General characteristics of flatworms. Video lesson "Type flatworms Habitat flat

With a little frown, let's start the description worms. What to do if there are such trump cards in the thick "deck" of the natural diversity of life forms.

I write "trump cards" not only because " worms". The evolution of multicellularity from two-layer has led to much more perfect forms of organisms with a three-layer body structure. And then nature had to tinker for a long time, creating not one, but whole.

Somehow it even becomes a shame for all mammals, which represent only a separate class of organisms in the type of chordates. And here, "some kind of worms" - and whole three types: flatworms, roundworms and annelids.

Well, let's start everything in order, so:

……………… Type Flatworms (three layers)

…………………………………. K l . a. With. With. s

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.. Ciliary worms……………………….. Flukes……………………….. Tapeworms

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White planaria…. Liver fluke …… …………… Bull tapeworm ________________________________________________________________________________________________

……………………………………………….. More than 15 thousand species

Habitat : marine and fresh water bodies, moist soil, human and animal organisms.

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Structure: bilaterally symmetrical . For the first time in embryos, a third germ layer – mesodermfrom which parenchymal cells and the muscular system develop. Body flattened.

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Integuments of the body and muscular system: skin-muscular sac - from a single-layer epithelium (may to be with eyelashes) and three layers smooth muscles (circular, longitudinal and oblique).

Traffic: muscle contraction (flukes, tapeworms) or movement of cilia andmuscles (ciliary worms).

body cavity: missing , the internal organs are located inparenchyma.

Digestive system:has two sections - anterior (mouth, pharynx) and middle (branches intestines). The bowel is closed anal opening is missing and leftover food is removed. through the mouth. At the tapeworms digestive system missing- absorption of food by all cells of the body. As you remember, this is one of the forms of biological progress -.

excretory system: appears for the first time formed by a system of tubules. one end starts in the parenchyma stellate cell with a bunch of cilia, and the other flows into excretory duct. ducts combined into one or two common channels ending excretory pores. Elementary unit of the system areprotonephridia.

Nervous system:from supraesophageal ganglions(ganglia) and longitudinal nerves trunks, related cross jumpers(ladder type).

Sense organs: touch and chemosensitive cells. Free-living people have organsvision and balance.…………..

reproductive system: to usually hermaphrodites.Men'sreproductive system: testes, vas deferens, ejaculatory duct and copulatory organ. Women'sreproductive system: ovary, oviduct, uterus, yolk glands.

1. The appearance of the third germ layer -mesoderm.
2. The appearance of the excretory system - protonephridia.
3. Emergence of the nervous system ladder type.

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Who has questions about the article to biology tutor via skype, comments, wishes - please in the comments .

2. What is the way of life of representatives of various groups of flatworms? how are the features of the structure of worms related to the image life. And habitat?

2) what kind of lifestyle do representatives of various groups of flatworms lead? How are the structural features of worms related to the way of life and habitat?

representatives of different classes? How are the structural features of worms related to their way of life and their habitat? 3. Using the example of the structural features of flat, round and annelids, list the signs of organization complication in comparison with intestinal cavities. 4. What diseases do flatworms cause? What is their prevention? 5. What features of the structure and lifestyle are typical for representatives of the type Roundworms? 6. Why did annelids get such a name? What is characteristic of the structure of each segment? 7. Based on what features do annelids belong to more complex animals than previously studied

