The class of vertebrates that occupy an intermediate position between amphibians and mammals is called reptiles. They are more similar to birds. The following animals belong to this class according to the list:
- crocodiles;
- turtles;
- snakes;
- lizards;
- dinosaurs (fossil form of animals of the Mesozoic era).
General characteristics of reptiles
Like amphibians, reptiles are cold-blooded creatures. In other words, their body temperature is determined by their surroundings. To some extent, reptiles are able to regulate their temperature by covering themselves against hypothermia. For example, in the winter season, animals hibernate, and during periods of extreme heat they begin hunting at night.
Reptiles have tough skin covered with scales. The main task of which is to protect the body from drying out. For example, in turtles the upper protection is provided by a durable shell, crocodiles have hard plates of bone origin on their head and back.
Reptiles breathe only through the lungs. In some animal species, the lungs are the same size and equally developed, while in others, such as snakes and lizards, the right lung is larger and is located throughout the body cavity. Turtles have fixed ribs due to their shell, so the ventilation of the body is organized in a different way. Air enters the lungs during rocking movements of the front legs or during intense swallowing.
The bony skeleton of reptiles is quite well developed. The number and shape of ribs depends on the specific species, but all representatives of the class have them. Almost all turtles have fused bony plates of the shell and spine. Snakes have ribs designed for active crawling. In lizards, the ribs serve to support fan-shaped membranes for gliding in the air.
Most reptiles have a short tongue that cannot protrude. Snakes and lizards have a long tongue, divided in two, which can extend far from the mouth. For this species of animal these are the most important sense organs.
To protect themselves from the environment, small reptiles have original coloring. Turtles are reliably protected by a dense shell. Some snakes are poisonous.
In terms of reproductive organs, reptiles are similar to birds. As a rule, reptiles are oviparous animals. But in some species, eggs remain inside in the oviduct until hatching. This type includes some species of lizards and vipers.
Classification of reptiles and their distribution
Modern reptiles are divided into four groups:
- turtles (about 300 species);
- crocodiles (25 species);
- scaly (about 5,500 species of lizards and snakes);
- tuatara (tuatara).
The last order belongs to the only representative of beaked animals among reptiles.
Reptiles distributed throughout the world. The greatest numbers are seen in warm areas. In regions with a cold climate and a lack of woody vegetation, reptiles are practically not found. Representatives of this class live on land, in water (fresh and salty) and in the air.
Ancient reptile fossils
Reptiles have been known since the Carboniferous period. They reached their largest sizes in the Permian and Triassic periods. At the same time, there was an increased reproduction of animals that populated more and more new territories. In the Mesozoic era, the dominance of reptiles was overwhelming, both on land and in water. It is not for nothing that this period was called the Age of Reptiles.
Turtles
One of the most famous species of reptiles are turtles. There are both marine and land representatives of animals. The species is distributed throughout the world. Animals are also allowed keep at home. The most ancient representatives of turtles were discovered 200 million years ago. Scientists believe that they descended from a primitive species of cotylosaurs. Turtles are practically harmless animals, they are not dangerous to people.
Animals of this species have a shell of a bone structure. On the outside, it is formed by numerous individual elements of horny tissue, which are connected by plates. Land turtles have excellent lung function for breathing. Aquatic representatives of the class breathe using the mucous membrane of the pharynx. The main feature of these animals is longevity. The average age of turtles exceeds the lifespan of any other reptile.
Crocodiles
Animals are one of the most dangerous species of reptiles. The origin of crocodiles is associated with ancient reptiles, the size of which exceeded 15 meters in length. Scientists have been able to find the remains of ancient crocodiles on all continents of the globe. Modern representatives of this class have more conventional sizes. But among reptiles they still remain the largest species.
Almost all the time crocodiles are in the water. Only the ears, nose and eyes of the animal appear on the surface. Crocodiles swim with the help of webbed tails and paws. But at great depths, only single representatives of the class can exist - the comb species. Crocodiles' nests are located on land. In some cases, they also crawl out of the water to warm themselves.
Reptiles have a strong, powerful tail and are also characterized by high speed of movement on land. Therefore, crocodiles are extremely dangerous to humans. A sudden sudden burst can take people by surprise. Alligators are considered the most dangerous representatives of crocodiles.
