See what "snakes" are in other dictionaries. General characteristics of snakes How snakes molt and hibernate

State Institution "KRASNOARMEYSKAYA SOSH PAVLODAR DISTRICT"

research project

"Who are the SNAKE?"

Work completed: Maimakov Aidar

student 4 "B" class

Head: Bychkovskaya E.V.

primary school teacher

year 2013

Table of contents

IINTRODUCTION

IIsnakes

1. The structure of snakes

2. Classification of snakes.

3. Interesting facts from the life of snakes.

4. Snakes of Kazakhstan

5. The most - the most

6. Snakes - truth and fiction.

7. Famous "Snakes" Kazakhstan.

III. Practical part.

The image of snakes in art, culture

"Photoshoot"

Conversation and survey among 4th grade students

IV.Conclusion.

V.Bibliography.

I . Introduction

The topic of my research: "Who are snakes?"Why did I choose the topic "Who are snakes"?I love reading encyclopedias about animals, especially about snakes. I have long been interested in the question: who are snakes and are they dangerous?I have read many books and magazines on this subject.I wonder what the nature of the snake is.Exploring the class of reptiles on the example of snakes, I wanted to know my character, although I was not born in the year of the snake, but 2013 is the year of the black water snake.

GOAL:
Identify the characteristic features of snakes and their relationship with people.

Tasks:

Familiarize yourself with the literature on the topic.

Learn to work with different sources of information.

Learn about the lifestyle of snakes.

Find interesting facts from the life of snakes.

Find out which famous people of Kazakhstan were born in the year of the Snake.

Analyze the information received and draw conclusions.

Examination methods:

Search for information

Analysis and generalization of literature;

Specification (highlighting the main);

Structuring work;

Self-esteem.

II . SNAKE

SNAKE (Serpentes, Ophidia) - a suborder of the class of reptiles. Snakes differ from other reptiles in their elongated body and the absence of paired limbs, the external auditory meatus and movable eyelids.

Each of these features is also found in lizards, from which snakes (presumably) descended in the Cretaceous period (135-65 million years ago), but together they are characteristic only of snakes. Currently, about three thousand species of snakes are known.Among the various varieties of snakes, there are both harmless and poisonous species that are very dangerous for humans and animals. Science is the study of snakes .

II. 1. The structure of snakes.

The body of a snake is divided into head, body and tail. In most cases, the skeleton consists of a skull and a spine (from 141 to 435 vertebrae in some fossil forms), to which the ribs are attached. Only a few species of snakes retain the rudiments of the hind limbs.

Snakes are perfectly adapted to the absorption of large prey, this is expressed in the structure of the skeleton. The right and left halves of the lower jaws are connected movably, the ligaments have a special extensibility. The tops of the teeth are directed backwards: when swallowing food, the snake, as it were, "sits" on it, and the food bolus gradually moves inward. Snakes do not have a sternum, and the ribs end freely. Therefore, the part of the body in which the victim is being digested can be greatly stretched.

Many snakes are venomous. On their upper jaw are large canalic or grooved teeth. The poison produced by the modified salivary glands enters the base of the tooth and flows down the canal or groove to the top. When the snake's mouth is closed, the venomous teeth lie parallel to the palate. When attacking, the mouth opens wide, and the poisonous teeth are directed downward or at a slight angle forward, and the snake plunges them into the victim.

All internal organs of snakes are elongated. The esophagus and stomach have a considerable length, the intestines are relatively short. The left lung is usually underdeveloped or atrophies, and the back of the right lung becomes a thin-walled air reservoir. Some snakes have a sac-like extension at the back of the trachea - the tracheal lung. The bladder is missing.

The eyes of snakes are covered with a transparent cornea formed by fused eyelids. In diurnal snakes, the pupil is round or in the form of a transverse slit, in nocturnal snakes it is vertical. Vision, like hearing, is not the main sense organ of the snake and is less developed than in lizards. When attacking prey, the snake can miss, especially often this happens during molting, when the surface layer of the eyelids is separated along with the skin and the eyes become cloudy. Due to the reduction of the middle ear and eardrum, snakes can only distinguish loud sounds that are accompanied by shaking of air or soil.

The main sense organ of the snake is a long tongue forked at the end. When the mouth is closed, the tongue protrudes through the semicircular notch of the upper jaw, and during swallowing food is removed into a special muscular vagina. With the help of the tongue, the snake feels the surrounding objects, the molecules of odorous substances that fall on the tongue are transferred to the paired organ of smell - Jacobson's organ. Focusing on the smell, the snake can move and look for the victim in complete darkness. In addition, the tongue can serve as a temperature sensor. The same function is performed by special organs located on the head of some snakes (python, African viper, pit snake).

The snake's brain is relatively small, but the spinal cord is well developed, therefore, despite the primitiveness of reactions, snakes are distinguished by good coordination of movements, their swiftness and accuracy.

The surface layer of the skin forms scutes and scales in the form of elongated plates arranged in a tile-like manner, often longitudinal elevations are visible on them - ribs. They play a big role in the movement of snakes living among rocks or on trees: due to the roughness of the covers, the snake can cling to the bumps of stones or bark. On the contrary, the species that live among thickets of grass and shrubs are devoid of protrusions of scales, which in this case will only slow down movement.

The large head shields are usually irregular in shape; abdominal - hexagonal. They are located in one row, the last - anal - the abdominal shield is divided into two. Wriggling, the snake with the help of abdominal shields is repelled from the surface on which it crawls, and moves forward. In addition, they protect internal organs. Sea snakes do not have such problems, and they lack ventral scutes. Undertail shields can lie in one (slender boa, lizard snake) or two rows (common viper, Amur snake).

When food is swallowed, the scutes and scales move apart, exposing previously hidden folds of skin. The scales are firmly interconnected in longitudinal rows, but each row can be shifted laterally relative to the neighboring ones. The abdominal shields, on the contrary, diverge in the longitudinal direction. At the same time, the body of the snake lengthens.

Shedding occurs up to several times a year. Old skin begins to flake off in the lip area, wraps up and gradually disappears. On the "creep out" a transparent cornea of ​​\u200b\u200bthe eyes is noticeable.

The color of the skin can change during life with molting. Coloration also depends on the sex and individual characteristics of the snake and in most cases performs a camouflage function.

II . 2. Classification of snakes.

The suborder Snakes is divided into 8–16 families. Main families:

Slepuns (Typhlopidae ). Small snakes with a worm-like body. They are adapted to underground life: the head is covered with large shields, the bones of the skull are tightly fused, the short tail serves as a body support when the animal moves in the thickness of the ground. The eyes are almost completely reduced. The rudiments of the pelvic bones were found in the blind rats. The family includes about 170 species, most of them live in tropical and subtropical regions.

False-footed (Boidae ) got their name for the presence of rudiments of the hind limbs, which turned into claws on the sides of the anus. The pseudo-legs include the anaconda and the reticulated python - the largest modern snakes (they can reach 10 m in length). Three subfamilies (Boas, Pythons and Sandboas) include about 80 species. They live in the tropics and subtropics, some species live in the arid regions of Central Asia.

To the aspid snakes (Elapidae ) includes more than 170 species, including cobras and mambas. A characteristic feature of aspids is the absence of a zygomatic shield. The body is elongated, the tail is short, the head is covered with large shields of regular shape. Representatives of the family lead a terrestrial lifestyle and are distributed mainly in Africa and Australia.

Most sea snakes (Hydrophiidae ) never go to land, they are adapted to life in water: voluminous lungs, valves that close the nostrils, a streamlined body and an oar-shaped tail. Very poisonous. The family includes about 50 species living in the Indian and Pacific Oceans.

Vipers (Viperidae ) have a thick body with a flat triangular head, a vertical pupil, well-developed poisonous glands and a tracheal lung. The subfamily of the Pitheads includes the muzzle and rattlesnakes, the real vipers include vipers, gyurza and sand efa. In total, the family includes about 120 species of snakes.

already shaped (Colybridae ) is a family that includes about 70% of modern snakes (about 1500 species). Snakes are ubiquitous; they are adapted to life in the forest floor, burrows, trees, semi-deserts or water bodies. Differ in a variety of food preferences and modes of movement. The family as a whole is characterized by the absence of the left lung, mobile tubular teeth and rudiments of the hind limbs, as well as the horizontal position of the upper jaw. According to the structural features of the teeth and scaly cover, several subfamilies are distinguished.

II . 3. Interesting facts from the life of snakes.

All snakes are predators, many of them can capture prey that is much larger than the snake itself. Usually small and young snakes feed on worms, molluscs, insects, some amphibians, reptiles, birds, fish, rodents and larger mammals. It can take several months between two meals.

In most cases, snakes lie motionless, lying in wait for prey, and then rush at it with amazing speed and immediately begin to swallow. Poisonous snakes bite and wait for the poison to work, and boas wrap around the victim and strangle her.

There are several ways to move snakes. Usually the snake bends in a zigzag manner and is repelled by parts of the body adjacent to the ground. In the desert, snakes use the so-called “lateral move”: the body touches the surface only at two points, the front part of the body is transferred to the side (in the direction of movement), then the back is “pulled up”, etc. The "accordion" mode of movement is different in that the snake's body is gathered into tight loops, and the front of the body moves forward. Large snakes move in a straight line "caterpillar", clinging to the soil with shields and straining the muscles of the abdominal part of the body.

