Where do reptiles lay eggs? Class reptiles or reptiles
Reptile eggs are similar in structure to birds' eggs. On the outside, they are covered with a leathery shell, on the surface of which, in some groups, lime may be deposited. This occurs in crocodiles and some turtles. In lizards, the egg shell is always leathery.
The presence of a dense leathery and calcareous shell in reptile eggs is due to the fact that their development occurs on land. And on land, humidity is very low - only 3-15%, so the developing embryo needs protection to prevent water loss. The calcareous shells of crocodiles and some turtles are especially good at preventing eggs from drying out.
Inside a reptile's egg, just like a bird's, there is a yolk surrounded by a layer of protein. This is the stock nutrients for the developing embryo.
Shape and size of reptile eggs?
I teach a lesson about reptile eggs with children at the Oceanarium museum (Vladivostok). At the live exhibition we can observe Nile crocodile and the common iguana. And also turtles: Chinese trionix and red-eared.
Reptile eggs, video about Chinese Trionix:
This short video introduced you to the Chinese Trionics, the development of which will be discussed below.
It so happened that the topic “development of reptiles” fell on the day of the celebration Orthodox Easter. Therefore, we considered the egg as a symbol of life and carried out a kind of research.
I asked the guys to compare the shape and size of the eggs of reptiles known to us and some fish, also presented at the live and “dry” exhibitions of the Oceanarium museum.
Study of the shape and size of eggs of reptiles and fish
Each study participant received a form with a life-size outline of the eggs of the studied animal species.
In progress collective discussion We completed the task and wrote the number of the animal’s name next to the outline of the egg.
"Portrait" of a Nile crocodile
Then we went to the museum exposition and already on the spot next to the terrariums and aquariums the guys heard brief information about the characteristics of reproduction and development of each animal.
For example, the Nile crocodile begins to reproduce at the age of 10 years. The female lays eggs in a nest, which she builds from plant debris, and then fills the nest with sand. The entire time the eggs are incubating, which is about three months, she does not leave the nest. There are an average of 40-60 eggs in a clutch. And the surprising thing is that they are very similar in shape and size to chickens. The shell of the Nile crocodile egg is calcareous.
Nile crocodiles are caring parents!
Female Nile crocodiles Very caring mothers. As soon as they hear grunting sounds from the nest, they begin to dig out the eggs and help the hatchlings free themselves from the shell. Female She has already chosen a shallow body of water in advance, into which she transfers her cubs immediately after their “birth”. Often she collects them in her mouth and carries them in her mouth. The crocodiles remain in this reservoir under the supervision of their mother for another 1.5–2 months. Video about a female Nile crocodile
The father Nile crocodile usually helps the female guard the nest, and sometimes the growing children, while they are in a kind of “nursery” - a shallow body of water into which their mother transferred them.
Turtles don't care about their young
But turtles don’t care about their offspring at all. For example, Chinese trionix (Far Eastern soft-shelled turtle, Chinese leatherback turtle).
Chinese Trionix
Trionyx females lay their eggs on sandbanks or pebbles close to the water. The nesting hole is usually located at a depth of 15-20 cm. The shape of the eggs is spherical, the color is yellowish or slightly beige. The diameter of the egg is approximately 2 cm.
One female makes 2-3 clutches during the breeding season. The total number of eggs laid is from 18 to 75. Why is there such a spread? Clutches of large old Chinese Trionyx females have more eggs than young ones.
40-60 days after the eggs are laid, the turtles hatch and immediately head to the water. The length of their shell is only 3 cm. Therefore, they travel 15-20 m to the water in 40-45 minutes. Of course it takes a long time. In saving water, they immediately hide under stones or burrow into the ground.
The common iguana is not a caring mother!
And another example of “bad” motherhood from the world of reptiles. Wikipedia gives detailed information about the reproduction of the common or green iguana.
This type of iguana digs its nest on dry sand dunes. The depth of the nest indicates its reliability - 45-100 cm. The female iguana lays many eggs - up to 70, so this process of laying eggs takes several days (up to three or more).
Egg shell common iguana soft leathery, but quite durable. Eggs white oval shape, with a diameter of about 1.5 cm and a length of about 3.5-4.0 cm.
After laying eggs, having carefully buried the hole, the lizard never returns to this place.
Interesting fact: several iguanas can lay eggs in one hole if there are few suitable places for laying eggs.
Conclusion
So, let’s summarize some of the article on the reproduction and development of reptiles:
- Using the example of studying the shape of reptile eggs, you saw how a simple task helps children focus their attention on the museum exhibit object you have chosen.