Chameleons
This type of lizard is known to almost everyone. Reptiles are known for their unique coloration, which serves as a camouflage feature. An animal's skin can change color depending on environmental conditions. Chameleons live in trees. Some people keep these cute creatures at home.
Reptiles are quite finicky to care for. They need a spacious terrarium, which is equipped with special lamps. You will need wood, a small pond, heated floors and excellent ventilation. Chameleons feed on insects. Therefore, the owners will also have to take care of their availability.
Iguanas
Currently, there are more and more lovers of pets - iguanas. This representative of lizards also requires special care. Iguanas must be kept in a special terrarium that can maintain a certain temperature regime. For food, domestic iguanas prefer fresh fruits and vegetables, as well as greens. With good care and optimal living conditions, lizards at home can grow quite large. Maximum iguana weight - 5 kg. It is difficult to keep such a pet at home; it will require a large financial investment, as well as significant labor costs.
Iguanas are among those rare species of reptiles that molt. Most reptiles experience this period in two days, but in iguanas it lasts for several weeks.
Monitor lizards
There are about 70 species of monitor lizards. They live in different territories. The size of the animals is very impressive. Short-tailed monitor lizards have a length of about 20 cm, while other representatives have a much longer length (about 1 meter). The largest monitor lizards are the Komodo species. Their dimensions reach three meters in length, and their weight is 1500 kg. It’s not for nothing that such animals are called modern dinosaurs.
Monitor lizards are covered with large scales. They have strong paws with a tenacious grip and powerful long tail. The animal's tongue is also large in size; at the end it is divided in half. Lizards can only smell with their tongue. The color of animals is dominated by gray and brown shades. Young representatives of the class are often found with spotted or striped scales. Monitor lizards live in regions with warm climates. They are most common in Australia, Africa and southern Asia. Depending on their habitat, monitor lizards are divided into two types. The first of them lives in a desert area with dry trees and shrubs. And the second is located closer to tropical forests and reservoirs. Some representatives of monitor lizards live on tree branches.
Geckos
Unique representatives of reptiles that are able to stick to any surface, even the smoothest. Geckos can climb smooth glass walls, hang from ceilings, and many other interesting things. The lizard is able to stay on the surface with just one paw.
Snakes
These are famous representatives of reptiles. The main difference from other species is the body shape. Snakes have a long body, but do not have paired limbs, eyelids or an external auditory canal. Some of these characteristics are present in individual lizard species, but collectively such characteristics are only observed in snakes.
Zmeinoye the body consists of three elements:
- head;
- body;
- tail.
Some representatives retained rudimentary forms of limbs. A large number of snake species are venomous. They have grooved or channeled teeth that contain venom. This dangerous liquid comes from the animal's salivary glands. All internal organs of a snake differ from standard indicators. They have an oblong shape. Animals do not have a bladder. There is before our eyes cornea, which was formed from fused eyelids. Snakes that are diurnal have a transverse pupil, while nocturnal snakes have a vertical pupil. Because Since animals do not have an auditory canal, they can only hear loud sounds.
Snakes
These are representatives of one of the varieties of snakes. Their main feature is that they are not poisonous. Snakes have bright scales with a large ribbed surface. Animals are common near water bodies. Amphibians and fish serve as food for them. Sometimes snakes manage to catch a bird or small mammal. Such snakes do not kill their prey; they swallow it whole.
If the snake senses danger, it pretends to be dead. And when attacked, a liquid with an extremely unpleasant odor is released from the mouth. Snakes breed on plant soils covered with damp moss or natural debris.
The list of modern reptiles can be continued for a very long time. All representatives of the class have certain similarities characteristic of this type of animal, as well as clear differences. Such animals are of great interest to scientists and hobbyists from all over the world. Their unique features can tell a lot.
The descendants of extinct dinosaurs are numerous reptiles. The list of reptiles includes about ten thousand species. They all breathe through lungs, and their skin is covered with horny scales that protect it from drying out. There are 72 species of reptiles living in our country alone.
The list of reptiles includes about ten thousand species
Class characteristics
The class of reptiles includes a certain group of cold-blooded animals and has a number of anatomical features. The limbs are located on both sides and widely spaced. During movement, the reptile’s body drags along the ground, which does not prevent it from remaining fast and agile in times of danger or hunting.
