Animals that are representatives of bivalves. Type Molluscs. Class Gastropods. Class Bivalves. Class Cephalopods. Topic: “Class Bivalves”

To the class bivalves include bilaterally symmetrical invertebrate aquatic animals such as mollusks. Fossil remains of these mollusks are found in the layers of the early Paleozoic period. In the course of evolution, animals of this class reached their peak in Cretaceous period. Many families gradually became completely extinct, and about 10 modern families of this class still live in water bodies, that is, they have existed for about 400 million years. Currently, about 130 families of this class are known, uniting about 10 thousand modern species. Representatives of bivalve mollusks are oysters, mussels, toothless mussels, pearl mussels, tridacnas, scallops, etc. Bivalve mollusks are widely distributed in the waters of the World Ocean and in fresh water bodies. They are benthic organisms that feed on plankton or plant detritus through filtration. This method of feeding does not require special mobility, therefore the structure of these animals is relatively simplified compared to representatives of other classes such as mollusks. Bivalves lead a sedentary lifestyle, burrowing into the ground, simply sitting on the bottom or attaching to some substrate. There are carpenter mollusks that drill into rocks or wood. The sizes of bivalve shells vary: from 1 mm to 1.5 m in diameter. The largest marine mollusk is a representative of the above-described class - Tridacna gigantea, whose weight reaches 300 kg.

The structure of bivalves.

All bivalves have a similar structure. Unlike gastropods, in bivalves the body consists of a laterally flattened body and legs, and there is no head. Their calcareous shell has two valves (hence the name of the class), and is not twisted in a spiral, like those of gastropods. Outer layer The shell is horny and often has a layer of mother-of-pearl inside it. The shell valves are connected along the dorsal edge of the mollusk and close when the muscles in the mollusk's body, which are attached to the internal parties opposite doors. In most species, the shell valves have protrusions and indentations on the inside on the dorsal side (the so-called “lock”), which contributes to a tighter closure of the valves. The shell grows throughout the life of the mollusk, and on its surface concentric rings of annual growth are noticeable, reminiscent of tree rings. Many species of bivalves have a well-developed nacreous layer, so most marine species and rare freshwater species are capable of forming pearls.

The animal's body is entirely enclosed in a shell. The leg in most individuals has a wedge-shaped shape; in those representatives of the class that lead an absolutely motionless lifestyle, it is reduced (mussels) or disappears completely (oysters). In a dangerous situation, the mollusk retracts its leg and slams its shell shut. The body of the mollusk is covered with a mantle, its folds grow together and form siphons at the posterior end of the body. Through the inlet siphon, oxygenated water with nutrients enters the mantle cavity, and through the excretory cavity, the mollusk gets rid of undigested food residues and metabolic products. Under the mantle on both sides of the body there are respiratory organs - gills - of different structures. different types, in most bivalves they are gill plates. The digestive system of bivalve mollusks is represented by the mouth, esophagus, stomach, liver, intestines, and the anus opens into the mantle cavity. The circulatory system of these mollusks is not closed; the three-chambered heart, consisting of two atria and a ventricle, is located in the dorsal part of the body. The nervous system consists of three pairs of ganglia; the sensory organs (balance, tactile sensitivity, and in some cases the eyes) are underdeveloped. The excretory system is represented by two kidneys, the excretory ducts of which open into the mantle cavity.

Bivalves (Bivalvia) are distinguished by a shell consisting of two parts (valves). This class has several more names that characterize representatives of this class. For example, Lamellibranchia are elasmobranchia molluscs whose gills actually consist of plates. Acephala are headless mollusks that lost their heads during the process of evolution. Pelecypoda (axe-footed) - the name describes the shape of the bivalve limbs.

There are several species of bivalves that have names that describe them external features

Lifestyle Features

The second largest group of mollusks after gastropods consists of more than 20 thousand species. All these species are benthic, i.e. bottom-dwelling. Bivalve mollusks live at the bottom of reservoirs with fresh or salt water. Most Bivalvia are extremely slow or lead an almost immobile lifestyle.

