Interesting facts about shellfish. Interesting facts about molluscs Meaning of gastropods presentation

Tasks:

1. To acquaint students with the diversity, organization and significance of gastropods.
2. To teach to establish cause-and-effect relationships between structural features, life activity and habitat of snails.
3. Develop the ability to listen carefully, analyze information.
4. Activate cognitive activity students through independent work on assignments.
5. Continue to teach children to recognize organs, organ systems of mollusks in drawings, diagrams and name them.
6. Develop a desire to know the animal world.

Equipment:

• a computer,
• projector,
• screen,
• separate material "Sinks of gastropods" (one per desk)
• DI. Traitak, S.V. Sumatokhin. Biology: Animals. Grade 7: Textbook for general education. institutions. - M.: Mnemosyne, 2008
• THEM. Gufeld. Zoology Grade 7: Workbook, 1997

Lesson plan:

I. Organizational moment and motivation of students' activities.

Checking knowledge on the topic " general characteristics shellfish":

1. 1-2 students complete a test on a computer. At this time, 1-2 students tell the general characteristics of mollusks at the blackboard (from paragraph 15 of the textbook).

2. Front work according to the interactive scheme "Structure of organ systems of mollusks" and the simulator "Systems of organ mollusks".

II. Learning new material.

1. Actualization of the topic, the purpose of the lesson (the teacher sets the relevance of the topic and designates the problematic issue of the lesson. Students write the topic of the lesson and homework. Slides 1-2, presentation).

2. Characteristics gastropods. (Teacher's story with elements of a slide conversation: slide 3 - the number of snail species; slides 4-12 - snail habitat; slides 13-15 - body structure. Working with handout“Gastropod shells” (students look at gastropod shells under the numbers indicated on slide 16 - gastropod shells). Slide 17 - respiratory organs and food specialization).

Dynamic pause.

3. The structure and lifestyle of the common pond snail, grape snail and field slug. ( Independent work by options: read and tell the text of the textbook on pages 64-65 about the structure and lifestyle of gastropods. Students' story. Discussion of the question: what is common in the structure of the studied mollusks. slides 19-20).

4. Sea shellfish: predatory snails cone and murex, planktonic gastropod - angelfish. (Teacher's story with elements of conversation on slides: 21-23).

5. Relationship between structural features, life activity and habitat of snails. (Front discussion of the problematic issue: what is the relationship between the structural features, life activity and habitat of snails. Students write down the features of adaptation to the habitat of gastropod mollusks. Slides 24 - 25.)

6. The value of snails in nature. (Story-conversation. Slide 26.)

7. The value of snails in human life. (Story-conversation. Slide 27. Independent work on assignment: from the article “Do you know?” on p. 45 workbook to find the answer to the question of what significance kauri and murex mollusks have in human life. Slide 28 - 29.)

III. Consolidation of the studied material(discussion on the questions: slide 30. Performing a test followed by self-assessment: slides 31-32).

IV. The result of the lesson, grades for the lesson.

TYPE OF
M O L L Y U S K I Performed by: Gurov Anton
7 B class, school number 49

Moscow 2011

Lecturer: Khanova I.B.

ORIGIN OF SHELLS

The problem of the origin of the type of molluscs is debatable. Some biologists derived a hypothetical ancestor of mollusks from annelids, others from flatworms.
At present, the most common hypothesis is the origin of mollusks from primary coelomic trochophore animals, from which annelids also originate. Some say about the relationship of mollusks and annelids common features organizations. So, a number of lower mollusks have retained the features of metamerism and have a scalene nervous system. The ontogenesis of mollusks also shows similarities with annelids inherited from common ancestors (spiral fragmentation, metamerism of some rudiments, etc.)

MAIN CHARACTERISTICS OF SHELLS I

SHELLS - a large type of animals in terms of the number of species (130 thousand). They live mainly in the seas (mussels, oysters, squids, octopuses), fresh water bodies (toothless, pond snails, livebearers), less often in a humid terrestrial environment (grape snail, slugs).
Body dimensions of adult molluscs different types differ significantly - from a few millimeters to 20 m. Most of them are sedentary animals, some lead an attached lifestyle (mussels, oysters), and only cephalopods able to move quickly in a jet way.
Mollusks are bilaterally symmetrical animals, however, in some mollusks, due to a peculiar displacement of organs, the body becomes asymmetrical. The body of mollusks is unsegmented, only in a number of lower representatives some signs of metamerism are found.
Mollusks are secondary cavitary animals with a non-metameric residual coelim, which in most forms is represented by a pericardial sac (pericardium) and a cavity of the gonads. All spaces between organs are filled with connective tissue.

