Integuments of the body Outside, the body is covered with a single-layer epithelium. In ciliary worms, or turbellaria, the epithelium consists of cells that carry cilia. Flukes, monogeneans, cestodes, and tapeworms lack ciliated epithelium for most of their lives (although ciliated cells may occur in larval forms); their covers are represented by the so-called tegument, in a number of groups bearing microvilli or chitinous hooks. Tegumented flatworms belong to the Neodermata group. Flatworms can regenerate 6/7 of their body.
Musculature Under the epithelium there is a muscular sac, consisting of several layers of muscle cells that are not differentiated into individual muscles (a certain differentiation is observed only in the region of the pharynx and genital organs). The cells of the outer muscle layer are oriented across, the inner - along the anterior-posterior axis of the body. The outer layer is called the layer of circular muscles, and the inner layer is called the layer of longitudinal muscles.
Nervous system and sensory organs The nervous system is represented by nerve nodes located in the anterior part of the body of the worm, cerebral ganglia and nerve columns extending from them, connected by jumpers. 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 living conditions, acquired light-sensitive pigmented eyes - primitive organs of vision and organs of balance.
Structure The body is bilaterally symmetrical, with clearly defined head and tail ends, somewhat flattened in the dorsoventral direction, in large representatives it is strongly flattened. The body cavity is not developed (with the exception of some phases of the life cycle of tapeworms and flukes). The exchange of gases is carried out through the entire surface of the body; respiratory organs and blood vessels are absent.
Questions: How many flatworms live in Russia? What are the body coverings of flatworms? What kind of muscles? What are the sense organs? Briefly describe the structure of the body. How do flat people eat? How do they breathe? How do they reproduce?
Interesting Facts 1. By digestion, flatworms are able to "learn". A group of scientists have made an unusual discovery regarding the abilities of flatworms. It turns out that if planar worms are first taught to go through the maze, then grind them into a puree and let other worms eat it, then such worms will be able to go through this maze the first time.
Interesting facts 2. Different-sex species of worms - schistosomes are inseparable throughout life. The female lives in the pocket of the male all her life.
Interesting facts 3. Almost all types of flatworms can turn inside out. 4. And here are some more interesting facts about flatworms. For example, flatworms are truly almost immortal. If you cut off a very small piece from the worm, approximately 1/100 of the whole worm, then it is still able to recover to the whole organism.
Interesting facts 5. On the skin of some planarians living in fresh water, scientists have found nettle cells, which are very similar to stinging cells found in coelenterates. It turns out that these cells really belonged to the coelenterates, which subsequently ate the ciliary worms. Stinging cells are not digested by worms. They get into their skin and serve to perform a protective function and attack.
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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?
1) Name the main groups included in the type Flatworms, and their characteristic distinguishing features using the example of representatives of each group.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?
.Name the main classes of the type Flatworms and their characteristic distinguishing features using the example of representatives of each class. 2. What lifestyle do they leadrepresentatives 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 complication of organization 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
11 Flatworms a) have bilateral symmetry b) a skin-muscular sac c) a special excretory system d) all answers are correct12 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) no heart
21 The nervous system in cancer consists of a) the supraesophageal ganglion b) the subpharyngeal ganglion c) the 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
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. In the intestine, digestion occurs 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 blood 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, musculocutaneous sac, tegument, hypodermis, reduction, protonephridia (flame cells), orthogon, strobili, 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
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:
- Flukes.
- Tape.
- 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:
a brief description of
|
Habitat and appearance |
Size 10-15 mm, leaf-shaped, live in ponds and slow-flowing reservoirs |
|
body cover and musculocutaneous sac |
The body is covered with a single layer (ciliary) epithelium. The superficial muscle layer is annular, the inner one is longitudinal and diagonal. There are dorso-abdominal muscles |
|
body cavity |
The body cavity is absent. Inside is spongy tissue - parenchyma |
|
Digestive system |
Consists of the anterior (pharynx) and the middle, which has the appearance of highly branched trunks ending blindly |
|
excretorysystem |
Protonephridia |
|
Nervous system |
The brain ganglion and the nerve trunks coming from it |
|
sense organs |
Tactile cells. One or more pairs of eyes. Some species have balance organs |
|
Respiratory system |
No. Oxygen is supplied through the entire surface of the body |
|
reproduction |
Hermaphrodites. Fertilization is internal, but cross-fertilization - two individuals are needed |
Typical representatives of ciliary worms are planaria(Fig. 1).
