What acquired structural features allowed. Class Reptiles or Reptiles
Question 1. What acquired structural features allowed reptiles to completely transition to a terrestrial lifestyle?
Adaptations of reptiles to a terrestrial lifestyle:
1) keratinization of the skin and the absence of glands that would moisturize the skin, which is associated with saving water and protecting against evaporation;
2) pulmonary respiration, which provides oxygen from the atmosphere;
3) ossification and development of the skeleton (especially the cervical and thoracic spine, free limbs and their girdles) and the muscular system, which allows active movement in a ground-air environment less dense than water;
4) internal fertilization, the laying of fertilized eggs with a large supply of nutrients, covered with protective membranes, which gives complete independence from the aquatic environment for reproduction.
Question 2: What are the characteristic features of snakes?
Snakes have no free limbs. They have developed a special mechanism of movement by lateral bending of the spine and ribs. Snakes have poor vision and poor hearing. They do not have an external auditory opening. The eyes are hidden under a transparent leathery film formed by fused eyelids (unblinking gaze). Poisonous snakes have two particularly large venomous teeth in their upper jaw. The venom is produced by paired venom glands located on both sides of the head behind the eyes. Their ducts are connected to poisonous teeth.
All snakes are predators. They are capable of swallowing prey many times greater than their body thickness. This is facilitated by special joints of the jaws. The lower jaw is movably connected to the bones of the skull and is capable of moving forward and moving back, as if on a hinge. Its halves are connected at the chin by a flexible ligament and can be moved apart.
Question 3. What functions does the forked tongue of snakes perform?
The tongue of snakes is an organ of touch, smell, and taste. Through a semicircular hole in the upper jaw, the tongue can protrude outward when the mouth is closed. By sticking out and retracting its tongue, the snake receives information about the odors in the air, and when it touches surrounding objects with its tongue, it receives information about their surface, shape and taste.
Question 4. What is the significance of squamates in nature and human life?
Most scaly reptiles are carnivores or insectivores. Many species of snakes feed on rodents, regulating their numbers in nature.
Poisonous snakes can be dangerous to human life and health, but only if the person behaves carelessly or inattentively. The venom of some snakes (for example, the spectacled snake - cobra) is very valuable; various medicines are made from it.
Question 5. Why is the reproduction and development of reptiles considered more progressive than that of amphibians?
The appearance of internal fertilization and egg shells in reptiles is the most important adaptation to a terrestrial lifestyle and, accordingly, a progressive feature. Most of their representatives reproduce by laying eggs covered with a leathery shell (in lizards and snakes) or a calcareous shell (in crocodiles and turtles), but so-called ovoviviparity is also observed, during which the hatchlings emerge from the eggs (freeing them from the egg shells) in mother's body. Ovoviviparity is typical for reptile species living in a temperate climate zone (many lizards, common vipers, some snakes), or for those that have switched to a completely aquatic lifestyle (sea snakes).
Reptiles, compared to amphibians, represent the next stage in the adaptation of vertebrates to life on land. They are the first true class of land vertebrates. They live mainly in regions with warm and hot climates. During the conquest of land, reptiles acquired a number of adaptations:
The body is divided into head, neck, torso, tail and five-fingered limbs.
The skin is dry, devoid of glands and covered with horny cover, protecting the body from drying out. The growth of the animal is accompanied by periodic molt.
Skeleton durable, ossified. The spine consists of five sections: cervical, thoracic, lumbar, sacral and caudal. The shoulder and pelvic girdles of the limbs are strengthened and connected to the axial skeleton. The ribs and chest are developed.
The musculature is more differentiated than in amphibians. Developed cervical and intercostal muscles, subcutaneous muscles. The movements of the body parts are more varied and faster.
The digestive tract is longer than that of amphibians and is more clearly differentiated into sections. Food is captured jawtami, having numerous sharp teeth. The walls of the mouth and esophagus are equipped with powerful muscles that push large portions of food into the stomach. At the border of the small and large intestines there is cecum, especially well developed in herbivorous terrestrial turtles.