Snakes are ubiquitous, with the exception of New Zealand and small oceanic islands. They have mastered life in the forest, steppe, desert, underground and even in the sea. The greatest number of species lives in the warm countries of East Asia and Africa; over 50% of Australia's snakes are venomous.

Some snakes, under favorable conditions, can bring offspring up to several times per season, others do not breed every year (for example, the Caucasian viper). Bamboo keffiyeh, found in India and Pakistan, can breed all year round. Like most animals, snakes have their own "marriage rituals" of varying degrees of complexity. After mating, the females are able to keep the partner's sperm in an active state for quite a long time and do not need to meet the male again for a new fertilization.

Usually cubs hatch from eggs, but live birth is also widespread (typical for sea snakes, boas, vipers). The female develops a placenta through which the embryos receive oxygen, water and nutrients. Sometimes the female does not have time to lay her eggs, and the young hatch inside her genital tract. Such a case is called ovoviviparity (vipers, muzzles).

In one clutch there are an average of 10 eggs. Embryonic development is temperature dependent, so snakes make sure the nest is warm and the eggs don't dry out.

Snakes usually live 5–10 years, some individuals live up to 30–40 years.

Many birds and mammals feed on snakes (storks, eagles, crows, hedgehogs, representatives of the Carnivorous order and even pigs), and even other snakes.

II . 4. Snakes of Kazakhstan

More than 18 species of snakes live on the territory of Kazakhstan. Each species of reptile has its own beauty and ecological value.

For a person, only four types of snakes can be dangerous, two types - vipers, a steppe viper and an ordinary one, one type of muzzle and viper, or a Lebanese viper.

The common viper lives in the north of the republic and in Altai. The steppe viper is distributed throughout the territory of Kazakhstan, with the exception of waterless deserts. Cottonmouths live in deserts, in mountains, along the banks of rivers and lakes. Gyurza is found in the south of Kazakhstan, almost on the border. The remaining types of snakes belong to the families - boas and snakes. Two species belong to the family of boas - oriental and sand boas. The most numerous are representatives of the family of already-shaped, which include snakes, snakes, copperhead and arrow-snake, a total of fourteen species.NOT dangerous for a person.

Four types of snakes are listed in Kazakhstan

• red-striped snake found in the South Kazakhstan region

  striped snake found in the Zaisan basin

  Four-stripe snake

II . 5. The most-most ...

The longest snakes

The Giant Snake is a South American anaconda boa constrictor, one of the longest modern land vertebrates. The anaconda caught in Colombia reached the longest length - 11.43 m

The longest venomous snake

The largest poisonous snake is the king cobra, which lives in India, Indochina, South China, on the Mallaka Peninsula. They can reach 5.5 m in length. These poisonous giants are very dangerous for both animals and humans. From the bite of a king cobra, a person dies in a few minutes, its poison is so strong.

The smallest snake

The smallest snake on Earth is a blind snake that lives on the island

Nosy Be, near Madagascar. Its length reaches only 10 cm.

The heaviest snake

The fastest venomous snake

The fastest snake in the world is the mamba. (11km/h)! And in the branches it is even faster. It is difficult for a person to escape from it. It is the most venomous snake on the African continent. You can meet her here not only in the forests and in the field, but also in villages and even in houses. A person dies from her bite (if emergency measures are not taken) within half an hour. No other snake in Africa is more feared than mambas.

The oldest snake

A boa constrictor named Popeye, who died at the Philadelphia Zoo in 1977, lived to be 40 years 3 months and 14 days old.

The thinnest European snake

The thinnest European snake is the olive snake.

The most venomous snake in Kazakhstan is the gyurza.

The thinnest snake

Common belt snake. Her body at a length of 2 meters thick with a pencil.

The longest fast

A case is known when an adult anaconda in a zoo refused to eat for 500 days. In a special experiment, a habu viper snake lived without food for three years and three months.

Without a drop of water

Snakes are able to do without water for a long time. For example, in one of the experiments, a naturally moisture-loving king cobra lived without a drop of water for five years.

The most accurate snake

The ringal snake, which lives in India and South Africa, is considered the most accurate in attacking prey. It is capable, for example, from a distance of 5 m to throw out a deadly stream of poison directly into the eyes of an approaching person or animal.

The most "northern" snake

Reptiles, or reptiles, have all the necessary adaptations for terrestrial existence. They are found even beyond the Arctic Circle, but rarely and only 2 species - an ordinary viper and a viviparous lizard. However, their distribution beyond the Arctic Circle is very limited, but in some places they enter the Arctic (no more than 0.5 °).

II . 6. Snakes: truth and fiction.

There are endless legends, fairy tales, myths, all kinds of terrible stories about snakes. It is perhaps difficult to find a group of wild animals to which people would be more prejudiced than these, even in our enlightened age.

Here is a paradox: all over the world people are afraid of snakes, but at the same time, since ancient times, they deify, worship and use their "gifts" for healing. Taking a medicine made with the use of snake venom, the patient is full of hope for relief, but, having become healthy again and having met a living snake, he runs in a panic or, on the contrary, tries to kill an innocent animal.

For many people, the mere mention of snakes causes disgust and sharply reduces appetite. And others, on the contrary. In Bangkok, the capital of Thailand, in a first-class restaurant you can order python steak or cobra with white sauce! Recently, in one of the cities of Malaysia, a conflict arose between doctors and traders of live snakes, who sell reptiles to restaurants for cooking gourmet dishes. Doctors rightly defended snakes, especially cobras, from the poison of which drugs are made.

People who have had to try various dishes made from snake meat say that if they did not know what the dishes were prepared from, they could mistake them for fish or game.

Different peoples of the earth have different attitudes towards snakes. Among the inhabitants of Europe and North America, snakes are not held in high esteem, they are always considered vicious, insidious and harmful animals. And in India, at the same time, snake festivals are held annually "nagpanchami". There is in this country a city called Nagpur, the Naga mountains, the Nagari river: in all these names the root is "nag" ("serpent deity").

In ancient times, the cult of the snake was widespread in the world. She was worshiped by the Romans, the inhabitants of Crete, the Indians of America ... Many African peoples built special temples for keeping snakes and addressed them with the words: "You, my lord!"

It turns out a paradox: people are chasing snakes in many countries, and at the same time, in the same countries, a snake is depicted on the medical emblem - and, no doubt, poisonous! There are different versions of the emblem: a bowl wrapped around by one or two snakes, a rod wrapped around a snake or a pair of these animals.

The history of such a seemingly strange emblem is connected with Greek and Roman mythology. The Greek god of healing Asclepius (among the Romans he is Aesculapius) has long been depicted with a staff entwined with a snake. One of the legends says that snakes allegedly know the healing properties of various plants. To gain this knowledge, you need to turn into a snake. Asclepius succeeded in this, who, regaining the appearance of a man, used herbs in healing. According to another legend, the god of healing in his "practice" used the healing properties of snake venom. Today, the venom of many species of venomous snakes is widely used in medicine. Preparations made from it help patients with epilepsy, angina pectoris, hemophilia, rheumatism, sciatica and other ailments.

Poison is also used to make serums to help people and animals affected by the bites of poisonous snakes.

Is this a big problem?

According to the World Health Organization, about 500,000 people are bitten by venomous snakes worldwide every year. Of these, 30-40 thousand die. Most cases occur in Asia, Africa and Latin America. Complicating the situation is the fact that the network of medical institutions in many developing countries is still poorly developed, witchcraft has not been eliminated, and many people die because, instead of providing timely assistance, healers demonstrate their “remedies”, refuted by science.

Snakes are very popular: legends tell about them, cartoons are shot. Snakes attract attention with their mysteriousness.

II . 6. Famous people of Kazakhstan born in the year of the Snake

Opens the star hit parade of representatives of the year of the SnakeKarim MASIMOV (born in 1965) , who recently replaced the post of Prime Minister of the country with the chair of the head of the Presidential Administration. By the way, a specialist in international law, an economist who speaks five languages ​​and has three children, Karim Kazhimkanovich began to quickly move up the career ladder precisely in the year of the Snake - in 2001 he first became Deputy Prime Minister.

No wonder the Snake is considered a symbol of wisdom and knowledge. Another representative of the upcoming astrological year of the Snake in our government is the Minister of Education and ScienceBakytzhan ZHUMAGULOV .

Gulshara Abdykalikova, Advisor to the President.

The most famous “snake” in the Pavlodar region is Alexander VERBNYAK, Akim of Ekibastuz.

III . Practical part.

III . 1. The image of snakes in art, culture

The serpent is an image of world folklore that has received numerous variations at different stages of cultural development and in different national traditions. The serpent is a popular character in fairy tales and epics, most often an enemy with whom the hero will have to enter into an uncompromising struggle. In Russian fairy tales, a snake is a multi-headed creature that can fly, spewing fire.

One of the most striking images of a snake in Russian literature belongs to the tales of Pavel Petrovich Bazhov.

The image of a snake is used in heraldry, culture and art.

In children's films and cartoons, we also meet snakes.

