Presentation to the lesson on the topic "Cartilaginous fish". Conducted in 7th grade. Each slide reflects the main points of the study new topic. The children liked the anglerfish the most among the cartilaginous representatives))))))))).

View document contents
“Presentation for the lesson Cartilaginous fishes”

Superclass of fish.

Class Cartilaginous fish

Ichthyology (from Greek. ichthys- fish, logo- doctrine) - a branch of zoology that studies fish.

External structure of fish

Body Shape

Body covered

Body parts

Organs of movement

Determining the direction of water movement

streamlined

scales and mucus

head, body, tail

fins

Side line

Internal structure fish

gills.

one circle of blood circulation two-chambered heart.

trunk buds.

head dorsal

Superclass Pisces

Cartilaginous fish

Bony fish

The class Cartilaginous fish has about 750 species.

Main features:

1. Cartilaginous skeleton

2. No gill covers

3. No swim bladder

4. Scales with teeth covered with enamel (placoid)

5. Pointed head shape

Cartilaginous fish

subclass

Elasmobranchs

(sharks and rays)

subclass

Whole-headed

Laboratory work External structure of fish

1. Consider the external structure of the fish. Sketch.

2. Find: head section, gill cover, lateral line, fins, tail.

3. Label the found parts of the body in the drawing.

4. Conclusion: Fill out the table “adaptation of the external structure of fish to living in water.”

Fin

Origin

On the left is one of the armored fish - bothriolepis.

On the right are the jaws of a fossil Carcharadon shark.

• ancient group of fish.
• Sharks and rays
• 600 species
• Cartilaginous skeleton
• The body is covered with bone scales

• Sharks include fish with an elongated torpedo-shaped body and a length of 20 cm to 20 m. The skin of sharks is rough, covered with numerous denticles. The paired pectoral and pelvic fins are located horizontally and allow the fish to move up and down. There are underdeveloped eyes on the head, capable of seeing objects only in black and white.

• The respiratory system begins with 5–7 pairs of gill slits.
• In the intestine, a spiral valve stretches along its entire length, increasing the absorption surface.
• The arterial cone of a two-chambered heart is capable of independent contraction and provides an additional impulse of blood.
• The sense organs are represented by the organs of smell, vision, touch (lateral line)
• Fertilization in almost all cartilaginous fish is internal.
• Many of them have a cloaca.
• Cartilaginous fish are viviparous or lay eggs.

The most dangerous sharks

White shark

Hammerhead shark

• These are relatively large fish, some of them reach a width of 6 - 7 meters and a mass of 2.5 tons. Their body is flat, flattened in the dorso-ventral direction, diamond-shaped - with pectoral fins fused and expanded on the sides. The caudal fin has the appearance of an elongated thin whip. The skin of some stingrays is smooth, but many of them have scales and spines similar to those of a shark.

• Gill slits are located on the ventral side
• The body is strongly flattened.
• Wide pectoral fins grow to the edges of the body and head. The caudal fin is thin, and its blades are often reduced. The anal fin is absent.
• They use their pectoral fins to move, flapping them like wings.
• The squirts are much better developed than those of sharks.
• Most species are inhabitants of the seabed, which is why their backs have a protective color that matches the color of the soil.
• Stingrays reproduce by laying capsuled eggs on the bottom or by viviparity.

• Some species of stingrays have electrical organs.
• The discharge lasts 0.03 seconds with a voltage of up to 220 V.

European chimera

American hydrolag

• The jaws are completely fused with the skull.
• The gill slits are covered by a fold of skin.
• There is no cloaca, the anal and urogenital openings are separated from each other.
• The naked body is up to 1.5 m long, gradually becoming thinner, turning into a long tail.
• They live from the shelf to the great depths of the World Ocean.
• Chimeras feed on marine invertebrates and fish.
• They have practically no commercial significance.

Test task "Wave"

1) in cartilaginous fish, the gills are closed by cartilaginous

lids;

3) most rays are bottom-dwelling

4) sharks and rays lead a bottom-dwelling lifestyle;

5) all sharks are dangerous to people;

6) cartilaginous fish have highly developed muscles;

7) cartilaginous fish have a swim bladder;

8) the skin of cartilaginous fish is covered with scales;

9) the body of stingrays is torpedo-shaped;

10) the coloring of stingrays is protective.