For example, the speed of movement along the bottom of representatives of the species of river bivalve mollusks - toothless - is no more than 20−30 cm per hour. And oysters, for example, are attached to the substrate in the larval stage and are completely unable to move.

The establishment of such a slightly or completely immobile lifestyle was led by evolutionary changes associated with the disappearance of the head and radula (from the Latin radula - scraper, scraper, grater for scraping food) and the formation of developed lamellar gills.

Bivalve mollusks lead an inactive lifestyle at the bottom of reservoirs

The depths at which they live different kinds class Bivalvia, vary from the tidal coastal zone to sea depressions 10 km deep.

Bivalves feed on organic particles and small plankton. Filtering suspended water using gills, they implement two functions at once: breathing, absorbing oxygen from water, and feeding, filtering out edible particles.

Some groups of elasmobranchs have interesting adaptations to life on rocks. Species belonging to the genus Pholas have sharp teeth for drilling passages in stones at the front end of the shell. And another type of marine bivalve mollusk, called sea date (Lithophaga), although it does not have a drilling apparatus, is also capable of penetrating stones, dissolving them with acid, which is secreted by special glands.

Body and shell structure

The body of a mollusk is placed inside a bivalve shell, consisting of a torso and legs. The leg is a muscular part of the body with which mollusks move along the bottom or burrow into the ground. It often has a wedge-shaped shape and is able to protrude from the shell.

Inside the shell is the body of the mollusk

Many species, for example, the mussel (Mytilus), have a byssal gland in their leg, which secretes a substance that helps the mollusk attach to stones and similar substrates. The byssus is a strong thread. Some adult mollusks do not have such a gland, in which case it most likely was developed at the larval stage.

The shells of elasmobranchs can have different sizes and shapes. The smallest deep-sea mollusks do not grow more than 0.5 mm in length. But there are also giants, for example, tridacna - an inhabitant of coral reefs in tropical seas. The dimensions of this bivalve species can reach 1.4 m in length with a body weight of up to 200 kg.

Most species have a laterally flattened oblong body. But there are also species with an elongated worm-shaped or almost spherical shape. The sink can be symmetrical or have doors different sizes. Most representatives of bivalves have a lock on the shell valves, which prevents the valves from moving relative to each other.

Regardless of the shape and size, the sink consists of three layers:

• external - conchiolin;
• internal - limestone;
• the lower one is mother-of-pearl.

The sea shell of a bivalve mollusk is thicker than that of a freshwater inhabitant

The thickness and strength of the shell also varies among different species and depends on the living conditions. A large number of minerals in water allows the growth of a more durable calcareous skeleton, so marine bivalves usually have thicker shells than freshwater species. The part of the mollusk’s body adjacent to the valves secretes substances that make up the shell. Thus, over the course of life, the shell gradually grows larger. Among Bivalvia with a well-developed pearlescent layer, there are freshwater species (pearlfish, freshwater pearl oyster, etc.) and marine species (sea pearl oyster, etc.).

Practical significance of bivalves

People living in close proximity to the shores of seas and rivers have long used Bivalvia as food. And household utensils and jewelry were made from their shells and pearls. Many elasmobranchs are used for food. The most common types are:

• mussels (Mytilus);
• hearts (Cardium);
• oysters (Ostrea);
• scallops (Pecten).

Pearl fishing

When a foreign irritant enters the shell, a pearl is formed

Currently, mariculture of Bivalvia mollusks is widely developed, i.e. artificial breeding. They are grown for use as food or to obtain pearls.

Founded in 1907 in Japan, the company was the first to produce artificial pearls. For this purpose, Bivalvia was caught on the open sea, and only in the mid-50s was it possible to organize the cultivation of pearl mussels themselves.

Pearl oysters placed in a shell foreign objects gradually become enveloped in mother-of-pearl. And after 1-2 years, it is possible to extract finished pearls, which are carefully sorted by size and shade and sent to enterprises for the manufacture of jewelry.