III . 2. "Photo shoot" with a python

I managed to keep real pythons more than once (literally on my neck). They are quite heavy and a bit slippery. I have always been in awe of these snakes, feeling their power. The strength of the python is great, and if he takes your neck for a tree trunk and grabs you harder than you expect, you will have a hard time. Therefore, with such a snake, you need to be extremely careful and vigilant, do not make sudden movements and do not forget that the python is a wild, unpredictable animal, subordinate to its natural instincts.

Perhaps you will refuse to ever take a python in your hands, knowing that you can get scabies or mites as a gift from a snake.

In addition to such dangers, there is currently the so-called "snake therapy". Non-venomous snakes massage people. They crawl along the back, relieving feelings of fatigue and pain.

However, not all people are able to call such a massage "relaxing".

Many people keep pythons as pets. And to the ironic question of acquaintances: “How is your bastard?”, They answer quite sincerely and confidently: “He is not a bastard, he is a friend.”

Probably, precisely because the python is a peaceful, calm creature, there are many who want to be photographed with him. It is not for nothing that at the present time, a time of stress and tension, psychologists love the expression “python calmness” so much.

III . 3. Poll among 4th grade students.

I decided to reveal the level of knowledge of third-graders about representatives of the order of reptiles - snakes. To do this, I conducted a survey in which 15 schoolchildren took part. Each student was asked 7 questions to which they had to answer.

1. Are you afraid of snakes? If yes, then why?

2. Are all snakes poisonous?

3. What do snakes bite?

4. What is the use of snakes?

5. What do you know about snakes?

6. What kind of people are called "snakes"?

7. What cartoons or feature films about snakes did you watch?

The results of the survey showed that 60% of students are afraid of snakes, considering these reptiles as dangerous enemies due to the presence of poison in their body. 40% are not afraid of snakes, assuring that among their representatives there are harmless individuals, for example, snakes.

96% of schoolchildren know that not all snakes are poisonous.

72% of students correctly claim that these reptiles bite with their teeth, 10% believe that with their tongue, 18% do not know.

Indeed, snakes have two poisonous teeth on the upper jaw, one on each side. When the snake bites, the muscle presses on the gland, squeezing the poison into the teeth, which enters the victim's body through the grooves of the teeth.There is also the so-called spitting cobra, which can shoot venom from its poisonous teeth. A cobra aims at the eyes of an animal that threatens it, such as an antelope or a buffalo. The spit reaches its target at a distance of up to two meters and causes blindness almost instantly.

44% of students wrote that the value of a snake is in its venom, since medicines are made from it; 8% know that snakes kill rodents; 28% - cannot explain what is the use of this order of reptiles; Unfortunately, 20% of schoolchildren see the value of snakes only in the skin obtained from them.

Answers to the question: "Which people are called "snakes"?" turned out to be addicted to a prejudiced, misunderstanding and unfair attitude towards snakes.

32% of students answered that "snakes" are called evil people, 4% - insidious, 4% - cunning, 4% - bad, 4% - mutants, 4% - nasty, 4% - dishonorable, 4% - spoiled, 12% - people with a flexible, plastic body, 28% - found it difficult to answer.

As it turned out, schoolchildren were able to remember only one film each (maximum two each), where it would be about snakes, 16% did not write anything.

So, the guys named such films: "Animal World", "Zoo", "How to Treat a Boa Constrictor", "Mowgli", "Snake Catcher", "Harry Potter and the Chamber of Secrets", "Kung Fu Panda".

The survey showed that the majority of third-graders have superficial knowledge about representatives of the order of reptiles - snakes.

IV . Conclusion.

Thus, in my work, using literary, Internet sources, I learned a lot of interesting things about mysterious and terrible creatures, about snakes, about which many tales were told.

Hence the conclusion

Snakes are wise, careful.

Snakes are patient.

Snakes are hardy.

Need snakes.

The snakes are very different.

The external calmness of snakes is deceptive.

I love learning new things. My favorite subject at school is knowledge of the world.

It was very interesting to do research work.

I learned that any profession related to creativity is suitable for the Snake.

He has a bright and eventful life.

People - the Serpent have a lot of energy, but the Serpent spends it not continuously, but in portions.

The calm and poise of the Serpent is deceptive.

BIBLIOGRAPHY

Akimushkin I.I. Whims of nature. - M .: Thought, 1981. Ch. "South of the Sahara", "Anaconda", "Sixth, Seventh and Other Senses".

Sladkov N.I. Reptiles. - M .: Children's literature, 1988.

What. Who it. V.2.- 4th edition.-M.: Pedagogy - Press, 1999.

Bram A.E. Life of animals. T.3: Reptiles. Amphibians. Fish. Invertebrates.- M.: TERRA,2012 G.

http://zveri.on.ufanet.ru/zmei.html

Current page: 7 (the book has a total of 18 pages) [accessible reading excerpt: 12 pages]

Font:

100% +

23. Class Bony fish. Orders: sturgeon, herring, salmon, carp, perch

1. How do bony fish differ from cartilaginous ones?

2. Why are bone groups more numerous than cartilaginous ones?

3. What do all bony fish have in common?

Features of the external and internal structure, biology and ecology make it possible to distinguish some systematic groups among the diversity of fish. The most significant of them are the following.

Squad Sturgeon, or osteocartilaginous,- a small group of fish (Fig. 91). In the structure of sturgeons, ancient features have been preserved, emphasizing their resemblance to cartilaginous fish. Throughout life, sturgeons retain a notochord, an osseous-cartilaginous skeleton. The body is elongated, the head begins with a flattened snout, on the lower side of which there are two pairs of antennae and a mouth in the form of a transverse semilunar slit. The jaws are devoid of teeth. In the skin layer on the sides along the body and on the ridge there are five rows of large bone plaques, small bone plates are randomly scattered between them. The pectoral and ventral fins are attached horizontally to the body. The caudal fin is unequal, reminiscent of a shark's tail. There is a swim bladder.

Family members sturgeons are found mainly in the northern hemisphere of temperate latitudes of Europe, northern Asia and North America. As an adult, these fish spend most of their lives in the seas. Baikal sturgeon, American lake sturgeon and sterlet are considered freshwater fish. In spring or autumn, sturgeon for breeding come from the seas into the rivers: Volga, Don, Ural, Ob, Yenisei, Lena, etc. Individuals that entered the rivers in autumn overwinter in them and spawn the next year in the spring, simultaneously with the newly approached. Hatched larvae, growing sturgeon fry with the current of water are gradually carried to the mouth of the rivers, and then to the seas.

Rice. 91. Sturgeons

Sturgeons feed on mollusks, worms, crustaceans, larvae of aquatic insects, mainly mosquitoes. Far Eastern Kaluga and European Beluga are predators. They feed on small and large fish. At autopsy, a large number of herring, roach, chum salmon and even ducks were found in their stomachs.

Sturgeon meat is valued for its excellent taste. It is eaten fresh, salted, smoked. Sturgeon caviar is a very valuable nutritious product.

Rice. 92. Herring

Sturgeons are caught in Russia, Iran, the USA, France, Spain and a number of other countries. The Russians catch them mainly in the Caspian and Azov Seas, the rivers of Siberia and the Far East.

Sturgeons have always been poached. And the deterioration of the ecological state of many rivers, the construction of hydroelectric dams on them led to the extinction of fish. Hydroelectric power plants cause especially great damage to the sturgeon population, since only a few individuals through bypass channels and through fish elevators get above the dam.

Order Herring. The fish of this order have an elongated body, slightly compressed laterally (Fig. 92). The color of the back is dark blue or greenish, the belly is white with a silver tint. Paired and unpaired fins are soft. The lateral line is not visible. The body length is usually 5–75 cm, sometimes reaching 5 m.

Most of the herring species live in the seas, there are also anadromous ones - moving for reproduction from the seas to the rivers and vice versa. Few representatives of the detachment live in fresh water. They feed on planktonic invertebrates. Large individuals, as a rule, are predators that eat small fish.

Rice. 93. Salmon

The order consists of three families. The most famous fish from the family herring, relatively small or medium in size, usually 35–45 cm long, less often more. Herring live mainly in the seas. Commercial value have oceanic (Atlantic, Baltic, White Sea, Pacific) herring, sardine, willow. The smallest fish of commercial importance are sprat and tyulka, living in the Baltic, Black and Caspian Seas.

Order Salmonformes. This includes fish that look like herring-like fish, from 2.5 cm to 1.5 m long (Fig. 93). They live in the seas, feed, grow, reach sexual maturity, but enter rivers for reproduction. Chum salmon, pink salmon, sockeye salmon and others from the salmon family spawn in the rivers of the Far East; salmon, trout- in the rivers of the European North; chinook salmon- usually in the rivers of Alaska. All salmon are commercial fish, highly valued for their tasty meat and caviar. No less valuable are freshwater: trout, Baikal omul, Chud whitefish, vendace. Many of the salmon are bred in special fish farms.

Rice. 94. Cypriniformes

Order Cyprinidae. Representatives of the order (Fig. 94) are in many ways similar to the herring-like ones, but differ from them in some anatomical features. The number of species in the order is about 15% of all bony fish.

