Type Flatworms. Classes: Eyelash, Flukes, Band

Answers to school textbooks

Structural features of flatworms:

The body is elongated and flattened in the dorsal direction, the anterior and posterior ends are clearly distinguished;

They are bilaterally symmetrical, which allows more active movements than in radially symmetrical animals (coelenterates);

There are four types of tissues: integumentary, connective, nervous and muscular;

The body wall is a skin-muscular sac formed by a single-layer ectodermal epithelium and muscles lying in three layers (outer - circular muscles, the next, deeper - longitudinal, deepest layer - diagonal muscles);

Inside the skin-muscle sac there is a loose tissue - the parenchyma, in which all the internal organs are located;

The digestive system is blind and has no anus;

The nervous system consists of two nerve nodes in the anterior part of the body and longitudinal strands extending from them, connected by jumpers;

The excretory system is represented by branched tubules that begin in the parenchyma with stellate cells that have a cavity with a bundle of cilia in it; vibrations of the cilia cause a flow of fluid containing metabolic products, directing it into the tubules, which communicate with the external environment through the excretory openings;

The reproductive system is hermaphrodite, consists of the sex glands and a complex system of ducts that serve to excrete germ cells;

2. What sense organs do flatworms have?

The sense organs, as a rule, are represented by separate skin cilia - processes of sensitive nerve cells. Some free-living representatives of the type, in the process of adapting to the conditions of existence, acquired primitive organs of vision - light-sensitive pigmented eyes and organs of balance.

3. What is parenchyma?

Parenchyma is a loose connective tissue that fills the gaps between organs. Parenchyma functions:

1) support;

2) storage of nutrients;

3) participation in metabolism and digestion.

In the absence of food, the parenchyma is depleted.

4. How it works nervous system flatworms?

The nervous system is represented by two nerve nodes located at the front end of the body - the brain ganglia and the nerve trunks extending from them, connected by jumpers, i.e., in flatworms, the ladder-type nervous system.

5. What are the structural features of the excretory system of flatworms?

6. How is the excretory system of flatworms arranged?

In the parenchyma lie stellate cells that secrete water and metabolic products into the lumen of the tubules. The stellate cells have a bundle of cilia in the recess, which continuously vibrates and drives the fluid outward through special tubules. The tubules combine into tubules and form pores on the surface of the body. These excretory organs also regulate osmotic pressure owing to which flatworms are common in fresh waters.

7. What is the lifestyle of ciliary worms?

The ciliary worms include free-living marine or freshwater worms (dairy planaria, black planaria, many-eyed), as well as terrestrial ones. As a rule, ciliary worms are predators. They eat many protozoans (ciliates, rhizopods, flagellates), nematodes, small crustaceans, mosquito larvae - often larger animals than themselves.

8. What structural features of flukes are associated with their lifestyle?

Dense protective shell covering the body;

Two suction cups for attaching to host tissues;

Hermaphroditism; high fertility;

Simplified sense organs.

9. Describe the development of the fluke.

An adult (sexually mature) individual of the liver fluke lives in the liver of large herbivorous mammals and humans, feeds mainly on bile, as well as blood and liver cells, sometimes causing the death of the main host.

10. Who is called the intermediate host? What is the intermediate host for the liver fluke?

11. What are the structural features of tapeworms?

Features of the structure of tapeworms:

Ribbon body, consisting of a head, neck and several thousand segments, which increase in size towards the end of the body;

On the head there are organs of attachment to the intestinal walls of the host (suckers, suction slots, hooks);

In each segment - hermaphroditic reproductive system;

The last segments are filled with fertilized eggs, these segments come off and are brought out;

The digestive system is absent, food is absorbed by the entire surface of the body;

The nervous system is formed by the head node, from which nerve trunks run along the body.

12. What is a Finn?

Finn is one of the stages in the development of a tapeworm. It is a vial filled with liquid, in the cavity of which there is a formed worm head with four suckers.

Finna enters the intestines of a person with undercooked or undercooked meat, the Finna attaches to the intestinal wall, and the growth of a worm begins, poisoning a person with metabolic products that cause indigestion and anemia.

13. How does the development of the bull tapeworm occur?

People sometimes carelessly treat helminthic invasion as an unpleasant, but quite easily tolerated ailment. Accordingly, their beliefs do not call for extreme caution when coming into contact with any kind of dirt, poorly processed food, or contact with pets.

Such criminal negligence has its sad results. Worms are capable of killing their prey, apart from pain and organ damage. The most dangerous are helminths that feed on blood and beneficial substances inside a person.

Malarial plasmodium destroys blood cells and can bring the victim to death.

Consequences of infection:

development of malignant tumors;
immunity weakens;
metabolism is disrupted.

Manifestations of helminthic invasion are very different from each other. But they also have common symptoms:

muscle pain that weakens and swells;
joints hurt, although they were not injured;
the liver and spleen increase in size;
skin rash;
heat.

To them you can add:

Worms sometimes bring the body of an infected person into such a state that a full healthy life, even after their removal, is no longer possible. Therefore, if you find any of the symptoms, you should immediately consult a doctor.