Biological water treatment

The ability of Bivalvia shellfish to biofiltrate is considered a beneficial property of these living organisms. A trend that considers the possibility of using these animals for water purification is considered relevant. Mollusks are able to absorb and accumulate heavy metals in the tissues of their bodies and purify water from chemical and organic contaminants. The average activity of elasmobranchs when filtering water is about 1 liter per hour.

One of the most useful properties These organisms are able to purify water

The issue of protection and breeding of Bivalvia for their use as biofilters in fresh and sea ​​waters is considered by scientists as one of the most pressing issues. In areas where commercial breeding of elasmobranchs is established, high-quality biological purification of water occurs, accumulation of bottom silt occurs, a rich benthic fauna develops, and the overall productivity of the ocean increases.

Formation of sedimentary rocks

Dying mollusks form calcareous sedimentary rocks, which form layers on the sea and ocean floor that are the material for the formation of shell rock, marble, and limestone. Shell fossils are the forms on which age determinations of the Earth's strata are based.

Malicious representatives

First of all, Bivalvia mollusks damage hydraulic structures and sea ​​ships. Active development of special coatings that can protect ships and structures from fouling by pests is underway.

Some species of shellfish are pests

In the rivers and sea waters of the Black and Caspian Seas, where the bivalve mollusk of the species Dreissena Polymorpha lives, significant colonies of these animals can form, which attach to hydraulic structures. These animals live in water pipes and hydroelectric power turbines, causing blockages.

A well-known pest is the Bivalvia mollusk of the species Teredo navalis (or hornet), also called the shipworm. Found in Black and Far Eastern seas, reaches 18 cm in length and has a worm-like shape. The shell occupies only one end and is adapted for drilling wood. The mollusk damages wooden structures and the bottoms of ships. To combat woodworm, the tree is tarred.

BIVALVES BIVALVES

(Bivalvia), class of shellfish. Known since the early Paleozoic (modern D. m. - from the Lower Ordovician), they reached their greatest species diversity in the Cretaceous. The body (length from several mm to 1.5 m, weight up to 30 kg) is bilaterally symmetrical, consists of a laterally flattened torso and legs. There is no head (hence one of the names - Acephala). In most, the leg is wedge-shaped (hence another name - Pelecypoda), in primitive forms it has a crawling sole, in those leading a sedentary lifestyle it is reduced (mussels) or disappears completely (oysters). Many D. m. have a byssal gland on the leg, which secretes strong threads (byssus), with the help of which the mollusk is attached to the substrate. The body is covered with a mantle that hangs freely in two folds, which can grow together; at the posterior end of the body there is a pair of long or short siphons. The shell consists of two valves (from several mm to 1.4 m long), covering the body from the sides; in some, the inside is lined with mother-of-pearl. The edge of the valves bears projections (teeth) that form a lock, the structure of which is one of the systematic ones. signs. The valves are closed by 1-2 closing muscles (adductors), their antagonist - an elastic ligament - keeps the valves half-open. In some D. m. (pearl mussels, mussels, toothless mussels), foreign particles falling between the mantle and the shell valve are enveloped in layers of nacre and turn into pearls. The mouth is equipped with two pairs of blades. Stomach with a blind sac-like outgrowth containing crystalline tissue inside. stalk (takes part in digestion and supplies the mollusk body with oxygen under anaerobic conditions). The liver, unlike other mollusks, is three-lobed. Some (Solemyidae) (for example, Solemyidae) have a liver and digestive system. the system is completely reduced. The gills of primitive forms are double-pinnate, in some they turn into a muscular septum, and in most into gill plates (hence another name for D. m. - Lamellibranchia). The nervous system consists of three pairs of ganglia. Sense organs are poorly developed; in some (scallops), inverted eyes are located along the edge of the mantle or siphon; at the base of the gill plates there are primitive osphradia, and there are statocysts. The circulatory system is not closed. Most are dioecious, rarely hermaphrodites. In some forms, sexual dimorphism is pronounced (for example, Thecaliacon camerata). Fertilization is usually external. In many species development with a floating larva (veliger, glochidium). Some have developed care for offspring - bearing young in gills (Unionidae), in brood chambers (for example, Mineria minima). It is customary to distinguish 3 orders: equidentates (Taxodonta), heteromuscular ones (Anisomyaria), elasmobranchia proper (Eulamellibranchia), according to another system - 3 superorders with 14 orders, uniting 130 modern ones. families OK. 1000 genera, including tridacnae, dreissenas, mias, pinnae, foladas, cordates, macomas, trigonias, sharovkas, toothless ones. OK. 20,000 species (in the USSR in fresh water bodies there are 50 genera with 200 species, in seas and brackish waters there are about 160 genera with 400 species). Widely distributed in the world approx. from the littoral to the abyssal, as well as in fresh waters. Benthic sedentary animals. To the depths 100-200 m in biomass and population density are often b. including benthic fauna. Filter feeders, detritus and planktivores, rarely predators; Some (tridacna, solemia) have symbiosis with zooxanthellae and thiobacteria. Write many fish and other marine animals. Some marine drills drill into wood and stones; many participate in fouling, causing great damage to ships and hydrotechnical equipment. structures. Object of fishing (annual catch 2.9-3.1 million tons in 1978-80) and aquaculture. See also fig. in table 31 and 32.