Among cyprinids there are herbivores, carnivores and omnivores. There are several types of predatory fish piranha, living in the rivers of South America. Dangerous for the life of animals and humans are common piranha, up to 30 cm long, and eastern brazilian big piranha, 60 cm long. All piranhas have sharp teeth that allow them to tear pieces of meat from the body of a victim that has fallen into the water.

Rice. 95. Perciformes

Predatory fish include electric eel. The body length of the fish is 1–1.5 m, sometimes more. The skin is bare, there are no scales. Eel lives in water bodies with a minimum oxygen content in the water. In the process of evolution, eels have developed the ability to absorb oxygen from the air: for this, the eel rises to the surface of the water several times within an hour and captures air with its mouth.

Electric eel has developed electrical organs. They are comparable to electric batteries located on the sides of the body from head to tail and giving an average voltage of 350 V at a current strength of 3 / 4 A. Electric organs serve as protection against enemies and for obtaining food. The electric field at the moment of discharge spreads in a diameter of 5–10 m from the eel. Animals that fall into the field of action of the discharge are paralyzed and become the prey of an electric eel.

In the water bodies of Russia, the most common representatives of cyprinids are roach, dace, asp, tench, barbel, bream, fish, bleak, sabrefish, carp, crucian carp, grass carp, all are of great commercial importance. A number of species are artificially bred in pond farms. In recent years, in most countries, including Russia, they began to breed such herbivorous fish as cupid, silver carp and their hybrids: labeo, barbels, catleys, cirrhines. Some tropical cyprinids with beautiful bright colors have become objects of keeping in aquariums. Over the years, breeders have bred colorful, varied goldfish from silver carp.

The order Perciformes is the most numerous group of fish in terms of species composition (Fig. 95). They are distributed in water bodies of all continents and in the oceans. A characteristic feature of the perciformes is the presence of two dorsal fins with sharp spines. Some of them have no swim bladder. Body length from 1 cm to 5 m and weight from less than a gram to 1000 kg or more. For example, moon fish it can be up to 3 m long and weighing up to 1400 kg. The most common families are: rock perches; perch with childbirth zander, perch, ruff; scad; sea ​​carp; notothenic; catfish; goby; sailboats. Almost all fish of the perch-like order are edible and are objects of trade, as well as amateur fishing. Small fish of this group perfectly live and breed in aquariums.

From modern lungfish known: protopteres from Africa, lepidosirenus, or flake, from South America, neoceratodes, or cattail, from northeast Australia (Fig. 96). Regardless of geographical location, all lungfish live in shallow, slow-flowing rivers, marshy lowlands, densely overgrown with vegetation.

Rice. 96. Lungfish

Rice. 97. Coelacanth coelacanth fish

Such reservoirs dry up during the year during the drought period and are filled with water for several months during the rains. Fish are considered ancient and are characterized by a primitive organization. They are well adapted to life in waters with a low oxygen content, and in the absence of water they can switch to pulmonary respiration.

About 400 million years ago, in the seas and fresh waters of our planet, lobe-finned fish(Fig. 97). They were represented by a large group of primitive bone fish. Until recently, it was believed that representatives of the Loop-finned fish became extinct about 7 million years ago. In 1938, off the southern coast of Africa, in the Indian Ocean, the first specimen of an unknown fish was caught from a depth of 70 m. Ichthyologist L. B. Smith, who first described a living "fossil" lobe-finned fish, called it coelacanth. The second specimen of the lobe-finned fish was caught with a line from a depth of 15 m in the same area. By 1980, more than 70 coelacanths had been caught.

Coelacanths reproduce by live birth. Like their distant ancestors, coelacanths have skeletal formations in paired limbs, equipped with powerful muscles. These fish have no practical commercial value.

Bony fish: Sturgeon, Herring, Salmon, Carp, Perch.

Questions

1. What biological features allowed fish to populate almost all the water bodies of the planet?

2. What species of sturgeons were distributed before or live now in the water bodies of your area?

3. What are the similarities between sharks and sturgeons?

4. What are the main differences between sturgeons and sharks?

5. What are the structural features of the living "fossil" coelacanth fish coelacanth?

6. What kind of fish is used in the fight against malaria? What is this type of struggle called?

7. What bony fish are protected in your area?

8. Why are aquarium fish attractive to keep?

Do you know that…

The largest of the sturgeons are the Far Eastern kaluga from the Amur basin and the European beluga living in the Caspian, Black, Azov and Adriatic seas, up to 4 or more in length and weighing up to 1000 kg. Commercial forms weighing 70–80 kg. Females spawn more than 9 thousand eggs. The life expectancy of these fish is over 100 years.

The smallest representative of sturgeons is pseudoshovelnose, living in the basins of the Amudarya and Syrdarya rivers, weighing less than 1 kg.

24. Class Amphibians, or Amphibians. Squads: legless, tailed, tailless

1. Why did the animals of this class get the names of amphibians, legless, tailed, tailless?

2. What types of amphibians are found in your area?

General characteristics. Class amphibians, or amphibian, includes animals adapted to life both on land and in water (Fig. 98). On land, most of them are found in the adult state, and the reproduction, growth and development of tadpole larvae takes place in the aquatic environment. Amphibians appeared about 350 million years ago, apparently from ancient lobe-finned fish. They were the first terrestrial vertebrates. They moved on land with the help of paired limbs, breathed with the help of lungs and skin.

The body of modern amphibians is divided into the head, trunk and limbs. On the head are a pair of nostrils for breathing atmospheric air, a pair of eyes protected by eyelids. The skin is naked (frogs, tree frogs), moist from the mucus secreted by special glands (a necessary condition for skin respiration), cool due to constant evaporation of moisture from its surface, keratinized (toads). They breathe air oxygen through the lungs, as well as oxygen dissolved in water through the skin. There are representatives with external gills (see Fig. 102). Blood flows through two circles of blood circulation. The heart of adult amphibians is three-chambered.

Rice. 98. Amphibians

The body temperature is unstable and depends on the ambient temperature, so all amphibians are active only in the warm season of the day and year. When the ambient temperature drops, they fall into a stupor. Animals are dioecious. Fertilization is internal or external. The eggs laid by the female develop in water. The larvae emerging from the eggs do not resemble adult amphibians (Fig. 99) and are similar to fish larvae. They breathe with external gills. The heart of the larvae, like that of fish, is two-chambered. One circle of blood circulation. There is a side line. Movement in water is carried out due to the bends of the tail flattened from the sides. After 2–3 months, the tadpole larva turns into an adult animal.

Amphibians destroy a large number of insects, including blood-sucking ones, and their larvae. They serve as food for many animals and even humans. The frog is an indispensable object of laboratory research. Many species are rare and protected.

Rice. 99. Amphibian larvae

Amphibians are the smallest class of vertebrates. About 4 thousand species are known. All species are grouped into three orders: Legless, Tailed and Tailless.

Squad Legless(Fig. 100) consists of one family worm. The homeland of legless amphibians is the tropical part of Africa, South America and South Asia, the islands of the Indian and Pacific Oceans. Except for the South American caecilians, who live permanently in the water, all other members of the family are underground inhabitants and are found in moist soil at a depth of 30–60 cm.

Rice. 100. Legless amphibians

Rice. 101. Tailed amphibians

These amphibians have a worm-like, cylindrical body, slightly flattened in the dorsal-ventral direction. The skin is naked, abundantly supplied with numerous mucous poisonous glands. From above, the body is divided into many transverse rings, in appearance resembling segments of earthworms. Worms do not have limbs and a tail, their head is small, imperceptibly passing into the body, there are no organs of vision and hearing. Looking for food, worms, like earthworms, make passages in the ground. They feed on invertebrates: worms, snails, larvae and adult insects. They can even attack small snakes. Food is found with the help of well-developed organs of smell and touch.

Squad Tailed(Fig. 101) unites amphibians living north of the equator, in the temperate zone of the Eastern and Western hemispheres. South of the equator, in South America, there is only a small group salamander. The elongated spindle-shaped body of tailed amphibians imperceptibly passes into a long tail, rounded in salamanders and ambist, laterally compressed newts, proteas, axolotls. Curving the tail to the right and left helps these amphibians move in the water. On land, representatives of the caudate move with the help of two pairs of underdeveloped limbs. The fingers at the ends of the limbs of many species are equipped with an easily extensible leathery membrane and are devoid of claws. North American sirens do not have hind limbs.

Rice. 102. Representative of tailed amphibians - striped siren

Breathing in adult tailed amphibians is provided by the lungs, skin and mucous membrane of the oral cavity. Representatives of the detachment constantly living in water breathe with the help of both lungs and external gills. The gills look like feathery branches located on the sides of the head (Fig. 102).

Fertilization is internal and external. Females lay from 2–5 to 600–700 eggs (eggs) in water or in damp places. Egg development lasts 2-3 months. The emerging larvae are similar in appearance and mode of movement to fish larvae.

Detachment Tailless- the most numerous group of amphibians, numbering about 3 thousand species. They are distributed throughout the globe, found on all continents and islands of both hemispheres, with the exception of Antarctica and the northernmost islands. Of the order of tailless amphibians, the most famous are frogs, toads, tree frogs, toads, spadefoot(Fig. 103). Unlike representatives of other orders, the tailless have mastered the land to a greater extent, but have not lost contact with water. These amphibians have a number of specific adaptations to living conditions.