In prehistoric times, this type of fauna lived in water. In the process of evolution, they switched to a terrestrial existence thanks to cellular lungs, dry body coverings and internal fertilization. During the growth process, the animal sheds periodically.
What they share with fish and amphibians is the body’s ability to regulate body temperature according to environmental conditions. In winter, they lose activity and hibernate. In southern latitudes with a hot climate, many of them are nocturnal. The dense horny cover and the absence of glands in the epidermis prevent moisture loss.
Distribution area
Reptiles are common on all continents except Antarctica. Their populations are especially numerous in tropical and subtropical regions.
The most viable species live on the territory of the Russian Federation. The list of names of reptiles that inhabit almost all regions of our country is quite extensive. It includes:
- - Far Eastern, Mediterranean, leatherback, Caspian, European marsh, bigheaded.
- Lizards- gray and Caspian gecko, motley and long-eared roundhead.
- Snakes- vipers, snakes, copperheads and yellow-bellies.
Reptiles include lizards, snakes, turtles All representatives of this class, living in temperate climates, are not large in size and prefer small areas for living, since they are incapable of long-distance migrations. They are characterized by high fertility. Females lay dozens of eggs. The population density on one hectare can reach one hundred and twenty individuals. Nutritional characteristics play an important role in the biological indication of nature.
Features of reproduction
Reptiles breed on the surface of land. Even those who spend most of their lives in water leave their usual habitat. The mating season is accompanied by increased activity and fights among males. This is especially common in lizards and turtles.
The main part of reptiles are oviparous reptiles. In some species, the egg remains in the oviduct until the baby is fully mature. Such animals belong to ovoviviparous representatives of the fauna.
Reptiles are naturally endowed with a high ability to survive and preserve the species Description of individual species
Reptiles are naturally endowed with a high ability to survive and preserve the species. In the wild, both herbivores and predatory reptiles are found. The list of titles includes:
- turtles;
- crocodiles;
- lizards;
- snake.
There are about three hundred species of turtles. Distributed throughout the world. These harmless animals are often kept as pets. They are among the longest living reptiles. In favorable conditions they live up to two hundred and fifty years.
A strong shell protects them from predators, and their body weight and size depend on their belonging to a particular genus and habitat. Sea turtles can weigh about a ton and have impressive dimensions. Among land species there are tiny specimens weighing 125 grams and a shell length of 10 centimeters.
The animal's head is small, which makes it possible, in case of danger, to quickly remove it under the shell. The reptile has four limbs. The paws of land animals are adapted for digging soil; in marine animals they have turned into flippers.
Crocodiles- the most dangerous reptiles. The names of some species correspond to their habitat. The most famous of them:
- sea or rowing;
- Cuban;
- Mississippian;
- Philippine;
- Chinese;
- Paraguayan.
Crocodiles are divided into the families of gharials, caimans and alligators. They differ from each other in the shape of their jaws and body sizes.
Lizards- quick representatives of fauna. Most of them are small in size and have high regenerative ability. They inhabit different parts of the planet and are well adapted to different climatic latitudes.
The main part of lizards are small in size and have high regenerative ability.
The largest representative of the genus of lizards is komodo dragon. Named after the island of the same name on which it lives. Outwardly it resembles a cross between a dragon and a crocodile. They create a deceptive impression with their clumsiness. However, they are excellent runners and swimmers.
Snakes are included in the list of reptile animals that are missing limbs. Due to the elongated shape of the body, the internal organs acquired an identical structure. More than three hundred pairs of ribs located throughout the body help make flexible movements. The triangular head allows the snake to swallow its prey whole.
There are a huge number of different snakes in nature. Most of them are poisonous. The poison can kill some within a few minutes. Scientists have long learned to use snake venom as medicine and antidotes.
Snakes that lack venomous glands include grass snakes and pythons. The largest snake in the world lives on the banks of the Amazon and is called the anaconda. Kills the victim with the help of powerful muscles, wrapping it in rings.
Due to water pressure, sea snakes lack a rounded shape and resemble a wriggling ribbon. They are very dangerous for humans, as they produce highly toxic poison. Once on land, they die within a few hours. They settle at the mouths of rivers flowing into the sea. They rarely swim far from the shore.