12 Ascaris body cavity a) filled with connective tissue b) filled with liquid c) filled with air d) absent
13 In each segment of the body of an earthworm, a) nerve nodes b) excretory tubes c) annular blood vessels d) all answers are correct
14 An earthworm from the sense organs has a) smell b) taste c) hearing d) no special sense organs
15 An earthworm breathes a) in an oxygen-free environment b) atmospheric air c) both options are possible d) there is no breathing
16 The shell of an ordinary pond snail is covered with a layer of a) lime b) a horn-like substance c) chitin d) silicon
17 In the circulatory system of the pond snail there are
a) two-chamber heart and one circle of blood circulation b) two-chamber heart and open circulatory system c) open circulatory system, the function of the heart is performed by two vessels in the front of the body d) one-chamber heart and open circulatory system
18 Gastropods include a) naked slug b) livebearer c) bitinia d) all answers are correct
19 The chitinous cover of arthropods performs the functions of a) protection b) thermoregulation c) gas exchange d) all answers are correct
20 Cancer heart has a) two sections: atrium and ventricle b) three sections: two atria and one ventricle c) one section d) the heart is absent
21 The nervous system in cancer consists of a) supraoesophageal ganglion b) suboesophageal ganglion c) ventral nerve cord d) all answers are correct
22 The abdomen of the cross-spider has a) three segments b) five segments c) non-segmented structure d) none of the answers is correct
23 The process of digestion in a cross-spider:
a) intracavitary b) partially extracavitary c) completely extracavitary d) liquid components are digested outside the digestive system, and solid ones in the stomach of a spider
24 The body of arthropods consists of:
a) head, chest and abdomen b) head and trunk c) cephalothorax and trunk d) head, chest and abdomen; cephalothorax and abdomen.
25 In insects, the number of pairs of motor limbs can be equal to
a) 3 b) 4 c) 5 d) all answers are correct
26 Oxygen to the tissues of insects is supplied by diffusion through
a) the walls of the capillaries b) the walls of the trachea c) the walls of the lung sacs d) enters first into the trachea, then into the capillaries
27 Fish are of the type:
a) chordateless b) semichordate c) chordate
28 The body is covered with bony scales: a) only in cartilaginous fish b) only in bony fish c) in all fish, with rare exceptions
29 Fish eyes are always open because they have:
a) the eyelids have grown together and turned into a transparent shell b) the eyelids are absent c) the eyelids are motionless
30 The spinal cord in fish is located
a) under the spine b) in the spinal canal, which forms the upper arches of the vertebrae c) above the spine
31 The circulatory system in fish
a) closed b) open c) open in cartilage and closed in bone
32 Fish body temperature
a) constant, and does not depend on the temperature of the medium b) variable, but does not depend on the temperature of the medium c) non-constant and depends on the temperature of the medium
33 skin of reptiles
a) has sebaceous glands b) dry (without glands) c) has a small amount of glands that secrete mucus
34 The heart of reptiles
a) three-chamber b) three-chamber, except crocodiles c) four-chamber
35 Fertilization in reptiles
a) external b) internal c) both external and internal
36 Snake is
a) legless lizards b) snakes c) a special group of reptiles
37 In all mammals, the thoracic cavity is separated from the abdominal septum
a) mesentery b) ganglion c) diaphragm d) cuticle
38 The following element does not belong to the skeleton of the lower limb
a) tarsus b) thigh c) lower leg d) radius
39 Animals are characterized by ray symmetry of the body
a) mollusks b) flatworms c) coelenterates d) fish
40 Eliminate the excess
a) scapula b) clavicle c) crow bones d) humerus
41 Bird Science is
a) poultry farming b) ornithology c) cynology d) zoology
42 Keel on the sternum of birds
a) contributes to the dissection of air during flight b) increases the area of ​​attachment of the pectoral muscles c) does not matter as an adaptation to flight
43 What digestive organs arose in birds due to the absence of their jaws and teeth
a) goiter b) glandular part of the stomach c) muscular part of the stomach d) small intestine
44 Mammals spread across the Earth due to the fact that
a) were small in size b) fed their young with milk c) were warm-blooded d) all answers are correct
45 Fabrics first appeared in
a) protozoa b) coelenterates c) flatworms d) annelids
46 Darwin's theory states that all organisms
a) immutable and created by higher powers b) were first created and then evolved naturally c) arose and

"Features of the structure of the planaria" - The internal structure of the white planaria. White planaria or dairy. White planaria. General characteristics of the type. The structure of the white planaria. General signs. The excretory system of a planaria. Eyelash worms. Coelenterates. Variety of flatworms. Planarian body regeneration. White planaria. Various types of planarians. Bilateral and radial symmetry of the body. Body layers of planaria and hydra. The internal structure of a planaria.

"The structure of flatworms" - Movement. Digestive system of flukes. Nervous system. Sense organs. Eyelash worms. Turbellaria. excretory system. Sexual system. Life cycles of tapeworms. The reproductive system of flukes. Flukes are extremely prolific. Flukes class. Gas exchange and transport of substances. Digestive system of ciliaries. Type Flatworms. Tape worms. Development of flukes. The reproductive system is tape.

"The structure of planaria" - Type Flatworms. excretory system. The appearance in the process of development of the third germ layer. Eggs are covered with dense shells. Dairy planaria. Space between organs. Planarian movements. Sexual system. Digestive system. Signs of flatworms. Planarian body. Type Ciliary worms. Flatworms. The internal structure of a planaria. Ring muscles. Single layer epithelium. Nervous system.