The body is short, squat. The head is wide, without a neck, merged with the body. There is no tail. The skin is naked, equipped with many glands, the secret of which abundantly moisturizes the surface of the body. The head has a pair of movable eyes with nictitating membranes and a pair of nostrils at the tip of the muzzle. They breathe atmospheric air with the help of the lungs and through the skin. The translational movement in the water is intermittent due to the work of long limbs equipped with swimming membranes, turned into flippers. The forelimbs are shorter than the hind limbs, when swimming they are pressed against the body. On the ground, tailless amphibians prefer to move by jumping, using powerful hind limbs. These animals are active throughout the day. Adults lead a predatory lifestyle.

Rice. 103. Tailless amphibians

Tailless amphibians feed on spiders, ants, crustaceans, earthworms, terrestrial and aquatic mollusks and insects. Food is actively searched for with the help of vision in water and on land. They catch flying insects. Small teeth and a sticky tongue, which is attached at the base of the mouth with its front end and is doubled in the oral cavity, help amphibians to grasp and hold prey. At the moment of approaching prey, it is thrown far ahead (Fig. 104).

Tailless amphibians breed in water. The females lay eggs, while the males produce milk. Fertilization of eggs is external. The tadpoles emerging from the eggs are similar to fish and feed on unicellular blue-green algae and protozoa during the first days of life. After 50–60 days in warm water and 80–85 days in cold water, the tadpole turns into a small frog that is able to leave the reservoir and go to land.

Of the real frogs, the most common lake and pond, whose life is mostly associated with water. herbal and moored frogs, on the contrary, use water mainly during the breeding season. In summer, in search of food, they leave the reservoir and live on land.

Amphibians: Legless, Tailed, Tailless. Tadpole.

Rice. 104. Tongue of a frog at the moment of catching an insect

Questions

1. What are the similarities and differences between amphibians and fish?

2. What is the importance of amphibians in nature?

3. What features allow amphibians to live both on land and in water?

4. What is the difference between development and transformation in amphibians and insects?

Tasks

Using various sources of information, list the amphibians that are protected in your area.

Do you know that…

Toads are associated with water only during the breeding season. The surface of the skin of toads is keratinized, so the evaporation of moisture through the skin does not occur. Breathing is carried out to a greater extent with the help of the lungs, which allows the toads to go far from the reservoir. In our latitudes, common and green toads are predominantly common.

25. Class Reptiles, or Reptiles. Squamous order

1. Why are these animals called reptiles?

2. Which of them live in your area?

General characteristics. Most representatives of the class of reptiles are terrestrial animals. The skin is dry, externally covered with horny scales, scutes. Skin glands are usually absent. Reptiles breathe with the help of lungs that have a cellular structure. The heart is three-chambered, consists of a ventricle and two atria. Crocodiles have four chambers. Two circles of blood circulation. The brain has a more complex structure than that of amphibians. The excretory organs are the kidneys. The body temperature is unstable, and therefore the activity of these animals depends on the ambient temperature. Reptiles have separate sexes. Fertilization is internal. Most representatives of this class reproduce by laying fertilized eggs covered with a leathery shell (for lizards and snakes) or calcareous shells (for crocodiles and turtles), but there are also viviparous.

Most reptiles are carnivores or insectivores, while terrestrial turtles feed primarily on plants. Modern reptiles descended from ancient reptiles - cotylosaurs, who lived about 285 million years ago, which still retained in their structure the features characteristic of the oldest tailed amphibians - stegocephalians. The time from 70 to 255 million years ago is considered the era of prosperity and diversity of reptiles. Lived on dry land dinosaurs, floating dominated the water ichthyosaurs, in the air - flying pterosaurs(Fig. 105).

About 100 million years ago, a global drop in temperature occurred on our planet and a prolonged cooling set in. This dramatically changed the environmental conditions and led to the mass death of reptiles. There are about 7 thousand species of modern reptiles, united in 4 orders: Scaly, Turtles, Crocodiles, Beakheads.

Order Scaly (Fig. 106) - the most diverse and numerous in terms of the number of species. It includes lizards, agamas, geckos, monitor lizards, chameleons and snakes. Animals of this order are widely distributed on the continents and islands. Found in all parts of the world.

Rice. 105. Extinct ancient reptiles

Lizards. The body of lizards is elongated, slightly compressed laterally. It consists of a head, a body, two pairs of movable, tenacious limbs with claws and a long tail. Yellowbelly and spindle They have no limbs and are similar in appearance to snakes. The skin of lizards is covered on top with keratinized scales, spikes, shields or ridges that protect them from mechanical damage and moisture loss. The head is movably connected to the body. The eyes are equipped with movable eyelids and a nictitating membrane.

Rice. 106. Scaled reptiles

Lizards distinguish objects well at a distance of several tens of centimeters, but at the time of hunting they react only to moving prey. They hear well. Small teeth are located on firmly connected jaws. The forked tip of the tongue performs the functions of smell, touch, and taste.

Of the lizards that have limbs, the most common quick, viviparous, green, from the legless - the yellow-bellied and the spindle.

In the spring, after the winter awakening, the lizards breed, laying from 6 to 16 eggs in specially prepared small depressions, well lit by the sun. After 50–60 days, small lizards hatch from the eggs. They feed on a variety of insects and their larvae, earthworms, and land mollusks. The viviparous lizard, in contrast to the lizard, prefers damp areas of swamps (more often peat bogs), wet areas of forests. She is not picky about temperature, which allows her to live in the northern regions, almost at the Arctic Circle. Mating takes place in early spring in April-May. In the body of a female, embryos develop within 90 days and are born 8–9 individuals alive.

monitor lizards- a family of large lizards. They live in Africa, South Asia, Australia, on the islands of Oceania. Active during the day. Although they seem slow, they are able to run fast on muscular legs at a speed of 100-120 m / min. A long movable tail is often used when catching prey: the monitor lizard knocks the victim down with it. The tongue is long, partially forked. Monitor lizards are predators: they feed mainly on invertebrates, but they can catch lizards, snakes, birds, rodents, eat eggs of birds and turtles. In the sands of the deserts of Central Asia and South Kazakhstan lives gray monitor lizard up to 1.5 m long.

snakes- scaly reptiles, with a long cylindrical body, an ovoid or triangular head and tail (Fig. 107). The limbs are missing. Only boas and pythons the remains of the hind limbs are preserved in the form of two slightly protruding bones from under the scales. The skin is covered with horny scales, different in size, shape and location. Body length ranges from 12 cm (at burrowing snakes) up to 10 m (for boas).

Snakes move pretty fast. They have developed a special mechanism of movement by means of lateral bends of the spine and ribs, which, with their lower ends, are able to move forward and backward. The ventral transverse shields are also used, clinging to the unevenness of the soil.

Rice. 107. Snakes

The organs of vision are the eyes, which are hidden under a transparent leathery film formed by fused eyelids. The pupil of the eye is in the form of a vertical slit. Snakes have poor vision and poor hearing. They have no external auditory opening.

In the oral cavity is a thin and long tongue, forked at the end. Like lizards, it is an organ of touch, smell, and taste. The tongue is mobile, through a semicircular opening in the upper jaw it is able to protrude outward with the mouth closed. By sticking out and removing the tongue, the snake receives information about the smells in the air, and if it touches the surrounding objects with its tongue, then about their surface, shape and taste. On the lower and upper jaws there are relatively thin teeth of the same type. They serve to capture prey and hold it. From non-venomous snakes water snakes and yellow-bellied snakes have small sharp teeth capable of pushing live prey into the esophagus. Boas, before swallowing, strangle the victim, wrapping it in rings of a muscular body. Poisonous snakes in the upper jaw have two particularly prominent poisonous teeth. Venom is produced by paired venom glands located on both sides of the head behind the eyes. Their ducts are connected with poisonous teeth.

All snakes are predators. They are able to swallow prey many times the thickness of their body. This is facilitated by movable jaws. The lower jaw is movably connected to the bones of the skull, moves forward and goes back, as if on a hinge. Its halves are connected on the chin by a flexible ligament and are able to move apart to the sides.

Approximately 1-2 times a year, snakes molt. The molt proceeds for half an hour or a little more and ends with the shedding of the upper cover - creep out. The molting process itself begins a few days before shedding the skin. It is accompanied by clouding of the eyes, loss of skin luster, sedentary state. The worn cover of the snake usually sheds gradually. At this moment, she vigorously rubs against the branches of shrubs and trees or against stones. The skin is shifted from the head and body in a “stocking” due to the snake crawling and rubbing against protruding solid objects. Everything ends with the complete liberation of the body from the old skin.

Snakes of most species have a protective coloration that is in harmony with the color of the environment. This is necessary for disguise at the time of hunting. Yellowish-sandy coloration is characteristic of many desert species. Coloring tiger python and Gaboon viper bright, motley, like the leaf litter of a tropical forest, which makes the snakes invisible in it. Some snakes have a bright, very contrasting pattern. His snakes demonstrate for intimidation at the moment of danger. For example, spectacle snake from the genus cobras(Fig. 108).

Rice. 108. Spectacle snake

Snakes are common in all parts of the world, but in areas with a hot climate they are much more numerous. They live in various ecological conditions - forests, steppes, deserts, in the foothills and mountains.