Respiratory system - lungs - have a large respiratory surface due to their cellular structure. Developed airways - trachea, bronchi, in which the air is moistened and does not dry out the lungs. Ventilation of the lungs occurs by changing the volume of the chest.
Heart three-chamber, however, the ventricle has an incomplete longitudinal septum, which prevents complete mixing of arterial and venous blood. Most of the body of reptiles is supplied with mixed blood with a predominance of arterial blood, so the metabolic rate is higher than that of amphibians. However, reptiles, like fish and amphibians, are poikilothermic (cold-blooded)ny) animals, whose body temperature depends on the temperature of their habitat.
Excretory organs – pelvic kidneys. Urine flows through the ureters into the cloaca, and from it into the bladder. In it, water is additionally sucked into the blood capillaries and returned to the body, after which urine is excreted. The end product of nitrogen metabolism, excreted in the urine, is uric acid.
The brain has a larger relative size than that of amphibians. The cerebral hemispheres of the forebrain with rudiments are better developed bark and cerebellum. The forms of behavior of reptiles are more complex. Sense organs are better adapted to a terrestrial lifestyle.
10. Fertilization only internal. Reptiles lay eggs protected from drying out by a leathery or shell membrane. on the land. The embryo in the egg develops in a watery shell. Development direct.
Features of the structure and life processes .
Let's look at the structure of the main organs of reptiles using the example spinning lizards.
The lizard's body is divided into head, torso and tail. In the trunk section the neck is well defined. The entire body is covered with horny scales, and the head and belly are covered with large scutes. The limbs of the lizard are well developed and armed with five fingers with claws.
The humerus and femur bones are parallel to the surface of the ground, causing the body to sag and touch the ground (hence the name of the class). The cervical spine consists of eight vertebrae, the first of which is movably connected to both the skull and the second vertebra, which provides the head with greater freedom of movement. The vertebrae of the thoracolumbar region bear ribs, some of which are connected to the sternum, resulting in the formation of the rib cage. The sacral vertebrae provide a stronger connection to the pelvic bones than in amphibians.
In lizards, when the tail spontaneously drops (the phenomenon of autotomy), the gap occurs not between the vertebrae, but in the middle, where there are thin cartilaginous layers dividing the vertebral body into two parts.
Excretory organs are represented by pelvic kidneys, in which the total filtration area of the glomeruli is small, while the length of the tubules is significant. This promotes intensive reabsorption of water filtered by the glomeruli into the blood capillaries. Consequently, the excretion of waste products in reptiles occurs with minimal water loss. In them, like in terrestrial arthropods, the end product of excretion is uric acid, which requires a small amount of water to be excreted from the body. Urine is collected through the ureters into the cloaca, and from it into the bladder, from which it is excreted as a suspension of small crystals.
Brain Reptiles, compared to those of amphibians, have a better developed cerebellum and cerebral hemispheres of the forebrain, the surface of which has the rudiments of the cortex. This causes various and more complex forms of adaptive behavior.
Sense organs more consistent with a terrestrial way of life. The eyes are protected by movable eyelids (upper and lower) and a nictitating membrane. Focusing of vision is achieved both by moving the lens relative to the retina and by changing its curvature. Some diurnal species have color vision. Lizards have a well-developed parietal eye, a light-sensitive organ located on the crown.
Rice. 41. Lizard brain: I - top; II - bottom; III - side; 1 - forebrain; 2 - striatum; 3 - midbrain; 4 - cerebellum; 5 - medulla oblongata; 6 - funnel; 6" - pituitary gland; 7 - chiasm; 8 - olfactory lobe; 9 - pineal gland.
Hearing organ consists of the middle and inner ear. The sense of smell is better developed than in amphibians.