MAIN CHARACTERISTICS OF SHELLS II

The body of mollusks, as a rule, consists of three sections - the head, trunk and legs. Very often, the body grows on the dorsal side in the form of an visceral sac. Leg - a muscular unpaired outgrowth of the abdominal wall of the body, serves for movement. The base of the body is surrounded by a large skin fold - the mantle. Between the mantle and the body is the mantle cavity, in which the gills, some sensory organs lie, and the openings of the hindgut, kidneys and reproductive apparatus open. All these formations, together with the kidneys and heart (located in close proximity to the mantle cavity) are called the mantle organ complex. On the dorsal side of the body, as a rule, there is a protective shell exuded by the mantle, more often whole, less often bivalve, or consisting of several plates.
Most mollusks are characterized by the presence in the pharynx of a special apparatus for grinding food - a grater (radula). The circulatory system is characterized by the presence of a heart, consisting of a ventricle and atria; it is not closed, i.e. part of its path, the blood passes through a system of lacunae and sinuses that are not formed into vessels. The respiratory organs are usually represented by primary gills - ctenidia. The latter, however, disappear in a number of forms or are replaced by respiratory organs of a different origin.

SHELL HABITATION

Mollusks live in rivers, seas, oceans and other bodies of water, as well as on land - in fields, forests and other land plots.

STRUCTURE OF SHELLS

BODY
The body of mollusks does not show signs of true segmentation, despite the fact that some organs (for example, gills of chitons and monoplacophores) may be characterized by a serial structure.
The body of mollusks, as a rule, consists of three sections: head, legs and torso. Representatives of the class Caudofoveata have no legs. Bivalves, on the other hand, lose their heads a second time.
The leg is a muscular, unpaired outgrowth of the abdominal wall of the body, and, as a rule, serves for movement.
The trunk contains all the major internal organs. In the Conchifera group, it grows strongly on the dorsal side during embryonic development, resulting in the formation of the so-called visceral sac.
The mantle extends from the base of the body - an epithelial fold that forms a mantle cavity associated with external environment. The so-called mantle complex of organs is located in the mantle cavity: the excretory tracts of the sexual, digestive and excretory systems, ctenidium, osphradium and hypobranchial gland. In addition, the mantle complex of organs includes the kidney and pericardium, located next to the mantle cavity.

STRUCTURE OF SHELLS

COVERS
It is believed that in the hypothetical ancestor of mollusks, the integuments were represented by the so-called protoperinotum: a cuticle with aragonite spicules. A similar structure of integuments is characteristic of representatives of the classes Caudofoveata and Solenogastres. However, all classes of molluscs, except Caudofoveata, have a ciliary creeping surface - a leg (on this basis, they are combined into the Adenopoda group). In Solenogastres, the foot is represented by a pedal furrow.
Chitons (Polyplacophora) also have cuticular covers, but only on lateral surfaces called perinatal folds. The dorsal surface is covered by eight shell plates.
In the Conchifera group (which includes the classes Gastropoda, Cephalopoda, Bivalvia, Scaphopoda, and Monoplacophora), cuticular covers are absent, and the shell consists of a single plate.

Slide #10

Slide #11

STRUCTURE OF SHELLS

NERVOUS SYSTEM
The nervous system of molluscs is tetraneural. It consists of a peripharyngeal ring and four trunks: two pedal (innervates the leg) and two visceral (innervates the visceral sac). However, this structure is typical only for the lower groups of mollusks: Caudofoveata, Solenogastres and Polyplacophora.
In most other representatives of molluscs, the formation of ganglia and their displacement to the anterior end of the body are observed, and greatest development receives the supraesophageal ganglion "brain". As a result, a nervous system scattered-nodal type.
Accommodation occurs due to a change in the shape of the eye - the distance or convergence of the retina and lens.
Smell and taste are not separated.