Photo of worms that can live in you

Symptoms of their presence are not immediately and not all pronounced. A long stay of worms will bring the body to chronic diseases. It is believed that many diseases begin with worms. Before you start treatment, you should first know your inner enemy, so as not to fight blindly.

Worms that settle in a person are divided into types:

roundworms;
tapeworms;
flukes.

Below are photos of worms in the human body:

Thanks to such materials, smart people are more armed to protect themselves and their loved ones. But no one should do anything himself in the destruction of uninvited "guests".

Useful video

Below we offer to watch a documentary on the symptoms and infection with worms:

The vast majority of helminths have a negative effect on the general well-being and health of a person, provoking the development of very serious diseases. Keeping this in mind, when the first signs of malaise appear, which do not go away with the treatment of a cold or skin rash with headaches, you should consult a doctor for an appointment for diagnosis.

How to prevent worm infestation? Is it necessary to constantly limit yourself in one or another vacation, literally “squeezing” your life in a vise by observing complex postulates?

But everyone needs to start with themselves, because all modern achievements mean nothing if you simply neglect personal hygiene and preventive measures for those family members who live in our house. Being attentive to your health, detecting in time (if an infection has occurred), competently and promptly proceeding to treatment - all this will help prevent a big personal disaster and the spread of the disease in your environment.

Question 1. List the differences between flatworms and intestinal animals.

First, unlike coelenterates, which have radial symmetry, flatworms have bilateral symmetry.

Secondly, coelenterates are two-layer animals that do not have internal organs. The body of flatworms is made up of many layers of cells. Inside the musculocutaneous sac there are internal organs united into organ systems: digestive, excretory, nervous and sexual. The space between these organs is filled with cells, so there is no internal cavity.

Question 2. What features of the structure and lifestyle make it possible to divide the type of flatworms into classes?

Flukes class. The body shape of flukes is most often leaf-shaped. Worms of this class lead an exclusively parasitic way of life. In this regard, they have special organs of attachment to the body of the host - suckers. Flukes are characterized by development with alternation of generations.

Question 3. Why do tapeworms lack digestive organs?

7. Type flatworms. Classes: Eyelash, Flukes, Band

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Question 1. List the differences between flatworms and intestinal animals.

First, unlike coelenterates, which have radial symmetry, flatworms have bilateral symmetry.

Question 2. What features of the structure and lifestyle make it possible to divide the type of flatworms into classes?

Question 3. Why do tapeworms lack digestive organs?

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hallmark flatworms- flattened body in the dorsal-abdominal direction. Unlike coelenterates, in flatworms between ectoderm and endoderm(outer and inner layer of cells) is the third layer of cells - mesoderm. Therefore, they are called three-layer animals that do not have a body cavity (it is filled parenchyma- a loose cell mass in which internal organs are placed).

The symmetry of the body is bilateral. There are over 12,000 species in the type. The type of flatworms is divided into classes: ciliary, flukes, tape worms.

Class ciliary worms

Eyelash worms live in the seas, fresh waters and wet soil. They feed mainly on small animals. Their body is covered with cilia, with which they move. One of the representatives is white planaria.

At the front end of the body, two lateral outgrowths (organs of touch) are visible. Next to them are two eyes, with the help of which the planarian distinguishes light. Planaria is a predator. Her pharynx is a trapping apparatus that protrudes out through the mouth, located on the ventral side, penetrates into the prey and sucks out its contents. Digestion of food takes place in the branched intestine. Undigested residues are thrown out through the mouth. The planarian breathes with the entire surface of the body. The excretory organs consist of a system of branched tubules located on the sides of the body. Liquid harmful metabolic products are excreted through the excretory pores.

Nerve cells are assembled into two nerve trunks, which are connected by thin bridges. At the anterior end of the body, they form a thickening - ganglion, from which to the sense organs (eyes and organs of touch) and to the rear end of the body depart nerve processes.

Reproductive organs - two oval ovaries and numerous testes, develop in the body of one individual and form germ cells - eggs and spermatozoa. Animals in which there are both female and male organs reproduction are called hermaphrodites. Their fertilization is internal, cross, after which the planaria lays cocoons with eggs. Her development is direct.

fluke class

Once in the water, microscopic larvae equipped with cilia develop from the eggs. They are introduced into the body of the mollusc of a small pond snail, in which they grow, multiply, and tail larvae appear. These larvae leave the mollusk, actively swim in the water, then attach themselves to plants, discard their tail, become covered with a thick shell - a cyst is formed. With grass or water, the cyst enters the intestines of the cow, where an adult worm develops from it. A person can become infected with a liver fluke if he drinks water from a dirty reservoir.

class of tapeworms

Tapeworms - almost all hermaphrodites, are characterized by high fecundity and development with a change of hosts. Each segment of the bull tapeworm has one ovary and many testes. The eggs mature in the oldest, posterior segments, which break off and come out with feces. Further development of the eggs will occur if, together with the grass, they are swallowed by a large cattle. In the stomach of a cow, larvae emerge from the egg, which, by perforating the walls of the intestine, enter the bloodstream.