Description of the presentation by individual slides:

1 slide

Slide description:

Class Cartilaginous fish Lesson objectives: To develop students’ knowledge about cartilaginous fish. Objectives: 1. To introduce students to the diversity of cartilaginous fish. 2. Study the characteristics of the class and orders of cartilaginous fish. 3. Broaden the horizons of students and cultivate a caring attitude towards nature. 4. Develop skills and abilities to work with additional literature and create presentations

2 slide

Slide description:

3 slide

Slide description:

Signs of cartilaginous fish (more than 1100 species) The most primitive modern fish. A) cartilaginous skeleton B) gill slits C) no gill covers D) no swim bladder E) mouth on the lower part of the head E) internal fertilization G) cloaca Characteristic representatives of cartilaginous fish are sharks and rays.

4 slide

Slide description:

Sharks The body is elongated, fusiform - paired fins are located horizontally - the skin is rough, the scales are placoid - 5-7 gill slits on the sides of the body - unequally bladed caudal fin - poor vision - lead an active lifestyle. They live in seas and oceans. Tiger shark, hammerhead shark, white shark.

5 slide

Slide description:

Stingrays Stingrays (350) The body is flattened, diamond-shaped, the pectoral fins are fused, the caudal fin is in the form of a whip, there are no gill covers, there is no swim bladder. Seas and oceans. Manta ray, stingray, spotted eagle.

6 slide

Slide description:

Chimeras Chimera-like (30) The anterior section of the body is developed, the caudal section ends with a thread-like appendage, the skin is smooth, there are no gill covers, and there is no swim bladder. Seas and oceans. European chimera, long-nosed chimera.

7 slide

Slide description:

8 slide

Slide description:

The length of the tooth of the oldest shark reached 17-18 cm. The number of shark teeth can range from 30 to 15,000 pieces. In one decade of life, a shark replaces up to 24 thousand of its teeth. The largest shark has the smallest teeth - the size of a whale shark's fang is only 6 mm. The jaw of a great white shark consists of teeth, the length of which is 5 cm. Shark teeth are the only bone tissue in a predator, everything else is cartilage. In view of this, shark fossils from prehistoric times are, as a rule, teeth. A great white shark's teeth can rotate inward by 16 degrees when the predator opens its mouth more than a third. At the moment of a bite, the shark's upper and lower teeth extend forward 9 degrees. Scientists are inclined to believe that a shark can use its teeth to determine the fat content of the prey and its suitability for food. Each type of shark has its own teeth, both in shape and size. This serves as a reliable source of identification of individuals in cases of attacks and other incidents. Sometimes the scales of predators are also called “skin teeth”. All shark skin scales are covered with a special enamel (vitrodentin), just like its teeth, which gives them special strength.

Slide 9

Slide description:

The force of compression of the jaws of a white shark is about 600 kg/cm2. The white predator can easily bite through thin steel rods. According to US statistical services, in the first decade of the 21st century, 244 great white shark attacks were known since... the end of the 16th century, and only 65 episodes were fatal. Only in 1873 did the great white shark receive its “official” name in Latin - Carcharodon; before that it was called differently everywhere. Carcharodon becomes a superpredator only in the 7th year of life, when its jaw acquires powerful teeth. A juvenile great white shark feeds exclusively on fish. The great white reaches sexual maturity at the age of 15 years, and the average lifespan of a white shark is 30 years. There is a known case when a great white shark itself completely jumped into a fishermen’s longboat (1936). The great white shark is itself a favorite meal of another large predator, the killer whale. At the last moment of the attack, the great white shark closes its eyes to protect them from the cat's claws. There are known caught specimens of the great white shark reaching a length of over 10 meters. At the same time, the weight of the huge predator reached 3.5 tons. Carcharodon parents do not train their young. Young predators must survive on their own.

10 slide

Slide description:

Less than half, namely only 47% of all great white shark attacks are successful. Carcharodon's hunting tactics and strategy include hours of tracking and waiting for a potential victim. On average, a great white shark eats 11 tons of food per year. Interestingly, a great white shark can be on the move without food for as long as three months, however, it can immediately after a hearty “lunch” go in search of a new victim. In captivity, Carcharodon refuses food, and therefore the death of great white sharks in captivity occurs on the 10th-11th day. There is only one known case in which a female Carcharodon lived in captivity for 200 days. This was in San Francisco, after this imprisonment the predator was released.