Slide #12

Slide #13

STRUCTURE OF SHELLS

CIRCULATORY SYSTEM
Open (with the exception of cephalopods). It includes the heart (an organ that ensures the movement of blood through the vessels and cavities of the body) and blood vessels. The heart consists of a ventricle and one or two atria (the nautilus has 4 atria).
Blood vessels pour blood into the space between the cells of organs. Then the blood is again collected in the vessels and enters the gills or lungs.
It is worth noting the unusual bluish color of the blood of mollusks. This color comes from hemocyanin, which performs functions similar to those of hemoglobin in the blood of chordates and annelids.

Slide #14

Slide #15

STRUCTURE OF SHELLS

Slide #16

Slide #17

STRUCTURE OF SHELLS

EXTRACTION SYSTEM
One, more often two kidneys, in which excretory products accumulate in the form of lumps of uric acid.
They are displayed every 14-20 days.

Slide #18

STRUCTURE OF SHELLS

REGENERAL SYSTEM
Mollusks can be either hermaphrodites (snails) or dioecious (toothless).
Development can be direct or indirect.
The larvae of some mollusks are called sailfish, or veliger, as they resemble a sail.

Slide #19

Slide #20

VARIETY OF SHELLS

Slide #21

CLASSES OF SHELLS I

Gastropoda, a class of invertebrates such as molluscs.
The body is divided into head, sac and leg. The head bears 1 or 2 pairs of tentacles and a pair of eyes. The visceral sac and the shell covering it are spirally twisted to the right or (rarely) to the left (asymmetric animals).
The shell is distinguished by a wide variety of shapes and sculptures: from high-conical to flat-spiral and saucer-shaped; consists of three layers: outer - horny, middle - porcelain-like and inner - mother-of-pearl. In some gastropods, the shell becomes internal or disappears.
The front part of the visceral sac is bounded from the outside by a skin fold - the mantle. The mantle cavity contains a complex of organs, consisting in primitive forms of symmetrically lying: rectum with anus, two hypobranchial glands, two ctenidia, two osphradia (organs of chemical sense), a heart with two atria and two kidneys.

Slide #22

CLASSES OF SHELLS II

Slide #23

Slide #24

CLASSES OF SHELLS III

Lesson topic: gastropods .

(snails)

The purpose of the lesson:

• To get acquainted with the taxonomy of molluscs and their meaning.
• Show the complication of the level of organization of molluscs compared to annelids.
• Identify the features of the structure, life and origin of mollusks.
• Continue the formation of skills to analyze; establish causal relationships.

• Prudovik

• Coil horn

land molluscs

grape snail

Yantarka

Sea shellfish

• kauri

miter

Cone

Murex

Signs for comparison

gastropods

habitats

Bivalves

Sink

cephalopods

Division of the body into sections

organs of movement. Way to travel.

Lifestyle.

Type of food.

The method of getting food.

Breath

Most snails form open spiral shells when all its whorls are visible from the outside

In some snails, the last larger whorl covers all the previous ones. Such shells are called cryptospiral

kauri(Eng. Cowry) - shells of tropical mollusks used as money on the islands of Oceania. Kauri is a marine gastropod mollusk of the cyprian family (Cypraeidae). The peoples inhabiting the coastal regions have known them for several thousand years. Cowrie shells are known to have been used as money in China, India, the Arabian Peninsula and Africa. It was believed that they protect from evil, and therefore cowrie shells, their clay models were put into the walls of buildings and into graves. The tiger kauri is perhaps the most famous among the other species. Large sizes, with a shiny surface and a large spot on the shell, it attracts the eye of even a casual observer. Kauri are predators that feed on soft-bodied creatures that live on rocks. The foot wraps almost completely around the shell as the clam moves, and the siphon sticks out at the front like a small periscope. Female kauri lay their eggs in small capsules, attaching them in clusters to rocks. They guard these capsules by covering them with their foot until the offspring hatch.