"The structure of the white planaria" - Integuments of the body. Platehelminthes. Nephridia and accumulation kidneys. Variety of flatworms. Group members. Flatworms. The structure of the planaria. Structure. Capturing food by white planaria. Location of muscles. Nervous system and sense organs. Musculature. Throat and intestine. Food and movement. Complication of the body cavity. Turbellaria class. Ringed worms. The nervous system of the white planaria.

All worms can be divided into three types (flat, ringed, round), each of which has its own characteristic features. This type refers to invertebrates lacking a body cavity and possessing bilateral symmetry.

The main signs of the type of flatworms

• digestive;
• nervous;
• sexual;
• excretory.

This type has the presence of several systems and even the rudiments of organs

Circulatory system

Not available, but the function of the blood is performed by the parenchyma, consisting of connective cells. It is she who transports nutrients in the body.

Digestive system

Rather simplified, it consists of a pharynx and intestines.

The pharynx is powerful, can:

• suck;
• twist and wrap around your prey.

The intestine consists of two sections - anterior and middle, most often branched. It has a closed structure, so that all undigested waste exits through the mouth. The mouth opening is located closer to the middle of the body of the worm.

Free worms are mostly predators and they even have a kind of adaptation for capturing prey. This system is not observed in all classes; more primitive worms do not have it. For example, tapeworms feed on the entire surface.

excretory system

The excretory system is quite large and consists of many tubules that combine and lead to the excretory pores.

The parenchyma contains special cells that drive harmful substances into the tubules. For humans, these excretory products are very dangerous and toxic along with poison.

Muscular system

Presented, which form muscle fibers covered with epithelium. By contracting these fibers, the worms can move about.

Nervous system

In the upper part of the worm there are two head nodes, two nerve trunks descend from them. Longitudinal nerve trunks penetrate the body of the worm completely and are interconnected by transverse nerves, similar to a short flight of stairs.

With the help of dermal cilia, some worms can:

• feel the temperature
• other external stimuli.

And among free worms there are representatives who have developed organs of vision (pigments that react to light) and balance.

species diversity

There are three classes of this type:

1. Flukes.
2. Tape.
3. Eyelash worms.

Flukes: class representatives and characteristics

Class members:

General characteristics of the class flukes:

Tapeworms: representatives of the class and characteristics

General characteristics of the tapeworm class:

Class members:

• is in stagnant water - ponds, ditches, very active. Covered with cilia, uses them to move on the water surface and attach to the bottom. The length is about 35 cm. The digestive system is developed, it feeds mainly on crustaceans and small invertebrates. Reproduction is sexual and asexual (divided in half, and then each half is completed). Wide range of habitat, found almost everywhere.
• Ehrenberg mesostoma- a flat leaf-shaped body, slightly convex, transparent and colorless, in old worms it is brown. Unlike planarians, the intestines are straight, not branched. They live attached to aquatic plants. The mesostoma is predatory, preying on crustaceans, worms, insects and even freshwater hydras. It is able to tolerate the drying up of reservoirs, live in flooded meadows, puddles, and after their drying out, the eggs of the mesostom remain capable of development.
• Ground worm rhynchodemus- soil worm, lives in damp places, most often under stones. Habitat Europe and North America. It can reach 12 mm, the color is brown with red longitudinal spots. Cilia are preserved on the ventral side of the body, moves by muscle contraction. Predator that eats insects.

General characteristics of ciliary worms:

Number of species: about 25 thousand.

Habitat: They live everywhere in humid environments, including the tissues and organs of other animals.

Structure: Flatworms are the first multicellular animals in which, in the course of evolution, bilateral symmetry, three-layer structure, real organs and tissues appeared.

Bilateral(bilateral) symmetry - this means that an imaginary axis of symmetry can be drawn through the animal's body, while the right side of the body will be a mirror image of the left.

During embryonic development, three-layer animals are laid three layers of cells: outer - ectoderm, average - mesoderm, internal - endoderm. Certain organs and tissues develop from each layer:

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

from the mesoderm - muscle and connective tissues, reproductive, excretory systems;

from the endoderm - the digestive system.

In flatworms, the body is flattened in the dorsal-abdominal direction, there is no body cavity, the space between the internal organs is filled with mesoderm cells (parenchyma).