.(Source: Biological encyclopedic Dictionary." Ch. ed. M. S. Gilyarov; Editorial team: A. A. Babaev, G. G. Vinberg, G. A. Zavarzin and others - 2nd ed., corrected. - M.: Sov. Encyclopedia, 1986.)

Class of mollusks. Includes approx. 20 thousand species, widely distributed in the World Ocean, as well as in fresh water bodies (e.g. toothless). Bivalves are bottom-dwelling, sedentary animals that inhabit marine and fresh waters. Their bilaterally symmetrical, laterally compressed body consists of a torso and legs (no head) and is entirely enclosed in a calcareous shell. It has two symmetrical doors (hence the name) long. from a few millimeters to 1.4 m. The outside of the shell is covered with a stratum corneum, and the inside is often lined with a layer of mother-of-pearl. The shell valves are connected by their dorsal edges and are closed with the help of two muscles passing through the body of the mollusk from one valve to the other. When the muscles are relaxed, the valves move apart, when they are compressed, they close. Inside the shell is the body of the mollusk itself, covered with a mantle that hangs freely from the sides in the form of two large folds. Under the mantle on each side there are 2 gills, between which the leg is located. Using their legs, the mollusks slowly (20-30 km/h) crawl along the bottom. In case of danger, they retract their legs and slam the sink. If a foreign particle (for example, a grain of sand) gets between the mantle and the shell valve, it becomes enveloped in nacre and turns into a pearl. The main suppliers of pearls are sea pearl oysters living in shallow waters in tropical seas. They are hunted and bred for pearls. Artificially bred scallops, as well as mussels and oysters, which form large clusters (so-called jars) and are used for food.

Bivalves feed by filtering small organisms and organic particles from the water passing through the mantle cavity. Water enters and exits through siphons (holes in the back of the mantle between the right and left folds).

.(Source: “Biology. Modern illustrated encyclopedia.” Chief editor A. P. Gorkin; M.: Rosman, 2006.)

See what "BIVALVES" are in other dictionaries:

Tridacna bivalves Scientific classification Kingdom: Animals Subsection ... Wikipedia

Bivalves- 17. Bivalve molluscs are filtering elasmobranch mollusks... Source: SanPiN 2.3.4.050 96. 2.3.4. Food and processing industry (technological processes, raw materials). Production and sale of fish products.… … Official terminology

- (Bivalvia) a class of bilaterally symmetrical aquatic invertebrate animals such as mollusks. The shell consists of 2 valves, covering the body of the mollusk from the sides. On the dorsal side, the valves are connected to each other by an elastic bridge with a ligament...