Some species of snakes have a thermal sense organ (between the nostrils and the eye), which allows them to sense the heat emanating from their prey at a distance. This makes it possible for snakes to hunt warm-blooded animals without seeing them.
In reptiles, fertilization is internal. They reproduce by laying eggs or ovoviviparity. The eggs are relatively large and rich in nutrients, which ensures direct development of the embryo without intermediate larval stages. The eggs are protected from drying out by protective shells (leathery or shell). The embryo in the egg develops in a cavity filled with fluid, which contributes to the proper formation of its organs.
Diversity and importance of reptiles
Modern reptiles are only small remnants of a rich and diverse world of animals that inhabited not only all the land, but also all the seas of the planet in the Mesozoic era. Currently, the class Reptiles includes more than 7 thousand species, united in several orders, among which the most numerous are Scaly, Crocodiles, Turtles and Beaked.
Order Scaly ( Sguamata ) – the largest group of reptiles (approximately 6.5 thousand species). They are characterized by the presence of horny scales in their integument.
In the central zone of the CIS the sand lizard lives, the viviparous lizard is common to the north, and the southern regions are inhabited by geckos, agamas and the largest lizard - the gray monitor lizard (up to 2 m long). Thanks to its well-developed limbs, the monitor lizard runs quickly, its body raised high above the ground. Monitor lizards are widespread in Africa, South Asia, the Malay Archipelago and Australia, as well as in the sandy deserts of Turkmenistan and Uzbekistan.
Snakes are legless, scaly animals with a long cylindrical body, using the wavy curves of which they move. They do not have movable eyelids. Prey is swallowed whole thanks to a widely extensible mouth (the lower jaws are suspended on extensible ligaments). The teeth are sharp and directed backwards. When attacking a prey, poisonous snakes move their teeth forward from the oral cavity and with their help introduce the secretion of poisonous glands into the body of the prey. The sternum is missing. The ribs are free and extremely mobile. The middle ear is simplified, the eardrum is absent. Distributed in all parts of the world, but numerically predominant in hot countries. Non-venomous snakes are widely known - snakes, boa constrictors, and poisonous ones - viper, viper, rattlesnake, sand ephas, etc. Snake venom is used to prepare medicines.
Squad Crocodiles ( Crocodylia ) represented by large (up to 6 m long), the most highly organized reptiles, adapted to a semi-aquatic lifestyle. They have a lizard-like, slightly flattened body, covered with horny scutes, with a laterally compressed tail and swimming membranes between the toes of the hind legs.
Rice. 42. Crocodiles: 1 - gharial; 2 - Nile crocodile; 3 - Chinese alligator
The teeth sit in cells (like in mammals). The bases of the teeth are hollow inside, and new, replacement teeth develop in these cavities. There are multiple changes of teeth during the life of a crocodile. The lungs have a complex cellular structure and hold a large supply of air. The diaphragm is developed. The heart is four chambered.
They reproduce by laying eggs (10-100 eggs) covered with a calcareous shell. They become sexually mature at 8-10 years of age and live up to 80-100 years.
Known are the Nile crocodile (Africa), alligator (China, America), caiman (America), gharial (Hindustan, Burma). In some countries, crocodile meat is used in food, and the skin is a valuable raw material for the manufacture of haberdashery. Due to intensive fishing, the number of crocodiles has sharply decreased. Farms for their breeding have been created (USA, Cuba).
Turtle Squad ( Testudines ) unites reptiles that have a compact body enclosed in a durable bony shell into which the neck, head, limbs and tail can be retracted. The top of the bone shell is covered with horny plates or soft skin.
Rice. 43. Turtles: 1 - elephant turtle; 2 - steppe tortoise; 3 - marsh turtle; 4 - carriage; 5 - Ussuri soft-skinned turtle.