Difference from amphibians
Compared to amphibians, reptiles are better adapted to living on land. Their muscles are well differentiated. This explains their ability to make fast and varied movements.
The digestive system is longer. The jaws are equipped with sharp teeth that help chew even the toughest food. The blood supply is mixed, in which arterial blood predominates. Therefore, they have a higher metabolic rate.
Compared to amphibians, reptiles are better adapted to living on land
The size of the brain relative to the body is larger than that of amphibians. Behavioral characteristics and sensory organs are perfectly adapted to life on the surface of the earth.
Unique reptiles
Among the most interesting and rare reptiles there are those that have anatomical features that are unlike other species. The most remarkable representative of the unique fauna is Hatteria. It lives in only one place - New Zealand. Despite its external resemblance to a lizard, it does not belong to the genus of these reptiles. The internal organs are similar to those of a snake.
Despite its external resemblance to a lizard, tuateria does not belong to the genus of these reptiles
Unlike other animals, it has three eyes, with an additional organ of vision located in the back of the head. Possessing slow breathing, she is capable of not breathing for a minute. The body length is half a meter, weight is about one kilogram.
The topic of this article is reptiles. Species, origin, habitats, as well as some other facts about them will be presented in it.
The word "reptile" comes from a Latin term meaning "to creep" or "to crawl." This implies the nature of movement of representatives of this class. It should be noted, however, that not all reptiles are animals that can only crawl. There are those who jump well, run, swim and even practically fly, gliding like flying squirrels.
Ancient reptiles
These animals lived long before humans appeared on our planet. Reptiles living on Earth today are only relics (minor remnants) of a very diverse and rich class in the past. We are talking about reptiles that reached their greatest prosperity in (approximately 230-67 million years BC). Ancient reptiles were represented in a huge number of forms. Some of their species lived on land. One can note among them the large predatory Tarbosaurus and the giant herbivorous Brontosaurus. Others, such as ichthyosaurs, lived in water. Still others could fly like birds. The amazing world of reptiles of antiquity has not yet been fully studied. Perhaps in the near future scientists will encounter new discoveries.
In 1988, the remains of reptiles were discovered in Scotland. According to experts, these reptiles lived 340 million years ago. It turned out to be the most ancient species of fossil reptile known today. Their body length was only 20.3 cm.
Origin of ancient reptiles
Ancient reptiles evolved from ancient amphibians. This event became the next stage in the adaptation of vertebrates to life on land. Today, amphibians and reptiles coexist. Amphibians are otherwise called amphibians, and reptiles are called reptiles.
Groups of modern reptiles
Reptiles (modern) include the following groups.
1. Crocodiles. These are large animals with a lizard-like body. There are only 23 species, which include true crocodiles, as well as alligators, caimans and gharials.
2. Beakheads. They are represented by only one species of hatteria called Sphenodon punctatus. These reptiles (a photo of one of them is presented below) resemble in appearance (up to 75 cm) with a massive body, five-fingered limbs and large heads.
3. Scaly. This group of reptiles is the most numerous. It includes 7600 species. These include, for example, lizards, the largest group of modern reptiles. These include: monitor lizards, iguanas, lizards, skinks, agamas, chameleons. Lizards are a specialized species that leads a primarily arboreal lifestyle. Scaly animals also include snakes - legless reptiles, as well as amphisbaenas - creatures with a worm-like body and a short tail, externally resembling the head end. Amphisbaenas are adapted to lead a burrowing lifestyle. They very rarely appear on the surface. These reptiles spend most of their lives underground or in the nests of termites and ants, which amphisbaenas feed on. They usually lack limbs. Representatives belonging to the genus Bipes have only front legs. They can move along earthen passages and tail first. Because of this, they are also called two-year-olds. "Amphisbaena" is translated from Greek as "moving in both directions."
4. Another group - turtles. Their bodies are surrounded from below, from the sides and from above by shells. The carapace includes the abdominal (plastron) and dorsal (carapace) shields, which are connected by a bone bridge or tendon ligament. There are about 300 species of turtles.
Together with mammals and birds, reptiles are combined into one group of higher vertebrates.
Where do reptiles live?
Most reptiles lead a terrestrial lifestyle. These are creatures that prefer open landscapes warmed by the sun, including arid deserts practically devoid of vegetation. However, many turtles and all crocodiles live in rivers, lakes or swamps. Some snakes and some turtles also live permanently in the seas.