Snakes mainly lead a terrestrial existence, but some species live underground, in water, on trees. When adverse conditions occur, for example, as a result of a cold snap, snakes hibernate. They reproduce by laying eggs. Some species are ovoviviparous.

The economic importance of snakes is largely underestimated. Many species of snakes feed on rodents, regulating their numbers in nature. Various medicines are made from snake venom.

Questions

1. What acquired structural features allowed reptiles to completely switch to a terrestrial way of life?

2. What are the characteristic features of snakes?

3. What functions does the tongue of snakes fork at the end perform?

4. What animals belong to the order Scaly? What is their significance in nature and human life?

5. In this connection, the reproduction and development of reptiles is considered more progressive than that of amphibians?

Tasks

1. Based on the knowledge gained in the OBZh course, name the first aid measures for snake bites.

2. Find out which reptiles are protected in your area.

3. Think and discuss with your classmates why the medical emblem has a snake.

Do you know that…

The giant monitor lizard from the Komodo and Flores islands has a body length of up to 3 m. This animal hunts birds, small animals, and eats their corpses. Along with large monitor lizards, small monitor lizards are also known, for example, the length of the Australian short-tailed monitor does not exceed 20 cm.

Poisonous snakes are caught and kept to obtain poison in special nurseries. They are found in tropical Asia, southern Africa, South America, and Central Asia. They contain mainly cobras, gyurz, steppe vipers, etc.

Snakes are cold-blooded animals belonging to the class of reptiles, a detachment of snakes proper, in which there are about 2,000 species that inhabit all parts of the world. Their body is spindle-shaped, elongated; however, three divisions can be distinguished in it; head, body and tail. The body is covered with smooth scales or with a protrusion in the middle in the form of a keel.

Some of them have the form of plates or shields (on the head, belly). All these scaly formations consist of dense horny substance.

A common characteristic of snakes is that in different species of snakes, the scales are colored in different tones and often have spotting. Combinations of color and spots give the appropriate overall tone and pattern typical of the species. Some reptile snakes have a single, mostly dark color, others are very brightly colored. In some, the pattern is modest, in the form of small spots, rarely scattered along the body, in others it is a multi-colored lace.

Studies have shown that the presence of a scaly cover, painted in different colors, is a very important factor in the life of snakes. Strong horny scales, covering their body like tiles, protect snakes well from various injuries. As for the coloring and pattern, they are mostly adapted to the conditions of the surrounding area.

A snake lying motionless is sometimes difficult to notice. , painted in brownish tones, almost completely merges with the general coloring of the steppe scorched by the sun. The Madagascar boa constrictor and the reticulated python have such variegated colors and interwoven patterns that are very suitable for the play of light and shadow in the rainforest.

The general characteristic of snakes is that the skeleton of snakes is represented by a skull and a vertebral column, consisting of 200-430 vertebrae. Starting from II-IV, all vertebrae are equipped with freely ending pointed ribs. These ribs, together with the muscles attached to them, play a large role in movement, especially in burrows and narrow crevices. Relying on one or another group of ribs, the snake glides relatively easily in narrow passages.

The skull of a snake consists of a small brain box and movable bones that make up the jaw apparatus. Due to the fact that reptile snakes quite often swallow very large prey, they have mobile not only the bones of the jaw apparatus, but also other bones of the oral cavity (palatine, pterygoid, scaly and transverse). All these bones are interconnected by highly extensible ligaments.

The mechanism that straightens and folds the poisonous teeth of some snake species is also very peculiar. When opening the mouth, the poisonous teeth straighten, when closing, they fold and adjoin the palate. when worn and broken, they are replaced by new ones (new teeth are constantly laid and are at various stages of development in the upper jaw of the snake up to a fully formed tooth).

The muscles of snakes, like all other cold-blooded animals, are pale. In addition to the numerous intercostal muscles lying in the direction transverse to the body of the snake, there are also longitudinal ones. The muscles of boas are the most powerful. With the help of this muscle, boas are able to strangle even large and strong animals, as well as humans. However, boa constrictor attacks on humans are extremely rare.

Due to the spindle shape of the body, the internal organs of the snake are elongated accordingly. The esophagus and stomach are heavily muscled. The genitourinary system is strongly elongated. The lungs are asymmetrical, and in poisonous snakes and some snakes, the left lung is completely atrophied and there is only one right lung. In vipers, the back of the windpipe is greatly expanded. It has the same structure as the right lung and is actively involved in the act of breathing.

In fact, this so-called tracheal lung plays an even greater role in the process of breathing than the lung itself. The windpipe of snakes in the form of a tube extends into the oral cavity almost to the front edge. Such a device protects the snake from possible suffocation during prolonged ingestion of food.

The act of swallowing itself occurs with abundant wetting of food with saliva. The food is swallowed whole, greatly distending the esophagus and stomach if large enough. In addition to food, many reptile snakes also need water. The spinal cord of the snake in its mass significantly exceeds the head.

Describing snakes, it is necessary to say about their sense organs, that their sense of touch is developed quite well. The function of touch is performed mainly by the tongue. A thin, long, forked tongue at the end received the undeserved name of the sting among the people. Since ancient times, this "sting" was considered the snake's poisonous apparatus. And even now, some little-known people with snakes continue to consider it as a poisonous organ.

However, it has been proven that the language of snakes is similar to the language of all other animals. Its main purpose has also been clarified. It has been established that, in general, it performs not gustatory, but tactile functions, and in this respect provides an invaluable service to snakes. With the help of the language, reptile snakes determine all the objects that they encounter on their way.

The organ of vision of snakes - the eye plays an important role in their life. The iris is colored in different colors. In some species it is red, in others it is yellow, in others it is brown. The pupil of some is round, while others are slit-like. A round pupil is predominantly observed in snakes that lead a daytime lifestyle, a slit-like pupil is mainly observed in snakes that hunt at night. The sense of smell in snakes is well developed. They orientate themselves in smells and to a certain extent distinguish between the subtler ones. It is even believed that snakes can follow the trail of their prey and find it.

Snakes lead aquatic, terrestrial and some types of snakes underground lifestyle. Some of them are most active during the daytime, while others hunt mainly at dusk. Reptiles have in common that they are all cold-blooded animals, so some of them, living in countries with a temperate climate, climb into deep holes with the onset of cold weather and fall asleep until spring.

This state in science is called anabiosis. A drop in snake activity is observed not only in cold weather, but also on very hot summer days in the tropics, when the soil is heated and the sun's rays burn. At such a time, reptile snakes go into deep shade, into crevices in the soil and burrows and remain motionless, losing activity.

The general characteristics of snakes indicate that they are all predatory animals, but the nature of food is different for different species and ages. Some types of snakes prey on lizards, others on rodents, others on birds, fourth on fish, and so on. Many eat lizards, rodents, and birds. Young snakes mostly pursue insects, as they cannot cope with large prey.

Snakes destroy many animals that serve them as food, but they can also starve for a long time. They do not feed throughout the winter, when they are in a state of suspended animation (hibernation). Fasting can last 7-8 months or even more. The ability for long-term starvation is not the same in different species.

Did you like the article, was it useful or did you learn something new? Please express your opinion in the comments below. In addition, my gratitude to you will know no bounds if you tell your friends and acquaintances about what you have read, and just good people on social networks. Run a little through the buttons, which are located just below.

Snakes are one of the most peculiar creatures on earth. Their unusual appearance, original way of movement, many remarkable features of behavior, and finally, the poisonousness of many species - all this has long attracted attention and aroused keen interest among people. The most diverse peoples of the globe have many legends, fairy tales and myths about snakes. All these fantasies, reinforced at times by an unconscious superstitious fear of snakes, are so closely intertwined with real facts that many "true" stories about snakes are much more fantastic than any myths. The study of snakes gradually exposes the legends and at the same time reveals new remarkable features in the structure and lifestyle of these animals.

At first glance, it seems that snakes are easy to distinguish in appearance from all other reptiles. Indeed, they have a long, legless torso, dressed in scales, their eyes are always covered with a transparent leathery shell, they lack an external ear. However, all these structural features can also be found in various lizards. Lizards and snakes are closely related animals, so they are classified only in different suborders within the general squamous order (Squamata).

About thirty signs of external and internal structure distinguish snakes from lizards, but almost all of them "as an exception" are also found in the latter. Thus, only by the complex of all these differences can one reliably separate two suborders of scaly reptiles.

The skull of snakes has the most characteristic and stable features of these animals, which distinguish them from lizards. The structure of the skull provides exceptional extensibility of the mouth of snakes, which allows them to swallow whole prey, which is much thicker than their body.

The bones of the facial part of the skull of most species of snakes are movably connected to each other, and the lower jaw is suspended from the skull by highly extensible ligaments. The elastic ligament also connects the right and left halves of the lower jaw. In addition, the snake's brain is entirely enclosed in a bone capsule, and the interorbital septum is not developed.