Tridacna (Trid... Wikipedia

MOLLUSCS, representatives of more than 80,000 species of INVERTEBRATE animals of the phylum Mollusca. These include the well-known snails, bivalves and squids, as well as many less known species. Originally inhabitants of the sea, mollusks are now... ... Scientific and technical encyclopedic dictionary

Soft-bodied (Mollusca), a type of invertebrate animal. They presumably arose in the Precambrian; From the Lower Cambrian several are already known. classes M. They probably originated from small-segmented worm-like ancestors (annelids) or directly from flat... ... Biological encyclopedic dictionary

The request "Clam" is redirected here; see also other meanings. Molluscs ... Wikipedia

- (Mollusca) (from Latin molluscus soft), soft-bodied, a type of invertebrate animal. 7 classes: Gastropods, Monoplacophorans, Armored molluscs, Gross-bellied molluscs, Bivalve molluscs, Spadefoot molluscs and ... Great Soviet Encyclopedia

Class of marine and freshwater shell mollusks. Shell (length from a few millimeters to 1.4 m) of 2 valves connected on the dorsal side. About 20 thousand species. Widely distributed in the world's oceans, as well as in fresh waters. They live on... ... encyclopedic Dictionary

Marine class and freshwater shell mollusks. Shell (length from several mm to 1.4 m) of 2 valves connected on the dorsal side. OK. 20 thousand species. Widely distributed throughout the world, as well as in fresh waters. They live on the bottom from shallow waters to... ... Natural science. encyclopedic Dictionary

Toothless and pearl barley

Toothless- genus Anodonta And Perlovitsa- genus Unio(type Molluscs, class Bivalves, or elasmobranch mollusks, family Unionidae) are widespread in fresh water bodies temperate latitudes molluscs, which we call shells. Toothless prefer reservoirs with standing or slowly flowing water with a muddy bottom, and Perlovitsy prefer flowing reservoirs with a sandy bottom. Toothless are also more sensitive to chemical pollution in water. For example, in our city on the Uy River there are both genera of mollusks: Toothless and Perlovitsy, and on the Uvelka River there are many Perlovitsy, but Toothless are rare.

Sink. The bilaterally symmetrical body of these mollusks is enclosed in bivalve shell. Perlovitsa's shell is up to 15 cm long, somewhat elongated, more durable than that of Toothless. The Perlovitsa shell valves are connected on the dorsal side by special teeth and grooves - the so-called lock. The Toothless shell is up to 20 cm long, usually thin-walled, more rounded, without locking teeth (hence the name - Toothless), the two shell valves are connected by an elastic ligament ligament. The shell valves of these mollusks are closed using two muscles-contactors.

The two shell valves of Toothless and Perlovitsa are connected to each other on the dorsal side, and on the ventral side, a muscular outgrowth of the abdominal wall of the body is pushed into the resulting gap - leg. Toothless and Perlovitsa, opening the shell flaps and sticking out a wedge-shaped leg, slowly crawl along the bottom of the reservoir, leaving behind a trail traced by their legs. The speed of movement is no more than 20-30 cm per hour.

Once again, pay attention to the mollusk shell: the shell distinguishes front end– wider and rounder, and rear end– narrower, pointed. The most convex part of the valve is called navel. Both navels right And left leaf form the top of the shell. The shell consists of three layers. Outer conchiolin– dirty greenish color, formed by organic matter conchiolin. If you scrape it, the middle one opens - porcelain-shaped layer white. The inner surface of the shell valves is covered mother-of-pearl layer. The porcelain and mother-of-pearl layers are composed of calcium carbonate crystals. Thin plates of the mother-of-pearl layer, when reflecting light rays, give a peculiar pearlescent shine. Please pay

pay attention to the curved lines on the surface of the shell, parallel to its top. This annual growth lines. As the mollusk grows, so does

sink. The top of the shell is its oldest part. By the number of annual lines, the age of the mollusk can be determined.

Body Toothless and Perlovitsa consists of torso And legs, but the head is not isolated. Covered body skin fold, which is called mantle. The mantle hangs from the sides of the body in the form of folds. On the dorsal side, the mantle fuses with the body of the mollusk. At the posterior end of the body, the free edges of the mantle grow together, leaving holes - siphons for input ( gill siphon) and output ( cloacal siphon) water from the mantle cavity. The outer epithelium of the mantle forms the shell valves. Between the mantle and the body is located mantle cavity, into which the anus, ducts of the kidneys and gonads open, the respiratory organs of Toothless and Perlovitsa (gills), and some sensory organs are also located there.