The jaws are devoid of teeth and have sharp horny edges. The vertebrae, except for the cervical and caudal sections, are fused to the dorsal part of the shell (as are the ribs). The breathing mechanism is associated with the movement of the neck and shoulders, which, moving out from under the shell, stretch the lungs. The metabolic rate is low. Capable of prolonged fasting. They live in humid tropics and hot deserts. In many countries, turtle meat and eggs are eaten. The horny plates of some turtle species are used to make crafts. Swamp turtle - lives in weakly flowing water bodies and feeds on a variety of small aquatic and terrestrial animals.
Lives in the Galapagos Islands elephant turtle. The huge shell can be up to 110 cm long and up to 60 cm high. Thick and powerful columnar legs support the heavy body. The mass of adult specimens is about 100 kg, and individual giants weigh up to 400 kg.
The only type of modern Beakheads ( Rhynchocephalia ) – tuateria has many extremely primitive features and is preserved only in New Zealand and the surrounding islands.
Rice. 44. Hatteria.
Hatteria looks very much like a lizard with a massive body, large head and five-fingered limbs. A low ridge of triangular vertical plates stretches from the back of the head along the back and tail. The hatteria is painted in a dull olive green color, with small and larger yellow spots on the sides of the body and limbs.
The pupils of the large eyes, located on the sides of the head, are in the form of a vertical slit. The tuateria does not have eardrums; the middle ear cavity is filled with adipose tissue.
The body of adult males is up to 60 cm long, weighing 800 g. Females are almost twice as small as males. Hatteria reaches maturity only at 20 years of age. Life expectancy is also long: in captivity, tuataria lived for more than 70 years.
The main food of the tuateria is various invertebrates, especially insects, in particular beetles and large wingless grasshoppers, as well as spiders, worms, mollusks, sometimes lizards, frogs, and bird eggs. The hatteria swallows its prey whole.
The tuateria moves slowly, while hardly raising its belly above the substrate. However, when hunting or in a frightened state, it rises to its feet and moves quickly. In addition, she is a good swimmer and willingly goes into the water.
Origin of reptiles. Reptiles have been known since the end of the Carboniferous period of the Paleozoic era. They reached their heyday in the Mesozoic era, by the end of which they were replaced by birds and mammals. The ancestors of modern reptiles are considered to be primitive Devonian amphibians - stegocephalians, which gave rise to cotilosaurs - ancient reptiles.
The flourishing of ancient reptiles in the Mesozoic era was facilitated by a warm climate, an abundance of food both on land and in water, as well as a lack of competitors. They inhabited a terrestrial environment dominated by giant dinosaurs, reaching a length of 30 m. Among them were both herbivores and predators. The aquatic environment was dominated by fish-like lizards - ichthyosaurs (8 - 12 m). A peculiar group consisted of pterosaur lizards, which could fly thanks to a large leathery membrane stretched between the fore and hind limbs.
The extinction of ancient reptiles is associated with the cooling of the climate at the end of the Mesozoic and their inability to maintain a constant body temperature. The resulting decline in vital processes in reptiles led to a weakening of their competition with the newly emerging and rapidly progressing mammals.
Control questions:
What is the peculiarity of the organization of reptiles?
What orders are included in the class of reptiles?
What features of the skeletal structure are inherent in reptiles?
What is autotomy in reptiles?
What reproductive features are characteristic of reptiles?
Why are these animals called reptiles?
The limbs of reptiles are attached to the sides of the body, widely spaced. Therefore, when moving, the body sags and touches the ground (creeps).
Which ones live in your area?
The central region of Russia is inhabited by the viper, quick lizard, grass snake, and steppe tortoise.
Questions
1. What acquired structural features allowed reptiles to completely transition to a terrestrial lifestyle?
Dry body coverings, keratinized on top, cellular lungs, and internal fertilization allowed reptiles to switch to a terrestrial lifestyle. The structure of the skeleton of reptiles allowed them to move faster and turn their heads, which is also important when living in a terrestrial environment.