Reptile skin, unfortunately, is now used for the production of leather products. It is highly valued, and many reptiles suffer because of it. Their future is in our hands.
Habitats of crocodiles
Crocodiles are common in all tropical countries. Basically, these reptiles are animals that live in deep swamps, lakes and rivers. They usually spend most of the day in the water. Crocodiles come out to the coastal shallows in the morning and also in the late afternoon to bask in the sun. Relatively few of their species are tolerant of salty sea water. The saltwater crocodile swims especially far into the open sea - up to 600 km from the coast.
Habitats of tuataria and lizards
Hatterias today survive only on rocky islands located near New Zealand. A special reserve was created here for their sake.
Lizards are distributed almost throughout the planet, except for cold zones. Some types of mountains rise to the border of eternal snow, for example, in the Himalayas - to an altitude of 5.5 km above sea level. Most lizards lead a terrestrial lifestyle.
However, some of them climb trees or bushes, such as roundheads. Others can live permanently in trees and have the ability to glide. Rock-dwelling agamas and geckos can move along vertical surfaces. Also, some lizards live in the soil. They usually have no eyes and their bodies are elongated. The sea lizard lives near the surf line. She has excellent swimming ability. She spends a lot of time in the water, feeding on seaweed.
Where do snakes and turtles live?
Snakes are common everywhere on Earth, except New Zealand, the polar regions and some oceanic islands. They are all good swimmers, and there are even species that spend almost all or all of their time in the water. These are sea snakes. Their tails are compressed laterally in a paddle-like manner. Due to the transition of snakes to a burrowing lifestyle, some of them have smaller eyes and disappeared under the shields, and their tails have also shortened. These are narrow-mouthed snakes and blind snakes.
Freshwater and land turtles are found on many islands, as well as on all continents except Antarctica. Their habitats are very diverse. These are tropical forests, hot deserts, rivers, lakes and swamps, expanses of the ocean and sea coasts. Sea turtles spend their entire lives in water. They come ashore only to lay eggs.
The largest snakes
The largest modern snakes are anacondas (pictured above) and reticulated pythons. They reach 10 meters in length. In Eastern Colombia, a specimen of anaconda was found, unique in size - 11 m 43 cm. The Brahmin blind beetle is a body length of no more than 12 cm.
Sizes of crocodiles
The largest of the crocodiles are the combed and the Nile. They reach a length of 7 m. 1.2 m for females and 1.5 m for males is the maximum body length of the smooth-fronted caiman, the smallest among other species of crocodiles.
The largest and smallest turtles
The largest of the modern turtles is the leatherback sea turtle. Its length can exceed 2 meters. In Great Britain, on the shore in 1988, the dead body of a male was discovered; it had a width of 2.77 m and a length of 2.91. The musk turtle is the smallest of all species. On average, the length of its carapace is 7.6 cm.
Lizard sizes
Among lizards, Virginia round-toed geckos are considered the smallest. The length of their bodies is only 16 mm (excluding the tail). Without a doubt, the largest lizard is the Komodo dragon (its photo is presented below).
The length of its body reaches three or even more meters. The thin-bodied Salvador monitor lizard, which lives in Papua New Guinea, reaches 4.75 m in length, but about 70% of its length is in the tail.
Reptile body temperature
Like amphibians, reptiles do not have any constant body temperature. Their life activity therefore depends to a large extent on the ambient temperature. For example, in dry and warm weather they are especially active and are often seen at this time. On the contrary, in bad weather and cold they become inactive and rarely leave their shelters. At temperatures close to zero, reptiles fall into torpor. That is why they are few in number in the taiga zone. There are only about 5 species here.
Reptiles can control their body temperature simply by taking shelter from hypothermia or overheating. Hibernation, for example, allows reptiles to avoid the cold, and the heat of the day allows them to be active at night.
Breathing Features
Reptiles (photos of some of them are presented in this article), unlike amphibians, breathe only through their lungs. Their lungs retain a sac-like structure, but reptiles have a much more complex internal structure than amphibians. The inner walls of their lung sacs have a folded cellular structure. They resemble a honeycomb. This significantly increases the respiratory surface of reptiles. Unlike amphibians, reptiles do not force air through their mouths. However, most of them are characterized by breathing of the so-called “suction” type. They exhale and inhale air through the nostrils by constricting and expanding the chest. The act of breathing is carried out using the abdominal and intercostal muscles.