Musculature in mollusks it is well developed and consists of muscle bundles, although the muscle fibers are of a smooth type. The muscle bundles are especially strongly developed in the animal’s leg. Toothless and Perlovitsa also have well-developed two closing muscles that hold the shell valves.

Body cavity. Internal organs are located inside the body in parenchyma, but there are cavities filled with liquid (like the primary body cavity of Ascaris). Secondary body cavity – in general- partially reduced, the remnants of the coelom contain the heart (in pericardium) and gonads. Thus, the body cavity in mollusks is formed by the remains of the primary cavity and a greatly reduced coelom. This cavity is called mixed cavity, or myxocoelem.

Digestive system in Bezzubka and Perlovitsa it consists of the foregut, middle and hindgut. The foregut is presented mouth opening, oral cavity And throat. Please note: the mouth opening is located at the base of the leg (!), it is surrounded by oral lobes triangular shape. Food particles are various organic remains that enter the mantle cavity with the flow of water through the gill inlet siphon, stick together into lumps and are sent into the mouth opening of the mollusk. This way of eating is called filtration, and the animals Bezzubka and Perlovitsa, respectively, are filter feeders. The digestive system of Toothless and Perlovitsa lacks a radula and salivary glands, characteristic of other mollusks. Food from the oral cavity enters esophagus, opening in stomach. Midgut makes a few bends at the base of the leg, then moves into hindgut which ends anus. Mollusks have a digestive gland - liver. The liver of Toothless and Perlovitsa is very extensive, surrounding the stomach on all sides.

Type Molluscs class Bivalves

Nervous system in bivalves and in Bezzubka and Perlovitsa scattered-knot type. It is represented by three pairs ganglia(nerve ganglia) that are connected commissures(nerve cords). First pair of ganglia ( head ones) is located near the esophagus, the second ( foot) in - leg and third ( splanchnic) - under the posterior conchal closure muscle. Nerves extend from the nodes to various organs. The sense organs of Toothless and Perlovitsa are poorly developed: there are special receptors(nerve endings) providing skin sensitivity; there are balance organs - statocysts; around the mouth and in the oral cavity - chemical sense organs. Toothless and Perlovitsa have no eyes.

Circulatory system open, comprises hearts and blood vessels. The heart is located in the pericardial sac pericardium and consists of two atria and one ventricle. They depart from the ventricle arteries - vessels through which blood flows from the heart to all organs. Part of the way the blood passes not through the vessels, but through the cavities between internal organs. Then the blood flows through the venous vessels to the gills, gas exchange occurs and oxygenated blood returns to the heart.

Respiratory system. On both sides of the leg in the mantle cavity (i.e., between the body and the mantle) in Bezzubka and Perlovitsa there are two lamellar gills. The gills, as well as the inner surface of the mantle, are equipped eyelashes, the movement of which creates a current of water. Through the lower (introductory, or gill) siphon, water enters the mantle cavity. Water is removed through an outlet (cloacal) siphon located on top. The gills are penetrated by a dense network of blood capillaries, where gas exchange occurs. Along with the flow of water, food particles also enter the mantle cavity through the inlet siphon.

Excretory organs at Bezzubka and Perlovitsa - kidneys, which are modified metanephridia (the so-called kidneys metanephridial type). Each kidney consists of numerous tubules. The tubule begins as a funnel in the pericardial sac (in the coelomic cavity), and the other end of the tubule opens into the mantle cavity. The kidneys are located under the heart.

Reproduction. Toothless and Perlovitsa dioecious, although there are no external gender differences. Testes And ovaries(male and female gonads) paired. The reproductive ducts coming from the gonads open into the mantle cavity. Fertilization in Toothless and Perlovitsa external in the mantle cavity. Here, eggs are attached to the female’s gills, which are fertilized by sperm that penetrate into the mantle cavity with a flow of water through the gill (introductory) siphon. After some time, the larvae of Bezzubok and Perlovits emerge from the eggs, which are called glochidia. Glochidia have a bivalve shell with jagged spines on the edges and a sticky byssal thread. When a fish swims over Bezzubka or Perlovitsa, adult mollusks push the larvae through the hatching siphon into surrounding water. Using a byssus thread and

Type Molluscs class Bivalves

Meaning. Toothless and Perlovitsy are an element biological diversity fresh water bodies are integral part food chains. In places where these mollusks are especially abundant, they become powerful natural water purifiers (biofilters). In some regions, people collect Toothless and Perlovits to feed poultry. In the old days, beautiful mother-of-pearl buttons were made from Perlowitz shells.