The teeth of snakes are well developed and serve to bite, capture prey and push it into the esophagus, but by no means for chewing or tearing the prey, since the prey is swallowed whole. Therefore, all teeth are relatively thin, sharp and bent back. They are located on the upper and lower jaws, and in many snakes also on the palatine, pterygoid and premaxillary bones. In addition to the usual solid teeth, snakes of some families have furrowed or tubular teeth that serve to introduce poison into the body of the victim. Furrowed teeth located in the back of the upper jaw are characteristic of poisonous snakes. Aspid and sea snakes have short fixed tubular teeth in front of the mouth, while vipers and pit vipers have long and mobile tubular teeth mounted on a very short maxillary bone that can rotate. At the same time, the venom-conducting fangs, with the mouth closed, lie along the jaw, pointing back, but when the mouth opens, they become perpendicular, taking a "combat" position.

The belt of the forelimbs in snakes is completely absent, and from the belt of the hind limbs in some snakes (boas, valkovy snakes, blind snakes, narrow-mouthed snakes), small bone rudiments of the pelvis are preserved. In boas and roller snakes, the rudiments of the hind limbs themselves have also been preserved in the form of paired claws on the sides of the anus.

The spine of snakes, due to the disappearance of the limb belts, is not clearly divided into sections. The number of vertebrae is very large, from 141 in the thickest and shortest snakes to 435 in the longest and thinnest. The ribs have exceptional mobility. The sternum is absent, and therefore the ribs can diverge widely to the sides, passing large prey through the digestive tract. In addition, many snakes are able to spread their ribs to the sides, flattening the body, when defending.

The internal organs have undergone a significant change in accordance with the elongated shape of the legless body. All of them have an elongated shape and are arranged asymmetrically. In addition, some of the paired organs lost one half and became unpaired. For example, in the most primitive snakes, both lungs are developed, but the right one is always larger than the left; in most snakes, the left lung completely disappears. Vipers and some other snakes, in addition to the right lung, also have the so-called "tracheal lung", formed by the expanded back part of the trachea. The lung itself in its back part is transformed into a thin-walled air reservoir. It is very stretchy, and the snake can swell strongly when inhaling, and when exhaling, it can emit a loud and prolonged hiss.

The esophagus of snakes is very muscular, which makes it easier to push food into the stomach, which is an elongated bag that passes into a relatively short intestine. The kidneys are strongly elongated in length, and the bladder is absent. The testicles are also elongated; the copulatory organ of males is paired sacs, usually equipped with spines of various sizes and shapes. These sacs lie under the skin behind the anus and turn outwards when aroused.

The nervous system of snakes is characterized by a small brain and a powerful, long spinal cord. This causes, on the one hand, the primitiveness of higher nervous activity and, on the other hand, high coordination, accuracy and reactivity of body muscle movements.

The most important sense organ of snakes is the tongue in combination with Jacobson's organ. The paired Jacobson's organ is a thin chemical analyzer and has two outlets on the upper palate. The snake's tongue protrudes through the semicircular notch of the upper jaw, flutters in the air for several seconds, lightly touching nearby objects with forked tips, and then is drawn inward. Here, the ends of the tongue are thrust into the holes of the Jacobson's organ, and the snake receives information about negligible amounts ("traces") of substances in the air and on the substrate. Thus, by alternately sticking out and retracting its tongue, the snake moves quickly and confidently along the trail of prey, looking for prey, a partner, or a source of water.

Unfortunately, still many people believe; the snake's tongue is a "deadly sting" and, seeing its protruding tips, they confidently declare the snake poisonous and, at every opportunity, sometimes kill a completely harmless animal.

The eyes also play a large role in the orientation of snakes, but most of the vision is not sharp. This, in particular, is due to the fact that the eye is covered with a thin and transparent leathery film formed from the fused eyelids. This film comes off the eye along with the rest of the cuticle during molting. Therefore, before molting, the eyes of snakes become cloudy (the surface layer of the film peels off), and after molting they become especially transparent. The dry film covering the eye gives the snake's gaze the seeming stillness and coldness that frightens so many people and creates myths about the hypnotic power of the snake's gaze. The pupil of the eye in diurnal snakes is round, while in twilight and nocturnal snakes it is often extended into a vertical slit. It has a special shape in whip-shaped snakes, most of all resembling a horizontally located keyhole. This structure of the pupil provides the ability for binocular vision, in which up to 45 ° field of view covers both eyes at once.

The sense of smell of snakes is well developed and serves as one of their guiding senses. The nostrils are located on the lateral or upper edge of the muzzle. In marine, as well as in some sand snakes, the nostrils can be closed with special valves, which prevents water from entering when diving or sand when crawling in its thickness.

The hearing organs are greatly weakened: there is no external auditory opening at all, and the middle ear is also simplified. Only the inner ear is fully developed. Therefore, snakes hear very poorly the sounds propagating through the air, and in the ordinary sense of the word they are almost deaf.

Some snakes have thermal sense organs, or remote thermoreceptors, which allow them to detect heat from the body of their prey at a distance. In pythons, they are represented by shallow pits on the upper labials; in African vipers of the genus Bitis, they have the form of cup-shaped depressions immediately behind the nostrils. These organs are especially highly developed in pit vipers. The paired thermolocator is visible from the outside in the form of pits on the sides of the muzzle between the nostrils and the eye.

The snake's body is covered with horny shields and scales. On the head of many snakes, large shields of a regular and constant shape are grouped in a strict; order typical for each species, and serve as an important feature for the scientific description and definition of species.

The body from above and from the sides is covered with rounded diamond-shaped scales, which are located in longitudinal and diagonal rows, and usually the anterior scales slightly overlap the posterior ones. In some species, the scales may have a hexagonal or trihedral shape and be located in the same plane, without overlap (some sea and warty snakes). Horny scales are smooth or have a more or less pronounced longitudinal keel. Between the horny scales of neighboring longitudinal rows there are areas of thin and soft skin, collected in a small fold hidden under the scales. When swallowing large prey, the longitudinal rows of horny scales diverge, the leathery folds straighten out and the body greatly increases in diameter. The scales of one longitudinal row, on the contrary, are firmly connected to each other.

The belly of the snakes is covered with large transversely elongated shields. Only in some aquatic and burrowing species (warty, part of marine, blind snakes, narrow-mouthed) the body from below, as well as from above, is dressed with small scales. The abdominal shields are interconnected by soft folds of skin, and when large food is swallowed, these folds straighten out, and the abdominal shields diverge in the longitudinal direction. Thus, the covers of the snake have a large extensibility, and on the back and sides - transverse, and on the belly - longitudinal.

The top layer of the skin periodically exfoliates, and molting occurs. When molting, the exfoliated epidermis departs first at the front end of the muzzle, and then is removed from the body of the snake with a stocking. A molting snake is actively moving, rubbing its head against the soil and stones, crawling through cracks, pulling off its old skin. Before molting, the color of the snake becomes whitish, and the eyes become cloudy, but after molting, the snake sparkles with bright fresh colors. Healthy snakes molt 2-4 times a year, and the crawl comes out entirely, while in sick and emaciated snakes, molting occurs more often and the old skin peels off in pieces.

In rattlesnakes, when molting, the end scales remain on the tail in the form of caps and form a special ratchet, which they use to warn large enemies.

The coloration of snakes is very diverse and for the most part adaptable to the color of the natural environment. This is the green color of many tree snakes, yellowish-sandy - in desert species. The coloration of some species, such as the tiger python or the Gaboon viper, seems bright and conspicuous to us when we see them in the zoo. But in natural conditions, among the motley leaf litter under the canopy of the tropical forest, this coloring perfectly hides the snake, dismembering and making invisible the true contours of its body.

Some species, however, have bright colors that make them stand out even in their natural setting. These are primarily coral and garter snakes, royal snakes, in the color of which black, yellow and red transverse rings alternate. This coloring is a warning. The extreme resemblance of non-venomous royal snakes and poisonous asps is often cited as an example of imitative resemblance - mimicry. However, such an explanation does not stand up to criticism: firstly, coral asps very rarely and reluctantly bite and lead a twilight lifestyle, so that predators cannot develop a clear idea about the danger of this color; secondly, the alleged "imitators" - king snakes - are much more widespread than their imaginary "model".

Many snakes that are colored patronizingly have areas of the body with a bright pattern, which they show only at the moment of danger. Such is the spectacle snake - a cobra, straightening the cervical region with a clear pattern of "glasses" on the dorsal side. In other species of snakes, the underside of the tail is painted bright orange, and when defending, the snake raises its tail with the bright side to the enemy and shakes it, sometimes even makes “lunges” with its tail, as if wanting to bite.

Usually, young snakes are colored more brightly and contrastingly, while adults are more uniformly colored.

According to WWW.ANIMALS.Ru

Many people are afraid of snakes. At the same time, it is simply impossible not to note their features and uniqueness. Cold-blooded animals amaze with their behavior, an original way of movement, the strength of the effect of a poisonous substance and an unusual appearance. Snakes are among the chordates. Reptiles are included in the order scaly, suborder snakes. The existence and well-being of cold-blooded animals is greatly influenced by the ambient temperature. The study of snakes reveals the unpredictable traits of reptiles and is gaining a growing audience that cannot but fall in love with this population.