However, in turtles, the ribs are immobile due to the presence of a shell, so the species belonging to them have developed a different method of ventilation than other reptiles. They force air into their lungs by swallowing it or by making pumping movements with their front legs.
Reproduction
Reptiles breed on land. Moreover, unlike amphibians, they have direct development, that is, without a larval stage. Reptiles usually lay large, yolk-rich eggs with shell and amniotic (embryonic) membranes, which protect the embryos from mechanical damage and water loss, and also provide gas exchange and nutrition. By the time of hatching, young reptiles reach significant sizes. These are already miniature copies of adult individuals.
The class Reptiles (reptiles) includes about 9,000 living species, which are divided into four orders: Squamate, Crocodiles, Turtles, Beaked. The latter is represented by only one relict species - hatteria. Scaly animals include lizards (including chameleons) and snakes.
The sand lizard is often found in central RussiaGeneral characteristics of reptiles
Reptiles are considered the first true terrestrial animals, since their development is not associated with the aquatic environment. Even if they live in water (aquatic turtles, crocodiles), they breathe with their lungs and come to land to reproduce.
Reptiles are distributed over land much more widely than amphibians and occupy more diverse ecological niches. However, due to their cold-blooded nature, they predominate in warm climates. However, they can live in dry places.
Reptiles appeared from stegocephalians (an extinct group of amphibians) at the end of the Carboniferous period of the Paleozoic era. Turtles appeared earlier, and snakes appeared later than everyone else.
The heyday of reptiles occurred in the Mesozoic era. At this time, various dinosaurs lived on Earth. Among them were not only terrestrial and aquatic species, but also flying ones. Dinosaurs went extinct at the end of the Cretaceous period.
Unlike amphibians, reptiles
improved head mobility due to a larger number of cervical vertebrae and a different principle of their connection to the skull;
the skin is covered with horny scales that protect the body from drying out;
breathing is only pulmonary; the chest is formed, which provides a more advanced breathing mechanism;
although the heart remains three-chambered, the venous and arterial blood flows are better separated than in amphibians;
pelvic kidneys appear as excretory organs (and not the trunk ones as in amphibians); such kidneys retain water in the body better;
the cerebellum is larger than that of amphibians; the volume of the forebrain is increased; the rudiment of the cerebral cortex appears;
internal fertilization; reptiles reproduce on land mainly by laying eggs (some are viviparous or ovoviviparous);
embryonic membranes (amnion and allantois) appear.
Reptile skin
The skin of reptiles consists of a multilayer epidermis and connective tissue dermis. The upper layers of the epidermis become keratinized, forming scales and scutes. The main purpose of scales is to protect the body from water loss. In general, the skin is thicker than that of amphibians.
The scales of reptiles are not homologous to the scales of fish. Horny scales are formed by the epidermis, i.e., they are of ectodermal origin. In fish, scales are formed by the dermis, that is, they are of mesodermal origin.
Unlike amphibians, there are no mucous glands in the skin of reptiles, which is why their skin is dry. There are only a few scent glands.
In turtles, a bony shell is formed on the surface of the body (top and bottom).
Claws appear on the fingers.
Since keratinized skin inhibits growth, reptiles are characterized by molting. At the same time, the old integument moves away from the body.
The skin of reptiles grows tightly together with the body, without forming lymphatic sacs, like in amphibians.
Reptile skeleton
In comparison with amphibians, the spine of reptiles is no longer divided into four, but five sections, since the trunk section is divided into thoracic and lumbar.
In lizards, the cervical region consists of eight vertebrae (different species have from 7 to 10). The first cervical vertebra (atlas) is like a ring. The odontoid process of the second cervical vertebra (epistrophy) enters it. As a result, the first vertebra can rotate relatively freely around the process of the second vertebra. This gives greater head mobility. In addition, the first cervical vertebra is connected to the skull by one mouse, and not two like in amphibians.
