Interesting facts about shellfish. Interesting facts about mollusks Download ppt "Gastropods"

"Description of molluscs" - Malacology. Luzhanka. Ammonites. Explain the errors in the statement. Variety of shellfish. Characteristic features of molluscs. Mollusk classification. Squid. Write down the numbers of the correct statements. Some species do not have a shell. Ways of movement. Body parts of molluscs. Laboratory work. Shellfish.

"Octopus" - It all depends on the temperature of the surrounding water. The octopus breeds twice a year mainly in spring and autumn. Bivalves. Octopuses. The octopus lives in shallow waters up to a hundred meters deep, prefers a rocky bottom. The octopus hunts mainly at dusk and in the evening. Octopus. The intelligence of octopuses is much higher than that of a number of other vertebrates.

"Class Gastropods" - Blood vessels. Lung. The pond snail has 3 distinct body parts. Nervous system. In connection with the asymmetry of the body, there is an underdevelopment of the organs of the right side of the body. Class Gastropoda molluscs (Gastropoda). Nerve trunks of internal organs. Anal opening. Blood vessels develop in the mantle and the mantle cavity becomes the lung cavity.

"Characteristics of classes of mollusks" - General characteristics. Types of shellfish. Grape snail. Angelfish. Methods of feeding molluscs. The role of mollusks in ecosystems. Class Cephalopoda. Shellfish. Type: Shellfish. Class Gastropoda. Bivalve class.

"Echinoderms" - Ancient animals that existed for 500 million years. Type Echinoderm. Almost all are protected by a shell formed by a skin fold - the mantle. The withdrawal of more than 150 thousand tons is calculated. Target. Getting acquainted with today's material, you need to fill in the data in the tables. Subkingdom Multicellular. Table 1. "The value of shellfish."

In total there are 17 presentations in the topic

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.
Currently, the most common hypothesis is the origin of mollusks from primary coelomic trochophore animals, from which annelids also originate. Some common features of organization speak of the relationship of mollusks and annelids. 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).
The body sizes of adult mollusks of different species vary significantly - from a few millimeters to 20 m. Most of them are sedentary animals, some lead an attached lifestyle (mussels, oysters), and only cephalopods are 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 a number of lower representatives show some signs of metamerism.
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 the external environment. The so-called mantle complex of organs is located in the mantle cavity: the excretory tracts of the reproductive, 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.

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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 mollusks, the formation of ganglia and their displacement to the anterior end of the body are observed, with the supraesophageal ganglion "brain" receiving the greatest development. As a result, a scattered-nodular nervous system is formed.
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.

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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.

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STRUCTURE OF SHELLS

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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.

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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.

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VARIETY OF SHELLS

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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, which in primitive forms consists of symmetrically lying rectum with an anus, two hypobranchial glands, two ctenidia, two osphradia (chemical sense organs), a heart with two atria, and two kidneys.

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CLASSES OF SHELLS II

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CLASSES OF SHELLS III

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 the cognitive activity of 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 of molluscs":

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. Frontal work according to the interactive scheme "The structure of mollusk organ systems" and the simulator "Mollusk organ systems".

II. Learning new material.

1. Actualization of the topic, the purpose of the lesson (setting by the teacher of the topicality of the topic and designation of the problematic issue of the lesson. Students write down the topic of the lesson and homework. Slides 1-2, presentation).

2. Characteristic features of gastropods. (Teacher's story with elements of conversation on the slides: slide 3 - the number of species of snails; slides 4-12 - the habitat of snails; slides 13-15 - the structure of the body. Working with the handout "Gastropod shells" (students examine gastropod shells under 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 on 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. Marine mollusks: 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 record 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 the assignment: from the article “Do you know?” On page 45 of the workbook, find the answer to the question of what importance 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.

Gastropods, or snails, are the richest class of mollusk species in representatives. Most gastropods are marine animals. Some representatives of this class in the course of evolution adapted to life in fresh water, others switched to terrestrial existence. In the seas, gastropods are found at various depths, on land in a variety of climatic conditions. They are tolerant of high and low temperatures, due in part to their ability to hibernate: in the north in winter, in the south in summer, and often in winter.

The body shape of gastropods is varied. The head is clearly separated from the body, bears 12 pairs of tentacles and a pair of eyes. The foot is well developed and usually has a wide crawling sole. The trunk forms an outgrowth in the form of a large visceral sac. A characteristic feature of all gastropods is the asymmetry of the structure, resulting from the formation of a spirally twisted shell. The sizes of gastropods range from 23 mm to several centimeters (grape snail, slug, pond snail

The mouth of mollusks leads into the oral cavity, which passes into the muscular pharynx, in which the tongue with the radula is located. In addition, there are local thickenings of the cuticle (the so-called jaws) in the oral cavity. The ducts of one pair of salivary glands open into the pharynx. The pharynx passes into the esophagus, some at its end an extension is formed - a goiter. The middle intestine has an extension - the stomach, followed by the small intestine, passing into the back, ending in powder. In some lower gastropods, the hindgut passes through the ventricle of the heart. The liver secretes secrets that promote the digestion of food (mainly carbohydrates), in addition, the liver is able to absorb food and store glycogen and fats in it.

Most gastropods have one left atrium (the right one is sometimes completely reduced) and one ventricle. The heart of molluscs is surrounded by the pericardium. The aorta departs from the ventricle, which soon divides into the head aorta and the splanchnic aorta (goes to the intestines, liver and sex gland). From the branches of the arteries, the blood enters the lacunae, loses oxygen and collects in the venous lacunae, from here the blood returns to the gills or the lung and, having been oxidized, goes directly to the heart.

The nervous system of animals consists of several pairs of ganglia connected by commissures. Gastropods have eyes, organs of balance statocysts, organs of touch (tentacles) and chemical sense. The excretory system of mollusks consists most often of one left kidney, one end communicating with the pericardium, and the other opening into the mantle cavity on the side of the powder.

Among the gastropods there are dioecious animals and hermaphrodites (snail). They always have one sex gland, fertilization is cross, and in hermaphrodites, each individual functions both as a male and as a female. Fertilization in most animals is internal. In lung molluscs, development is direct and proceeds to the end in the egg shell, in the rest - with the formation of a larva (trochophore or sailboat).

The economic importance of gastropods is small. Slugs and grape snails are agricultural pests. But grape snails in some countries, especially in France, are considered a delicacy and are specially bred. Many large sea snails (trumpeters) are also eaten. The shells of species with a well-developed mother-of-pearl layer are used for making jewelry.

In the old days, special cowrie shells in the southern countries served as a bargaining chip. A number of gastropod species are the first intermediate hosts of parasitic flatworms, which are also dangerous for humans. Two genera of tropical molluscs, cone and terebra, have poisonous glands and can seriously “sting” a careless person who picks them up.