Rice. one.Morphology of flatworms on the example of dairy planaria. A - the appearance of the planaria; B, C - internal organs (diagrams); D - part of the transverse section through the body of the dairy planaria; D - terminal cell of the protonephridial excretory system: 1 - oral opening; 2 - throat; 3 - intestines; 4 - protonephridia; 5 - left lateral nerve trunk; 6 - head ganglion; 7 - peephole; 8 - ciliary epithelium; 9 - circular muscles; 10 - oblique muscles; 11 - longitudinal muscles; 12 - dorsoventral muscles; 13 - parenchyma cells; 14 - cells forming rhabdites; 15 - rabdits; 16 - unicellular gland; 17 - a bunch of cilia (flickering flame); 18 - cell nucleus
general characteristics
Appearance and covers . The body of ciliary worms is elongated, foliate. Sizes vary from a few millimeters to several centimeters. The body is colorless or white. Most often, ciliary worms are painted in various colors with grains. pigment embedded in the skin.
body covered single layer ciliated epithelium. The covers have skin glands scattered throughout the body or collected in complexes. Of interest is the variety of skin glands - rhabdit cells, which contain light-refracting rods rabdites. They lie perpendicular to the surface of the body. When the animal is irritated, the rhabdites are thrown out and swell greatly. As a result, mucus is formed on the surface of the worm, possibly playing a protective role.
Skin-muscular sac . Under the epithelium is basement membrane, which serves to give the body a certain shape and to attach muscles. The combination of muscles and epithelium forms a single complex - skin-muscle sac. The muscular system is made up of several layers smooth muscle fibers. The most superficial circular muscles, somewhat deeper longitudinal and the deepest diagonal muscle fibers. In addition to the listed types of muscle fibers, ciliary worms are characterized by dorso-abdominal, or dorsoventral, muscles. These are bundles of fibers running from the dorsal side of the body to the ventral side.
Movement is carried out due to the beating of cilia (in small forms) or contraction of the skin-muscular sac (in large representatives).
clearly defined body cavity ciliary worms do not. All gaps between organs are filled parenchyma- loose connective tissue. The small spaces between the parenchyma cells are filled with an aqueous liquid, which allows the transfer of products from the intestine to the internal organs and the transfer of metabolic products to the excretory system. In addition, the parenchyma can be considered as a supporting tissue.
Digestive system ciliary worms blindly closed. Mouth also serves for swallowing food, and for throwing out undigested food. The mouth is usually located on the ventral side of the body and leads to throat. In some large ciliary worms, such as freshwater planaria, the mouth opening opens into pharyngeal pocket, in which is muscular throat, able to stretch and protrude out through the mouth. midgut in small forms of ciliary worms is channels branching in all directions, and in large forms, the intestines are represented three branches: one front, going to the front end of the body, and two rear running along the sides to the posterior end of the body.
Main Feature nervous system ciliary worms compared to coelenterates is concentration of nerve elements at the anterior end of the body with the formation of a double node - the brain ganglion, which becomes the coordinating center of the whole body. depart from the ganglion longitudinal nerve trunks connected by transverse ring jumpers.
sense organs ciliary worms are relatively well developed. organ of touch whole skin serves. In some species, the function of touch is performed by small paired tentacles at the anterior end of the body. Sense organs of balance represented by closed sacs - statocysts, with hearing stones inside. organs of vision are almost always available. The eye may be one pair or more.
excretory system for the first time appears as separate system. It is represented two or multiple channels, each of which one end opens outwards, a the other is strongly branched, forming a network of channels of various diameters. The thinnest tubules or capillaries at their ends are closed by special cells - stellate(see fig. 1, D). From these cells in the lumen of the tubules depart bunches of cilia. Due to their constant work, there is no stagnation of fluid in the body of the worm, it enters the tubules and is subsequently excreted. The excretory system in the form of branched canals, closed at the ends by stellate cells, is called protonephridia.
reproductive system quite varied in structure. It can be noted that in comparison with coelenterates in ciliary worms special excretory ducts appear for
expelling germ cells. Eyelash worms hermaphrodites. Fertilization - internal.
Reproduction. In most cases in a sexual way. For most worms direct development, but in some marine species development occurs with metamorphosis. However, some ciliary worms can reproduce and asexually through transverse fission. At the same time, in each half of the body, regeneration missing organs.