11 slide

Slide description:

It’s not for nothing that the tiger shark is called the “scavenger of the ocean.” This predator can eat anything it comes across. There are known cases when explosives, cannonballs and powder barrels, as well as various metals - cans, buckets and all sorts of small iron items were found in the stomach of a tiger shark. Tiger shark skin is 10 times stronger than bull hide. The tiger shark can compete on equal terms with the great white shark for primacy in the title of “killer shark”. The tiger shark is considered a nocturnal predator. There is an assumption that daylight bright light may disorient her. The tiger shark, unlike Carcharodon, will never abandon its prey, even if it is inedible. The tiger shark simply regurgitates all undigested objects in the stomach. Large tiger sharks have their equally voracious sand brothers. The stomachs of these predators can accommodate up to 50 kg of prey at a time. Sand tiger sharks are also called “burping” predators. The reason for this is their biology. This type of shark can specifically swallow air above the surface of the water and retain it inside itself, thus providing better body buoyancy.

12 slide

Slide description:

The most common type of shark is the dog shark, also known as the dogfish shark, or the spiny shark. The female katran bears her offspring longer than anyone except the frilled shark. Her gestation period is up to 22 months. The age of a katran can be determined by its “poisonous” thorn: in cross-section, it has the same “annual rings” as trees. It is known that katran liver contains 10 times more vitamin A than cod liver. It was with the katran shark that the mass fishery of sharks began. In a katran egg, the mass of the yolk exceeds the mass of a chicken yolk, and in Norway they also make flour from this shark, which consists of up to 85% pure protein. The “poisonous” katran thorn actually does not contain poison, but, nevertheless, an injection from such a thorn is dangerous for humans due to the harm of microorganisms that live in its mucus.

Slide 14

Slide description:

Shark eggs A whale shark egg is larger than an ostrich egg. Its rectangular egg measuring 35x60 cm was discovered in 1953 in the Gulf of Mexico. Sharks are known for their uterine cannibalism: young ones that have not yet been born can eat each other. Uterine cannibalism kills up to 70% of young sharks. These poor fellows do not live to see their birth. A hammerhead shark brood numbers about 30-40 babies at a time. Science knows several cases of parthenogenesis in sharks, i.e. reproduction without the participation of a male individual. Sharks do not show altered fertility and do not have any hereditary diseases. Sharks can “repair” their gene set themselves. The birth of mutants and freaks in the shark environment is rare, and such “damaged” individuals always remain viable. Puberty in large sharks ends by the 9-10th year of life. Medium and small predators are ready for annual mating, but great white and whale sharks give birth to offspring on average three times in 10 years.

Back forward

Attention! Slide previews are for informational purposes only and may not represent all the features of the presentation. If you are interested this work, please download the full version.

Lesson type: formation and consolidation of new knowledge.

Target: familiarization with the general characteristics of the class, the diversity and features of the structure and behavior of the orders of sharks, rays, and chimaeras.

Tasks:

• learn the main characteristics of cartilaginous fish;
• understand the classification;
• identify features of adaptation to the environment;
• learn the meaning in nature and in human life;
• be able to recognize representatives of the orders Sharks, Rays and Chimaeras;
• develop the ability to observe animals while watching a video clip;

Teaching methods:

According to the source of transmission and perception of educational information:

• verbal (story, conversation);
• visual (illustration, demonstration);
• practical (test, exercises).

By degree of educational work management:

• educational work under the guidance of a teacher;
• independent work students;
• working with a textbook;
• practical control and self-control.

Form of organization of educational activities of students:

• frontal
• individual
• steam room

Equipment:

• illustrations depicting representatives of the type,
• computer,
• screen,
• multimedia installation,
• Power Point presentation.

During the classes

I. Organizational moment.

- Let's sum it up. Slide 5

– Origin. Slide 6

• Related to ancient armored fish
• The primitive antiarchs had their entire body encased in a shell of skin plates;
• In carnivorous arthrodir the shell covered only the front part of the body.
• Armored fish are the first jawed fish; their jaws arose from gill arches that moved closer to the mouth, and consisted of pointed bony plates.
• Armored fish became extinct at the end of the Devonian.

2. Characteristics of units.

Sharks. general characteristics slides 7-8

Variety of sharks. Slide 9-13, film clips slides 10,slide 12

Gymnastics for the eyes slide 14

1. Blink quickly, close the gas and sit quietly, slowly counting to 5 (4-5 times)
2. Close your eyes tightly (count to 3) Open and look into the distance (count to 5) (4-5 times)
3. Make 3-4 circular movements with your eyes to the right side, then to the left. Look into the distance at the count of 1-6. (1-2 times)

Stingrays(Explanation by the teacher with elements of conversation.) slides 15-17

Look at the photo. What features of adaptation to the environment did you see?

Chimeraformes(Explanation by the teacher with elements of conversation.) slides 18-19

Additional material for teachers (See. Appendix 8)

IV. Consolidation of knowledge

slide 20

Work in pairs (check with each other)

Answer on the board

slide21

What order do these fish belong to?

Exchange rates