- A brief summary of information on the reproduction, development and care of offspring in reptiles: Chinese trionix, Nile crocodile, and common iguana is provided.
The next article will be about fish reproduction and will introduce you to the largest fish eggs. We will once again turn to the form depicting the outlines of eggs.
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Anatomy, morphology and ecology of reptiles
9. Genital organs and reproduction of reptiles
The gonads lie in the body cavity on the sides of the spine. Testes - paired oval bodies. Through the appendages, which represent the preserved part of the trunk kidney (mesonephros) and contain numerous tubules, the testes are connected to deferent ducts , which serve as the ducts of the mesonephric kidney, i.e. Wolffian canals. The right and left vas deferens open into the corresponding ureters at their confluence with the cloaca.
One of the adaptations to terrestrial existence is internal fertilization. In this regard, the males of all reptiles, except the hatteria, have special copulatory organs ; in crocodiles and turtles it is unpaired, and in lizards and snakes it is paired outgrowths of the posterior wall of the cloaca, which turn outward during fertilization (Fig. 14).
Rice. 14. Protruding copulatory sacs of a male lizard
Doubles ovaries have the appearance of granular oval bodies. Oviducts Müllerian canals serve. They begin flickering funnels , located near the ovaries, and open into the cloaca.
Fertilization occurs in the upper part of the oviduct. The secretions of the secretory glands of the middle part of the oviduct form around eggs(yolk) protein coat , weakly developed in snakes and lizards, and powerful in turtles and crocodiles (Fig. 15).
Rice. 15. Scheme of development of egg membranes in the Central Asian turtle as the egg passes through the oviduct: 1 - egg, 2 - albumen, 3 - fibrous membrane, 4 - shell membrane
Outer membranes are formed from the secretion secreted by the cells of the walls of the lower part of the oviduct (uterus).
Embryonic development follows a typical path for amniotes. Are formed embryonic membranes - serosa and amnion - allantois develops. In lizards and snakes, water necessary for the formation of amniotic fluid and for the normal development of the embryo is obtained through the oxidation of fats yolk(metabolic water) and absorption of moisture from the external environment, and in turtles and crocodiles with dense shells - due to metabolic water and the supply of water in a powerful protein coat. The minimum soil moisture at which eggs with a fibrous shell can develop normally is about 2.5%, and if there is a shell - even up to 1%. Different types lay eggs in soil of a certain moisture content, corresponding to the properties of the egg shells and the needs of the developing embryo.
Most reptiles bury their eggs into the ground in well-heated places; Some species lay eggs in heaps of plant debris or under rotting stumps, using the heat generated during decay. Some crocodiles dig holes and cover the eggs with plant debris; females stay near the nest and guard the clutch. Protected masonry and some large lizards(monitor lizards, etc.). Female pythons wrap their bodies around the clutch of eggs, not only protecting it, but also warming it: in such a “nest” the temperature is 6-12 ° C higher than the environment. In crocodiles, the female guarding the nest digs up the clutch when the young hatch, making it easier for them to come to the surface; in some species, females guard the young and at first independent life. The females of some skinks and spindles also do not leave the clutches, protecting them from enemies.
In a relatively small number of species of modern squamates (order Squamata) there is ovoviviparity or less often live birth. The common viper - Vipera berus, viviparous lizard - Lacerta vivipara, spindle - Anguis fragilis have fertilized eggs delayed in the female genital tract, passing through all stages of development there; the embryos hatch immediately after the eggs are laid.
Ovoviviparity also characteristic of sand boas - Erukh, sea snakes, some snakes and lizards. Ovoviviparity developed from cases of temporary retention of eggs in the oviducts noted for a number of species of lizards and snakes. Thus, in common grass snakes - Natrix natrix, the duration of egg development is external environment can range from 30-60 days depending on how long they were in the mother’s body. Some species switch to ovoviviparity only under certain conditions. The Tibetan roundhead - Phrynocephalus theobaldi lays eggs at an altitude of 2-3 thousand m above sea level, and above (4-5 thousand m) it is ovoviviparous. The viviparous lizard - Lacerta vivipara in the south of its range (France) lays eggs, and its northern populations are ovoviviparous.