Digestive system includes the mouth, pharynx and blindly closed intestine. The absorption of food and the excretion of undigested residues occurs through the mouth. In tapeworms, the digestive system is completely absent; they absorb nutrients from the entire surface of the body, being in the intestines of the host.

excretory organs - protonephridia. They consist of thin branching tubules, at one end of which are fiery (flickering) cells star-shaped, immersed in the parenchyma. A bundle of cilia (flickering flame) departs inside these cells, the movement of which resembles the flickering of a flame (hence the name of the cells). Flame cells capture liquid decay products from the parenchyma, and cilia drive them into the tubule. The tubules open on the surface of the body with an excretory pore through which decay products are removed from the body.

Nervous system ladder type ( orthogon). It is formed by a large head paired ganglion (ganglion) and six nerve trunks extending from it: two on the ventral side, two on the dorsal and two on the sides. Nerve trunks are interconnected by jumpers. From the ganglion and trunks, nerves depart to the organs and skin.

Reproduction and development:

Flatworms are hermaphrodites. Sex cells mature in the sex glands (gonads). Hermaphrodite has both male glands - testes, and female - ovaries. Fertilization is internal, usually cross, i.e. worms exchange seminal fluid.

CLASS CILIATION WORMS

Dairy planaria, a small aquatic animal, the adult has a length of ~25 mm and a width of ~6 mm, the body is flat, milky white. At the front end of the body are two eyes that distinguish light from darkness, as well as a pair of tentacles (chemical sense organs) necessary for finding food. Planarians move, on the one hand, thanks to the work of the cilia covering their skin, on the other hand, due to the contraction of the muscles of the skin-muscular sac. The space between the muscles and internal organs is filled with parenchyma, in which intermediate cells responsible for regeneration and asexual reproduction.

Planarians are carnivores that feed on small animals. The mouth is located on the ventral side, closer to the middle of the body, from it comes a muscular pharynx, from which three branches of a closed intestine depart. Having captured the victim, the planaria sucks out its contents with its throat. Digestion occurs in the intestine under the action of enzymes (intestinal), intestinal cells are able to capture and digest pieces of food (intracellular digestion). Undigested food remains are removed through the mouth.

Reproduction and development. Ciliary - hermaphrodites. Cross fertilization. Fertilized eggs fall into a cocoon, which the worm lays on underwater objects. The development is direct.

CLASS FLUES

4 - sporocyst; 5 - redia; 6 - cercariae; 7 - adolescarium.

CLASS TAPE WORMS

Bull tapeworm- a tapeworm, reaches a length of 4 to 12 meters. The body includes a head with suckers, a neck and a strobile - a tape of segments. The youngest segments are at the neck, the oldest are sacs filled with eggs, located at the posterior end, where they come off one by one.

Reproduction and development. Bull tapeworm is a hermaphrodite: in each of its segments there is one ovary and many testes. Both cross-fertilization and self-fertilization are observed. The posterior segments, filled with mature eggs, open and, with feces, are brought out. Cattle (intermediate host) can swallow eggs along with grass, in the stomach microscopic larvae with six hooks come out of the eggs, which enter the bloodstream through the intestinal wall and spread throughout the body of the animal and enter the muscles. Here the six-hooked larva grows and turns into Finn- a vial, inside of which there is a tapeworm head with a neck. A person can become infected with fincas by eating undercooked or undercooked meat from an infected animal. In the human stomach, a head emerges from the finca, which is attached to the intestinal wall. New segments bud from the neck - the worm grows. Bull tapeworm emits toxic substances that cause intestinal disorders and anemia in humans.

Development pork tapeworm has a similar character, its intermediate owner, in addition to a pig and a wild boar, can also be a person, then Finns develop in its muscles. Development wide ribbon is accompanied by a change of two intermediate hosts: the first is a crustacean (cyclops), the second is a fish that has eaten a crustacean. The definitive host may be a human or a predator that has eaten the infected fish.

New concepts and terms: mesoderm, skin-muscular sac, tegument, hypodermis, reduction, protonephridia (flame cells), orthogon, strobilus, ganglion, gonads, hermaphrodite, direct and indirect development, definitive and intermediate host, miracidium, cercaria, finna, segment, armed and unarmed tapeworm.

Questions for reinforcement.

1. Who is called the intermediate host? final?

6. Why is it dangerous to drink raw water, swim in ponds near livestock grazing? Why is it important to wash your hands with soap after interacting with animals?

7. For which worms is oxygen harmful?

8. What aromorphoses led to the appearance of the type Flatworms?

Lectures on zoology

Type Roundworms

Answer plan:

General characteristics of roundworms

The structure of the body of Ascaris human

Reproduction and development of Ascaris human

Classification of roundworms, variety of species

The value of roundworms in nature and human life