2. What are the characteristic features of snakes?
Snakes have no limbs. They move, bending the body, due to powerful muscles and numerous ribs, the ends of which protrude through the skin. With them the animal clings to uneven soil. Unlike lizards, snakes have an unblinking gaze, since their eyes are covered with transparent fused eyelids. Snakes are able to “stocking” crawl onto their prey thanks to their expanding, movable jaws. Snakes don't see well. The forked tongue of snakes is an organ of touch, smell, and taste. Poisonous snakes have poisonous teeth.
3. What functions does the forked tongue of snakes perform?
The tongue of snakes performs the functions of touch, smell, and taste.
4. What animals belong to the order Squamate? What is their significance in nature and human life?
The order Squamate includes lizards, monitor lizards, and snakes. Most lizards and snakes, eating insects, rodents and terrestrial mollusks that harm agriculture, benefit humans. In some countries in South America, South Asia and Africa, non-venomous snakes are kept instead of cats. In nature, reptiles exist in a common system of food connections: some eat plants, others eat animals (insects, amphibians, reptiles, small animals), and they, in turn, are eaten by other predators - birds of prey and animals.
The bites of poisonous snakes are dangerous. However, studying the effect of snake venoms has made it possible to create valuable medicinal preparations based on them, which are used in the treatment of diseases of the respiratory organs, heart, and joints. Large snakes are harvested for beautiful and durable leather. Among reptiles there are herbivorous and insectivorous species. Most are predators. By eating plants, insects, amphibians, and small animals, reptiles regulate their numbers.
5. Why is the reproduction and development of reptiles considered more progressive than that of amphibians?
Fertilization in reptiles is internal. Seminal fluid enters the female's genital tract when the cloaca of the male and female come together. The embryo in the fertilized egg develops already when the egg moves along the oviduct and becomes covered with egg membranes. They provide the embryo with water and protect it from damage and shock. Sometimes the babies develop in the mother's body. In these cases, ovoviviparity occurs. For example, in the viper and the viviparous lizard, the young hatch from the egg when it is laid. Reptile eggs are supplied with sufficient nutrients. The eggs hatch into full-fledged individuals, not larvae.
Tasks
Based on the knowledge acquired in the life safety course, name first aid measures for snake bites.
Snake bite: first aid
The victim should be immediately laid down and provided with complete rest, since any movement increases blood circulation, and therefore the penetration of poison into the body.
In the very first minutes, you need to open the wound with pressure and begin to suck out the poison, spitting it out regularly. Do this for 15 minutes. Don’t be afraid to poison yourself: sucking poison out of a wound is not a dangerous procedure at all. Just don't swallow the poison.
Disinfect the wound with any disinfectant at hand - iodine, alcohol, brilliant green.
Apply a sterile bandage to the affected area, which should be loosened as the limb swells.
Give the victim something to drink and take him to a medical facility as soon as possible.
If you notice that the victim has gone into shock, try to bring him out of this state. If he stops breathing, begin artificial respiration.
If the victim loses consciousness, but his breathing does not stop, turn him over onto his chest and place him in a position that is safe for breathing.
Apply a tourniquet to the affected limb.
Cut, cauterize and generally injure bite wounds.
Burning the wound with hot metal, matches, potassium permanganate powder, etc. - this damages the tissue even more.
Giving the victim alcohol: the nervous system will only react more strongly to the poison, which will also linger more firmly in the body.
Find out which reptiles are protected in your area?
Reptiles of the Red Book of the Moscow Region: quick lizard, brittle spindle, common grass snake, copperhead, common viper.
Think and discuss with your classmates why a snake is depicted on the medical emblem?
The origin of the medical emblem - a bowl entwined with a snake - is lost in ancient times. Over the centuries of its development, medicine has had many different emblems, but this image has become the most widespread. The image of a snake has long attracted people's attention. In primitive society, during the period of matriarchy, when there was a cult of animals, the snake was considered sacred, and in the ancient world it personified power, wisdom, knowledge, as evidenced by the folklore of the peoples of all continents. Ancient legends attribute to snakes the ability to understand the conversation of herbs and recognize their healing powers. In many fairy tales of different peoples, the snake was considered a symbol of wisdom; whoever tasted snake meat, they said, acquired the gift of clairvoyance.
