Presentation for the lesson on cartilaginous fish. Presentation "Cartilaginous fish" presentation for a biology lesson (grade 7) on the topic Presentation on the topic cartilaginous fish sharks

CARTILAGE FISH Svetlana Valerievna Veretennikova Biology teacher, Secondary School No. 19, Nizhny Novgorod

Cartilaginous fish are among the most ancient among fish. The first shark-like fish lived in the Devonian seas 410 million years BC. In the process of evolution, stingrays became flat, their lateral fins turned into peculiar wings, and they descended into the bottom layers of the world's oceans. These marine animals became active predators and colonized all areas of the ocean except for the great depths. With few exceptions, all cartilaginous fish live in salt water.

This terrible white predator is looking for food in the ocean. Sensitive nostrils on the snout: You can smell blood a mile away. It circles around the victim, and the circles keep getting narrower and narrower. Turns up his nose... Oh my God! The jaw looks like a trap! She closed her sharp teeth. This is how he hunts... Svetlana Volosevich

There are no gill covers, but on each side there are 5–7 gill slits. There is no swim bladder. Sharks are armed with many sharp teeth in their mouths and have an elongated body with an unequal tail. There are about 370 species of sharks. Gill slits

Sharks are very widespread: they live in coastal and open waters, some in rivers (for example, in the Amazon, Ganges). Most sharks are viviparous, some lay eggs. Almost all sharks are predators. They feed on fish, bottom invertebrates, echinoderms, mollusks, and worms.

Most sharks - great white, blue, blacktip reef, hammerhead and others - swim continuously day and night: firstly, they do not have a swim bladder, and if the shark stops, it will go to the bottom; secondly, sharks, with the exception of some species, do not have a mechanism for pumping water through their gills, from which the blood receives oxygen.

Sharks are the ocean's most mysterious and maligned creatures. Having existed for several hundred million years, they have changed only slightly over the past ten million years. There are about 370 species of these fish, ranging from the 15 cm carnivorous dwarf shark to the 13 m planktivorous whale shark. Dwarf shark Whale shark

WHALE SHARK, feeding on plankton and distributed in the southern parts of the Atlantic, Pacific and Indian oceans. The largest specimen, according to precise measurements carried out by scientists, was 12.65 m in length, 7 m in circumference of the thickest part of the body and weighed 15-21 tons.

Giant shark

Tiger shark

The tiger shark is usually quite slow, but becomes fast and agile when it smells food. Migratory birds, cormorants, sea snakes, pieces of dolphins and crocodiles that fell into the water were also found in the stomachs of tiger sharks. This shark is not unduly squeamish about carrion and garbage. The list of edible and inedible objects extracted from the stomachs of tiger sharks is very long and includes dogs, a cat, a cow's hoof, deer antlers, various rags, boots, bags of coal, tin cans, beer bottles, cigarette boxes, potatoes, leather wallet and many other things. In tropical waters, the tiger shark is perhaps the most dangerous species. There are many known cases where body parts of human victims were found in the stomachs of caught sharks. Some of these finds are probably explained by devouring corpses, but many of the victims undoubtedly met the shark while still alive and well. Attacks have been reported in many areas - off the coast of Florida, the Caribbean islands, Senegal, Australia, etc. These attacks took place both near and far from the coast. Thus, off the coast of New South Wales (Australia) in 1937, a tiger shark killed two young men swimming on the beach; in 1952, near a small island in the Puerto Rico region, a shark attacked an underwater hunter who had harpooned a fish; in 1948, a boat heading to the coast of Florida was attacked. The list of documented tiger shark attacks on people and boats is quite impressive in recent years.

White shark Nurse shark Hammerhead shark Polar shark Herring shark

Stingrays are characterized by a very “flattened” body and large pectoral fins fused to the head. The mouth, nostrils and five pairs of gills are on the flat and usually light-colored underside. The tail is whip-shaped. Most stingrays live in seawater, but there are also several freshwater species. The upper side of stingrays is adapted in color to a particular living space and can vary from light sand to black. On the upper side there are eyes and holes into which water enters for breathing. Most species of stingrays lead a bottom-dwelling lifestyle and feed on shells, crayfish and echinoderms. One of the most famous species of stingrays is the manta ray. Stingrays from the eagle family reach large sizes, whose wingspan can reach 2.5 meters and length - up to five meters; as well as stingrays from the stingray family, reaching 2.1 meters in width and up to 5.5 meters in length. A special “weapon” is endowed with a detachment of electric stingrays, whose representatives, with the help of a special organ made of transformed muscles, can paralyze prey with electrical discharges from 60 to 230 volts and over 30 amperes.

Manta Sea Fox Eagle Stingray Electric Ray

The body of chimeras tapers towards the rear end and ends with a long (up to half the length of the body) whip-like tail. The length of adults from the front end to the tip of the tail varies from 0.6 to 1.5 meters. Large wing-like pectoral fins give chimeras their characteristic appearance. There is an open lateral line groove on the side of the head and body.

Slide 1

Class cartilaginous fish: sharks and rays. Class of bony fish: cartilaginous, lobe-finned, lungfish and ray-finned.

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The purpose of the lesson:
Study the origin and general characteristics of fish. Class cartilaginous fish: sharks and rays. Class of bony fish: cartilaginous, lobe-finned, lungfish and ray-finned.

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Slide 4

Ichthyology is the science of fish.

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Characteristics of the fish superclass:
The body is covered with skin in which scales are embedded (placoid in sharks, bony in bony fishes) Skeleton: skull, gill covers, gill arches, trunk skeleton (spine, ribs) and skeleton of paired limbs. The muscles are differentiated. The nervous system consists of the spinal cord and brain, from which 10 pairs of cranial nerves arise. Well developed sense organs (eyes, hearing, lateral line, sense of smell) Digestive system: oral cavity, pharynx, esophagus, stomach, intestines, anus, liver and underdeveloped pancreas. The hydrostatic apparatus - the swim bladder - is filled with gas, which includes oxygen, nitrogen, and carbon dioxide. Respiratory organs - gill apparatus. The excretory organs are the primary kidneys. One circle of blood circulation. The heart is two-chambered, consists of an atrium and a ventricle. Mostly dioecious (sea bass is hermaphrodite). Fertilization is external.

Slide 6

Comparative characteristics of the main groups of fish.
Group of fish Features of external structure Features of internal structure Number of species Representatives

Slide 7

Sharks. Top row, from left to right: carhariformes (black sawtooth shark), katraniformes (common dogfish, polar shark). Bottom row, from left to right: heterotoothed (Australian bull shark), sawtooth (Southern sawtooth shark), scavatine (European angelfish).

Slide 8

Stingrays. Top row, from left to right: sawfish (common sawfish), diamondback (diamond ray, spotted eaglefish). Bottom row, from left to right: stingrays (giant sea devil (manta), American stingray), electric stingrays (common electric stingray).

Slide 9

Sturgeon. Top row, from left to right: beluga, Siberian sturgeon, sterlet. Bottom row, from left to right: stellate sturgeon, common shovelnose, paddlefish.

Description of the presentation by individual slides:

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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

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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.