughout the body of the animal and are recorded in the muscles. Here, the six-sided larva grows and turns into finn - A bubble, inside of which is a chain chain head. A person can become infected with docks, aief is not sufficiently roasted or woven meat of an infected animal. In the stomach of a man from the fins, the head comes out, which is attached to the intestinal wall. From the neck, new segments are buded - the worm grows. The bullish chain allocates poisonous substances that cause intestinal disorders and anemia in humans.

Development pork chain It has a similar character, his intermediate owner besides a pig and boar, there may be a person, then in his muscles are developing. Development wide Lenteza accompanied by a change of two intermediate owners: the first - the wrapping (cyclops), the second is a fish, eating the lap. The final owner can be a person or a predator, eating infected fish.

New concepts and terms: Mesoderma, skin-muscular bag, tugement, hypoderma, reduction, protonphridey (fiery cells), orthogon, gates, gangliy, gonads, hermaphrodis, direct and indirect development, final and intermediate owner, Miracidium, churches, Finn, segment, armed and unarmed tapeworm.

Questions for consolidation.

1. Who are called an intermediate owner? Final?

6. What is dangerous to drink raw water, swim in water bodies near the grazing of livestock? Why after communicating with animals you need to wash your hands with soap?

7. For what worms oxygen is destroyed?

8. What aromorphoses led to the appearance of the type of flat worms?

Lectures on zoology

Type round worms

Answer:

· General characteristics Round worms

· The structure of the body of the Asskarid of Human

· Reproduction and development of human ascaris

· Classification of round worms, varieties of species

· The value of round worms in the nature and life of a person

Free-lived representatives of the type of flat worms live around the world in the waters of the seas, freshwater reservoirs, wet soil layers, moss. Mostly this is a wilderness. Most often predators. Food serve the simplest microorganisms, insects. This class includes planaries.

The infection of vertebrates and invertebrate animals are exposed. Mammals (including man) and fish, which are the main or intermediate hosts for helminths are mainly invasion.

Meaning in evolution

The value of flat worms in the development of life on the planet is very significant. In the process of evolution, they were the first in many ways:

• Body symmetry. Of the multicellular animals, they were the first to whom the body was symmetrically relative to the same plane. Such symmetry is called bilateral.
• Three-layerness. This means that the body consists of three types of tissues. They develop from 3 petals of the embryo, and not two, as in living organisms before.
• These bodies. Each of the three types of fabrics forms organs performing different functions.

Which signs are distinguished by representatives of this type of living beings? Distinctive features shown in the scheme:

• flattened body, which gave all the type such name;
• the head and tail are clearly pronounced;
• the body is symmetrical. The right and left side are similar;
• there are no cavities inside the body, the organs are in the layer of loose mesoderm (parenchyma);
• the body is concluded in the skin-muscular bag.

The torso is covered with a shell from the layer of coat cells, under which there are three layers of muscle tissue: ring, longitudinal and diagonal. These layers are called a skin-muscular bag.

The central nervous system is a pair of nodes (ganglions) in the head and pair trunks passing through the body and interpretable multiple jumpers. The numerous endings of the peripheral nervous system differ from the trunks and gangliy. They associate CNS with all the organs of Helmint.

To remove life products from the body, special organs - protonphridey serve. Substances are displayed in the intercellular space - parenchyma, from where they are pushed through special cells using cilia movements. Such cells form one or two channels. They remove the disintegration products with liquid through the separation number on the surface of the body.

In some species, poisonous substances accumulate in special cells - atrocytes that are peculiar cumulative kidneys.

In the bulk, flat worms - hermaphrodites. Fertilization occurs inside the body of one helminth. Only some of the seashests have division into men's and women's individuals. The structure and location of the reproductive organs is diverse and is one of the classification factors. Common in the structure of the reproductive system in all flat worms, is the presence of seeds, ovaries, as well as a complex system of tubules serving the processes of fertilization and formation of eggs.

Life cycle

Half-cooled flat worms from the class of seashers live in vertebrate organisms, and the eggs released with excrement to develop further, a water medium is required. When the finished larva comes out, it is independently looking for an intermediate owner (a certain kind of mollusk). Penetrating into his body, goes into the stage of the mother's spirals, which itself is capable of reproduction. As a result, many larvae of another level appear, capable of finding the next intermediate - herbivores, fish, snails - or final owner - man.