Murex

Mureks, or crimsons, is one of the most popular groups among collectors. The shells of these snails are decorated with numerous outgrowths, ridges or spikes and are brightly colored. Many murex reach impressive sizes. Representatives of the family are distributed throughout the World Ocean from the polar latitudes to the equator, but the brightest and most large species inhabit tropical zone. Murex are carnivorous snails. Their victims are bivalve mollusks, the valves of which they drill through with their radula.

Cone- a predatory snail, moreover, poisonous. They hunt with the help of a tooth - they pierce the victim with it, like with a harpoon. They feed on sea worms, mollusks and small fish. They can sting no worse than a bee - and the consequences can be quite unpleasant. Even possible death. There are about 600 types of cones. They are concentrated in tropical seas and oceans around the world. Most of cones lives on or near coral reefs. The snail gets its name from its bullet-shaped shell. In many of the cones, the surface of the shells is brightly colored. Of course, the shell is heavy, and the "leg" of the snail is only one, so these animals move extremely slowly. Which forces them to stop fast-moving prey with a poisonous harpoon. This harpoon is a modified tooth. But in general, teeth (in snails they are called radulas) are needed in order to better grind and digest food. Each tooth is in the back wall oral cavity. The snail paralyzes the victim, the radulas draw it in, grind it. And indigestible material, including a disposable harpoon, remaining in the body of the victim, the snail spews back. Another tooth becomes a harpoon. In snails, they grow constantly.

Check

• Segmented.
• Head, body, leg.
• Mantle.
• Atrium (sometimes two) and ventricle.
• mantle cavity.

• Attachment of muscles, external skeleton, protection.
• Gastropods.
• Tongue with a "grater", liver.
• Open.
• Bud.
• Atmospheric.

Homework: 11.

Creative task:

• 1. Write a biological essay about the molluscs of Belarus.
• 2. Prepare a presentation on the diversity of shellfish.

Attach clam shells to the board using magnets according to your feelings:

White: learned everything, it was interesting

Orange: not understood everything, puzzled

Yellow: did not understand anything, tired

Reflection

Presentation on theme: "Mollusks. Gastropods. "Performed by: Student of the MAOU "Lyceum No. 28 named after. N.A. Ryabova" 7th class "B" Ermilova Elizaveta

Grape snail.

Origin of shellfish. The origin of mollusks - the ancient inhabitants of our planet - appeared about 450-500 million years ago. Among their characteristic features, a calcareous shell is noted. Mollusks are a large type of animals in terms of the number of species (130 thousand). Their ancestors appear to have been flatworms. Mollusks live mainly in the seas (mussels, oysters, squids, octopuses), fresh water bodies (toothless, pond snails, livebearers), less often in a humid terrestrial environment (grape snail, slugs). The body sizes of adult mollusks of different species vary considerably - from a few millimeters to 20 meters.

Mollusks are divided into 3 classes: Gastropods Cephalopods Bivalves

Gastropods.

The gastropod class is the only class whose representatives have mastered not only water bodies, but also land, therefore, in terms of the number of mollusk species, this is the most numerous class. Its representatives are relatively small in size: the Black Sea rapana mollusk is up to 12 cm tall, the grape snail is 8 cm, some naked slugs- up to 10 cm, large tropical species reach 60 cm.

External and internal structure.

The gastropod mollusks are slugs, which got their name because of the abundant secretion of mucus. They don't have sinks. They live on land in humid places and feed on plants, fungi, some are found in vegetable gardens, causing harm to cultivated plants.

Field slug.

Interesting and educational.

1. The largest clam ever caught weighed about 340 kilograms. It was caught in Okinawa, Japan in 1956.

2. The oldest mollusk caught by man, according to scientists, was around 405 years old, it may have been the oldest marine animal3. The age of mollusks can be determined by the number of rings on the shell valve. Each ring differs from the previous one due to the characteristics of the food consumed during this period, the state of the environment, temperature and the amount of oxygen in the water.

6. An oyster can produce about a million eggs in one season. However, only a few will be able to survive and grow to adulthood.

7. Some varieties of scallops have dozens blue eyes along the edges of the shell. With the help of them, scallops can notice predators and escape in time. 8. Bivalves can move around. Scallops, for example, by rhythmically squeezing the valves and throwing out a jet of water, can swim far enough away from their enemies - starfish.

Thank you for your attention!