All thoracic and lumbar vertebrae have ribs. In lizards, the ribs of the first five vertebrae are attached to the sternum by cartilage. The chest is formed. The ribs of the posterior thoracic and lumbar vertebrae are not connected to the sternum. However, snakes do not have a sternum and therefore do not form a rib cage. This structure is associated with the characteristics of their movement.
The sacral spine in reptiles consists of two vertebrae (and not one, as in amphibians). The iliac bones of the pelvic girdle are attached to them.
In turtles, the vertebrae of the body are fused with the dorsal shield of the shell.
The position of the limbs relative to the body is on the sides. Snakes and legless lizards have reduced limbs.
Digestive system of reptiles
The digestive system of reptiles is similar to that of amphibians.
The oral cavity contains a movable, muscular tongue, which in many species is forked at the end. Reptiles are able to throw it far.
In herbivorous species, a cecum appears. However, most are predators. For example, lizards eat insects.
The salivary glands contain enzymes.
Respiratory system of reptiles
Reptiles breathe only with their lungs, since due to keratinization the skin cannot take part in respiration.
The lungs are improved, their walls form numerous partitions. This structure increases the inner surface of the lungs. The trachea is long, at the end it is divided into two bronchi. In reptiles, the bronchi in the lungs do not branch.
Snakes have only one lung (the right one, and the left one is reduced).
The mechanism of inhalation and exhalation in reptiles is fundamentally different from that of amphibians. Inhalation occurs when the chest expands due to stretching of the intercostal and abdominal muscles. At the same time, air is sucked into the lungs. When you exhale, the muscles contract and air is pushed out of the lungs.
Circulatory system of reptiles
The heart of the vast majority of reptiles remains three-chambered (two atria, one ventricle), and arterial and venous blood are still partially mixed. But compared to amphibians, in reptiles the venous and arterial blood flows are better separated, and, therefore, the blood mixes less. There is an incomplete septum in the ventricle of the heart.
Reptiles (like amphibians and fish) remain cold-blooded animals.
In crocodiles, the ventricle of the heart has a complete septum, and thus two ventricles are formed (its heart becomes four-chambered). However, blood can still mix through the aortic arch.
Three vessels independently depart from the ventricle of the heart of reptiles:
It departs from the right (venous) part of the ventricle common trunk pulmonary arteries, which further divides into two pulmonary arteries leading to the lungs, where the blood is enriched with oxygen and returns through the pulmonary veins to the left atrium.
Two aortic arches extend from the left (arterial) part of the ventricle. One aortic arch begins to the left (however called right aortic arch, as it bends to the right) and carries almost pure arterial blood. From the right aortic arch originate the carotid arteries leading to the head, as well as the vessels supplying the girdle of the forelimbs with blood. Thus, these parts of the body are supplied with almost pure arterial blood.
The second aortic arch extends not so much from the left side of the ventricle, but from its middle, where the blood is mixed. This arch is located to the right of the right aortic arch, but is called left aortic arch, since at the exit it bends to the left. Both arches of the aorta (right and left) on the dorsal side are connected into a single dorsal aorta, the branches of which supply mixed blood to the organs of the body. Venous blood flowing from the organs of the body enters the right atrium.
Excretory system of reptiles
In reptiles, during embryonic development, the trunk kidneys are replaced by pelvic ones. The pelvic kidneys have long nephron tubules. Their cells are differentiated. Reabsorption of water occurs in the tubules (up to 95%).
The main excretion product of reptiles is uric acid. It is almost insoluble in water, so the urine is mushy.
The ureters extend from the kidneys and empty into the bladder, which opens into the cloaca. In crocodiles and snakes, the bladder is underdeveloped.
Nervous system and sensory organs of reptiles
The brain of reptiles is being improved. In the forebrain, the cerebral cortex appears from the gray medulla.
In a number of species, the diencephalon forms the parietal organ (third eye), which is capable of perceiving light.
The cerebellum in reptiles is better developed than in amphibians. This is due to the more diverse motor activity of reptiles.
Conditioned reflexes are difficult to develop. The basis of behavior is instincts (complexes of unconditioned reflexes).
The eyes are equipped with eyelids. There is a third eyelid - the nictitating membrane. Snakes have transparent eyelids that grow together.
A number of snakes have pits at the front end of their heads that receive thermal radiation. They are good at determining the difference between the temperatures of surrounding objects.
The organ of hearing forms the inner and middle ear.