In the most ancient images of the medical emblem, the snake appears without a bowl. The cup appeared later. It symbolized the birth of life, life itself, the protection of life and the struggle for life. In ancient times, diseases were treated with water, herbs and animal products. The cup acted as an object that had magical healing powers and symbolized the presence of a good healing principle. In slave states, the cup played a major role in ritual sacrifices. In Ancient Egypt and Ancient Greece, the cup symbolized the protection of health and the affirmation of life. In ancient mythology, the drink of immortality was drunk from the cup of the gods.
At first, the bowl and the snake were depicted separately, then at the beginning of the 17th century they were joined together.
In the modern medical emblem, the snake represents wisdom, knowledge, immortality, and the bowl is a vessel for medicinal poison. The leading place in the emblem belongs to the snake, and the bowl has an additional meaning and cannot separately serve as an emblem of medicine.
Question 1. What acquired structural features allowed reptiles to completely transition to a terrestrial lifestyle?
Adaptations of reptiles to a terrestrial lifestyle:
1) keratinization of the skin and the absence of glands that would moisturize the skin, which is associated with saving water and protection from evaporation;
2) pulmonary respiration, which provides oxygen from the atmosphere;
3) ossification and development of the skeleton (especially the cervical and thoracic spine, free limbs and their girdles) and the muscular system, which allows active movement in a ground-air environment less dense than water;
4) internal fertilization, the laying of fertilized eggs with a large supply of nutrients, covered with protective membranes, which gives complete independence from the aquatic environment for reproduction.
Question 2: What are the characteristic features of snakes?
Snakes have no free limbs. They have developed a special mechanism of movement by lateral bending of the spine and ribs. Snakes have poor vision and poor hearing. They do not have an external auditory opening. The eyes are hidden under a transparent leathery film formed by fused eyelids (unblinking gaze). Poisonous snakes have two particularly large venomous teeth in their upper jaw. The poison is produced by paired poisonous glands located on both sides of the head behind the eyes. Their ducts are connected to poisonous teeth.
All snakes are predators. They are capable of swallowing prey many times greater than the thickness of their body. This is facilitated by special joints of the jaws. The lower jaw is movably connected to the bones of the skull and is capable of moving forward and moving back, as if on a hinge. Its halves are connected at the chin by a flexible ligament and can be moved apart.
Question 3. What functions does the forked tongue of snakes perform?
The tongue of snakes is an organ of touch, smell, and taste. Through a semicircular hole in the upper jaw, the tongue can protrude outward when the mouth is closed. By sticking out and retracting its tongue, the snake receives information about the odors in the air, and when it touches surrounding objects with its tongue, it receives information about their surface, shape and taste.
Question 4. What is the significance of squamates in nature and human life?
Most scaly reptiles are carnivores or insectivores. Many species of snakes feed on rodents, regulating their numbers in nature.
Poisonous snakes can be dangerous to human life and health, but only if the person is careless or inattentive. The venom of some snakes (for example, the spectacled snake - cobra) is very valuable; various medicines are made from it.
Question 5. Why is the reproduction and development of reptiles considered more progressive than that of amphibians? Material from the site
The appearance of internal fertilization and egg shells in reptiles is the most important adaptation to a terrestrial lifestyle and, accordingly, a progressive feature. Most of their representatives reproduce by laying eggs covered with a leathery shell (in lizards and snakes) or a calcareous shell (in crocodiles and turtles), but so-called ovoviviparity is also observed, during which the hatchlings emerge from the eggs ( their release from the egg membranes) occurs in the mother’s body. Ovoviviparity is typical for reptile species living in a temperate climate zone (many lizards, common vipers, some snakes), or for those that have switched to a completely aquatic lifestyle (sea snakes).