Characteristics and structure of snakes

Until recently, 3,200 species of snakes were known to science, and only 410 species are poisonous. The most interesting and unusual feature of cold-blooded animals is the unique body structure. In length, an adult can grow up to nine meters. The smallest snakes grow up to 10 cm. The same fluctuations apply to the weight of representatives of the scaly order, starting from 10 g and reaching 100 kg. The main distinguishing feature of males is their long tail; they also grow smaller.

The variety of body shapes is simply amazing. There are individuals that have a long and thin body, or, conversely, a short and thick one. Those snakes that live near the sea have a flattened appearance and often resemble a ribbon. The skin of cold-blooded animals is mostly dry, completely covered with scales or peculiar shields. In different parts of the body, the surface is different, for example, on the sides and on the back, the scales are small and resemble tiles (since they overlap each other). The belly of most snakes is "dotted" with wide semicircular plates.

The eyelids of snakes are immobile and seem to be able to hypnotize the victim. Reptiles never blink and even sleep with their eyes open. The unique structure of the skull allows even the smallest individuals to open their mouths enough for a small rabbit to fit into it. This is because the upper jaw is connected to adjacent bones and is mobile, while the elements of the lower jaw are connected by a ligament that is stretched.

Due to the unusual body, the structure of the organs is also unique: they are all elongated and elongated closer to the head. The skeleton has a total of about 200-400 vertebrae, each of which is mobile and connected by ligaments. The snake slides along the ground due to the movement of the shields located on the belly. Thanks to the keratinized layers of the epidermis, cold-blooded animals move quickly without difficulty.

Despite all the features of snakes, reptiles have poor eyesight and hearing. In return, nature endowed them with a wonderful sense of smell and touch. Not the last role in orientation in space is played by the tongue, which is forked at the end. Many researchers call it "sting". Opening its mouth, the snake catches air with its tongue and various particles and elements of the atmosphere stick to it, then the reptile brings the organ to a certain place located in the mouth and smells and tastes.

In most cases, snakes use their venom for self-defense, and this is also one of the ways to kill the victim.

Feeding and hibernation of snakes

What snakes eat depends on the size of the cold-blooded animal. The main diet of reptiles consists of rodents, some types of insects. But the fact remains that all snakes are carnivores. For individuals, it is considered a real delicacy to have breakfast with small chicks or eggs. Thanks to the ability to climb trees, they easily destroy bird nests and enjoy a meal.

Meals are not taken every day. Snakes cope well with hunger and, provided that there is water nearby, individuals may not eat for months. A feature of reptiles is their endurance and patience. Snakes hide among the foliage, wait for prey along the road or on the ground, but the hunt is patient and, as a rule, effective. Animal eaters swallow food from the head, but with caution, so as not to injure themselves from the sharp teeth of the victim. Before this process, individuals try to immobilize the animal by squeezing its body with their rings.

Digested food for 2-9 days. The speed of the process depends on the health of the individual, the ambient temperature, and the size of the prey. To speed up digestion, many snakes expose their abdomen to the sun.

Snakes do not like cold weather, therefore, already in late October - early November, they leave for the winter. Individuals can choose a rodent hole, a haystack, tree roots, cracks, crevices and other places as a dwelling. If reptiles are near people, then they hide in basements, sewer systems, abandoned wells. The hibernation of animals may be interrupted or not occur at all (if cold-blooded animals live in tropical or).

Toward the beginning of April, representatives of the squamous order begin to crawl out of their shelter. The exact "out of torpor" time depends on the level of humidity, temperature and other factors. Almost all spring, snakes bask in the sun. In summer, during the daytime, animals prefer to be in the shade.

Numerous families of snakes

Experts disagree on the number of families in the suborder of snakes. Here is the most popular classification of reptiles:

• Already-shaped - this family has more than 1500 species. Among them are a wide variety of snakes, differing in color, shape, pattern and habitat. Representatives of this group grow from 10 centimeters to 3.5 meters. They include aquatic and terrestrial, burrowing and arboreal cold-blooded. More than half of the snakes are non-venomous and are often kept in terrariums. However, false snakes are considered poisonous representatives of this group, as they have large teeth with grooves along which a dangerous substance flows.
• Vipers - the family includes more than 280 species. Most often, viper snakes are found on continents such as Asia, North America, Europe and Africa. The body length of cold-blooded animals varies from 25 cm to 3.5 m. Representatives of this family have light zigzag or rhombic patterns on their sides and back. All individuals have long fangs that secrete poison.
• Aspid - there are about 330 species of snakes. This group of reptiles is poisonous. Individuals grow in length from 40 cm to 5 m. You can meet cold-blooded on such continents as Asia, Africa, America and Australia.
• Blind snakes - the family includes about 200 species. Snakes of this group live almost all over the planet.

Thanks to the ability to adapt, snakes can be found in any part of the world. Despite belonging to the same family, animals have a variety of shapes, colors, differ in color, habitat and other features.

The brightest representatives of snakes

Among the wide variety of snakes, the most striking subspecies are snakes, vipers, asps, sea, pit-headed and false-footed cold-blooded. The following reptiles are considered the most interesting and unusual.

Hamadryand (royal cobra)

If you collect all the snakes together, then the Hamadryanda will surpass the rest. This type of animal-eating is considered the largest, even gigantic and poisonous. The king cobra grows up to 5.5 meters, there is no antidote after its bite today. Terrible poison in 15 minutes kills the victim. In addition, it is the Hamadriands that can eat their own kind. Females can starve for three months, carefully guarding their eggs. On average, cobras live for about 30 years and most often they can be found on the territory of the state of India and the islands of Indonesia.

Desert taipan (fierce snake)

It is quite possible to meet a land killer in the desert or on the plains of Australia. Quite often, individuals of this species grow up to 2.5 meters. The venom of a cruel snake is 180 times more powerful than that of a cobra. The color of a cold-blooded animal depends on weather conditions. So in the heat, taipans have straw-like skin, and in the cold - dark brown.

Black Mamba

The maximum height of the black mamba is 3 meters. The representative of reptiles is considered the fastest (individuals can move at a speed of 11 km / h). A venomous snake kills its prey in just a few seconds. However, the animal is not aggressive and can attack a person only when it feels threatened. The black mamba got its name because of the color of the mouth strip. The skin of a predator is olive, green, brown, sometimes with an admixture of metal.

Cassava (Gaboon viper)

Big, fat, poisonous - this is how the Gaboon viper can be characterized. Individuals grow up to 2 meters in length, and have a body girth of almost 0.5 meters. The main feature of the animals is the unique structure of the head - it has a triangular shape and small horns. This type of snake can be classified as calm. The females are viviparous.

Anaconda

Anacondas are included in the family of boas. These are the largest snakes, the length of which can be 11 meters and weight - 100 kg. "Water boa" lives in rivers, lakes, creeks and belongs to non-poisonous reptiles. The main food of cold-blooded animals is fish, waterfowl, iguanas and caimans.

Python

A giant non-venomous snake, reaching 7.5 meters in length. Females differ from males in their powerful body and large size. Pythons prefer to eat small to medium sized mammals. They can easily swallow a leopard, a jackal and digest prey for many days. Snakes of this type incubate eggs, maintaining the desired temperature.

Egg-eaters (African egg snakes)

Animals feed exclusively on eggs and grow no more than 1 meter in length. Due to the unique structure of the skull, small snakes easily swallow large prey. The cervical vertebrae break the shell, and the contents of the eggs are swallowed, the shell is expectorated.

radiant snake

Non-venomous snakes with excellent body color. Individuals grow up to 1 meter and feed on lizards, small rodents.

Worm Snake

Small representatives of reptiles (length does not exceed 38 cm) look like earthworms. They can meet under a stone, in thickets of bushes, rocky slopes.

Non-venomous snakes

Non-poisonous snakes include the following representatives of cold-blooded animals:

ordinary snake

Common snake - distinctive features are yellow or orange spots located on the sides of the head;

Amur snake

Amur snake - the length of the animal can reach 2.4 m, belongs to the already-shaped family;

Copperhead common

Other non-venomous snakes include the tiger and reticulated python, milk snake, maize snake, yellow-bellied snake and Aesculapius snake.

tiger python

reticulated python

milk snake

yellow-bellied snake

Poisonous snakes

Gyurza

Gyurza is one of the most dangerous poisonous snakes. The length of individuals rarely exceeds two meters.

In Asia, there is such a dangerous predator as efa. Snakes of this type are afraid of people and warn them of their presence by hissing. Cold-blooded snakes grow up to 80 cm and are viviparous snakes.

A special place in the list of poisonous snakes is given to rattlesnakes (pit-headed) representatives of reptiles. They are one of the most dangerous animals on the planet, known for their rattle-like tail.

snake breeding

Cold-blooded animals love to be alone. But during the mating season, they become very friendly and loving. The "dance" of males can last for many hours before the female consents to fertilization. Most snakes are oviparous animals, but there are some species that give birth to live young. A snake clutch can reach 120,000 eggs (this process is influenced by the habitat and the type of reptile).

Sexual maturity in snakes occurs in the second year of life. The female is searched for by smell, after which the males wrap around the body of the chosen one. Surprisingly, the parents of newborns do not pay the slightest attention to them.

Conclusion

Snakes are extraordinary creatures that differ from each other in size, shape, skin color and habitat. The unique body structure, interesting lifestyle and character of individuals make them a bright object for research.