Questions for self-control

Name the aromorphoses of the Mollusc type.

Name the classification of the type Mollusks.

What's it like systematic position Toothless, Perlovitsy?

Where do Toothless and Perlovits live?

What is the difference between the Toothless and Perlovitsa shells?

What is the body structure of Toothless, Perlovitsa?

What is the body of Toothless and Perlovitsa covered with?

What body cavity is characteristic of Toothless and Perlovitsa?

What structure does it have? digestive system Toothless, Perlovitsy?

What structure does it have? circulatory system Toothless, Perlovitsy?

How does Toothless breathe, Perlovitsa?

What structure does it have? excretory system Toothless, Perlovitsy?

What structure does it have? nervous system Toothless, Perlovitsy?

What structure does it have? reproductive system Toothless, Perlovitsy?

How does Toothless and Perlovitsa reproduce?

What is the significance of Toothless, Perlovitsa?

Type Molluscs class Bivalves

Rice. Pearl barley: A - ordinary pearl barley; B - pearl barley swollen, or wedge-shaped; B - thick pearl barley.

Rice. Toothless.

Rice. Glochidium is the larva of Toothless and Perlovitsa.

Type Molluscs class Bivalves

Rice. Toothless's structure.

1 - Front edge; 2 - ventral edge; 3 - rear edge; 4 - dorsal, or key, edge; 5 - crown; 6 - external ligament; 7 - anterior closing muscle; 8 - posterior closing muscle; 9 - front leg retractor; 10 - protractor; 11 - rear leg retractor; 12 - leg elevators; 13 - leg; 14 - right fold of the mantle; 15 - introductory (gill, respiratory) siphon; 16 - excretory (cloacal) siphon; 17 - cloacal chamber; 18 - dorsal pallial canal; 19 - dorsal mantle opening; 20 - mouth opening; 21 - oral lobes; 22 - left outer hemibranch; 23 - left internal hemibranch; 24- area of ​​the Keber organ; 25 - pericardial area; 26 - line along which the left mantle fold is cut.

DRAWINGS THAT NEED TO BE COMPLETED IN THE ALBUM

(3 pictures in total)

Lesson topic: Type Shellfish- Mollusca.

Type: Shellfish

Genus: Toothless - Anodonta

Genus: Perlovitsa – Unio

Rice. 1. Toothless (Perlovitsa). External building.

1-sink 6-top sink

2-leg 7-inlet (gill) siphon

3-front end 8-lead (cloacal) siphon

4-back end 9-back side

5-ligament (ligament) 10-ventral side

Lesson topic: Type Shellfish- Mollusca.

Type: Shellfish

Class: Elasmobranchs, or Bivalves

Order: True elasmobranchs

Genus: Toothless - Anodonta

Genus: Perlovitsa - Unio

Rice. 2. Toothless (Perlovitsa). Internal structure.

1 - shell 11 - intestine

2-mantle 12-anal hole

3-leg 13-liver

4-inlet siphon (gill) 14-heart

5-lead siphon (cloacal) 15-pericardium
6-posterior closing muscle 16-kidney
7-anterior terminal 17-lead kidney opening

muscle 18-head ganglion (cerebral)

8-mouth lobes 19-legged ganglion (pedal)

9-mouth 20-splanchnic ganglion

10-stomach (visceral)

21 - sex gland (gonad)

Lesson topic: Type Shellfish- Mollusca.

Rice. 3. Glochidium – larva of Toothless and Perlovitsa.

1 - closing muscle; 2 - cloves; 3 - byssal thread.