The sense of smell is well developed. There is a special organ in the oral cavity that distinguishes odors. Therefore, many reptiles stick out their tongue, forked at the end, taking air samples.
Reproduction and development of reptiles
All reptiles are characterized by internal fertilization.
Most lay eggs in the ground. There is a so-called ovoviviparity, when the eggs are retained in the female’s genital tract, and when they emerge from them, the young hatch immediately. In sea snakes, true viviparity is observed, with the embryos developing a placenta similar to the placenta of mammals.
Development is direct, a young animal appears, similar in structure to the adult (but with an underdeveloped reproductive system). This is due to the presence of a large supply of nutrients in the yolk of the egg.
In the eggs of reptiles, two embryonic membranes are formed, which are not present in the eggs of amphibians. This amnion And allantois. The embryo is surrounded by an amnion filled with amniotic fluid. The allantois is formed as an outgrowth of the posterior end of the intestine of the embryo and performs the functions of the bladder and respiratory organ. The outer wall of the allantois is adjacent to the egg shell and contains capillaries through which gas exchange occurs.
Caring for the offspring of reptiles is rare; it consists mainly of protecting the masonry.
Reptiles or reptiles are the oldest class of true vertebrates that settled on land.
Reptiles include various types of snakes, crocodiles, turtles and lizards.
They were the largest representatives of the dinosaurs that dominated the Earth 150 million years ago.
The animals are direct ancestors despite the fact that they now live in swamps - some of them could fly, and their elongated scales eventually turned into feathers.
Description
The name of the class comes from the word to creep - to move by crawling, dragging your stomach along the ground. This is true - reptiles have no limbs at all; in others they are located almost at the level of the spine.
Appearance
Unlike amphibians, which are wet and slippery to the touch, reptiles have always dry skin. This helps retain moisture inside the body, which is especially important for inhabitants of arid areas.
Reptiles description
Reptiles are endowed with perfectly protected skin from external influences, including the scorching sun; the skin is covered with scales. Snakes and lizards periodically molt, that is, shed the skin from which they grew, and then grow new skin.
Almost all animals of the reptile class are colored in accordance with the color scheme of the environment, so as not to become easy prey for predators, and so as not to be too noticeable to their victims.
The chameleon became famous for the fact that it can change color depending on many factors - temperature, humidity, thirst, emotional state.
Nutrition
Animals are not able to chew food, they can only tear it into pieces. And snakes generally swallow prey whole, and often the size of the victim exceeds the size of the snake itself.
Reptiles of our Planet
A snake can perform such a trick thanks to its ability to open its mouth very wide; its stomach can stretch to incredible sizes.
Habitat
Most reptiles live in warm regions - deserts, semi-deserts and tropical rainforests.
They can also be found in cooler natural zones, in deciduous and mixed forests, but much less frequently.
Unusual reptiles
This is explained by the fact that the body temperature of reptiles is practically no different from the ambient temperature. Therefore, reptiles living in cold areas have to warm up in the sun for a long time. In the warm season they lead an active life, and in the cold season they hibernate.
Reproduction
Reptiles lay eggs in a hard protective shell and leave them in nests or simply bury them in the sand.
All of them, with the exception of , do not care about the future fate of their cubs - having hatched from the eggs, they already lead an independent life. Some species of lizards and snakes are viviparous.
Red Book
Almost all species of reptiles are listed in the Red Book, some of them are on the verge of extinction.
Reptiles animals snakes photo
On the part of the governments of some countries, measures are being taken, special farms are being created for the reproduction of one or another species that is about to disappear. But this will not help much, since many species of reptiles have already been so exterminated by humans that it is not possible to restore them.
Lifespan
Due to the fact that all processes in the body of reptiles occur very slowly, their life expectancy is very high. Crocodiles live about 70 years, and turtles live more than 150.
- Reptiles are an important link in the food chain - they feed on insects and small rodents and, thereby, regulate their numbers. The reptiles themselves serve as food for some.
- Snake venom is the basis of many medicines.
- Expensive shoes and accessories are made from crocodile and snake skin, and jewelry is made from shells.
- For this purpose, reptiles are raised on special farms so as not to reduce their numbers in the wild.
- The meat and eggs of crocodiles and turtles are eaten by residents of many tropical countries.
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