True live birth known in some skinks (Chaleides, Lygosoma, Taliqua). They lack the outer shell of eggs, the embryonic membranes of the developing embryo adjoin to the walls of the uterine section of the oviduct; By osmosis and diffusion, oxygen and nutrients from the mother's bloodstream enter the embryo's circulatory system. Some snakes (Thamnophis sirtalis, etc.) and lizards develop a real placenta: outgrowths of the serous membrane and allantois of the embryo are introduced into the mucous membrane of the uterine section of the mother’s oviduct. Due to the close proximity of the blood vessels of the female and the embryo, the supply of oxygen and nutrients to the embryo is facilitated. Development in the mother's body provides better temperature conditions for embryogenesis, and therefore both forms of viviparity predominate in the north and in the mountains. Viviparity is sometimes associated with an arboreal and aquatic lifestyle: some chameleons and aquatic snakes have it.
Puberty occurs at different times: in crocodiles and many turtles at six or ten years of age, in snakes more often in the third to fifth year of life, in large lizards in the second or third year, and in small ones in the ninth to tenth month of life.
Fertility reptiles are much lower than the fertility of amphibians. Its decrease is associated with a reduction in embryonic mortality due to the sheltered placement of clutches, and in a few species - their protection and ovoviviparity. Important role plays and direct development, without metamorphosis and change of habitats; the latter is always accompanied by high mortality. The high mobility of hatched cubs and their secretive lifestyle also reduces the death. The clutch size rarely exceeds one hundred eggs (some crocodiles, large turtles and snakes); more often it is limited to 20-30 eggs. Small species of lizards lay only 1-2 eggs, but several times a season.
In some lizards (Caucasian rock lizards - Lacerta armenica, Lacerta dahli, Lacerta rostombecovi, North American teiids - Cnemidophorus, possibly in some agamas and in the gecko - Hemidaetylus turcicus) it is established or assumed parthenogenetic reproduction, i.e., the development of laid unfertilized eggs (I. S. Darevsky). Populations of such species consist only from females. Parthenogenesis in lizards is usually observed in peripheral populations, i.e. at the boundaries of the range. In such a situation, the existence of a same-sex population of only females becomes advantage, since it allows limited supplies feed is spent most efficiently only on young-producing individuals. This can be supported natural selection, but represents a dead end in evolution, because it excludes panmixia and the associated recombination of genes, which sharply limits variability.
Finally, a surprising case has been discovered in snakes hermaphroditism(bisexuality, or intersexuality). The snake, the island bothrops Bothrops insularis, lives only on the island. Queimada Grande is only 3 km in area (60 km from Santos in Southern Brazil), most females simultaneously with the ovaries have male copulatory organs and fully developed testes. Apparently, in a small island population, such intersexuality makes it possible to increase the rate of reproduction without increasing the number of inhabitants. It has been noticed that over the past 50 years the proportion of males in the population has decreased.
At the Ecosystem Ecological Center you can purchase color identification table " Amphibians and reptiles of central Russia"and a computer identification of reptiles (reptiles) of Russia and the USSR, as well as others teaching materials on animals and plants of Russia(see below).
On our website you can also find information on anatomy, morphology and ecology of reptiles:
Reptiles are dioecious and may differ in secondary sexual characteristics. Often these differences are minor or even non-existent. Sometimes males are only larger than females, as is usually the case with species of the genus Lacerta, with the exception of the viviparous lizard (Lacerta vivipara), where the female is larger, which is associated with the development of young in the body. Same thing with viviparous snakes. The males of many species of lizards, snakes and turtles have a swollen tail at the base. This depends on the fact that the double copulatory member is in a collapsed state. In turtles, the sexes can be distinguished by the appearance of the chest shield - in males it is concave, while in females it is flat or convex. In other cases the meaning of secondary sex differences is unclear; for example, the difference in the number of scutes in many snakes, the greater narrowness of the neck. Many female snakes have keeled ridges on their dorsal scales during sexual activity. This sign serves to irritate the female during mating.
The meaning of the differences in color observed in some reptiles is not clear. For example, male Cistudo turtles have red eyes, while females have brown eyes. In the bloodsucker (Calotes versicolor), the body color of the male can change at will. Sometimes it is all brilliant red with black spots; in some cases, the skin color changes only on the head, in others - on the entire body, not excluding the tail. The female remains monochromatic. However, bright colors are not always associated with gender. The sexes may further differ in the presence of numerous projections on the head, for example in some species of chameleon, where the male develops horns similar to those of a rhinoceros. This also includes the ridges on the back of the head and on the back of many iguanas. The so-called femoral pores in male lizards are more highly developed. In some reptiles, males also differ in their voice, and it is possible that it serves to attract females. In geckos and alligators, the voice definitely serves to attract females during the breeding season.
The ratio of the number of individuals of both sexes is not always the same. In snakes it is 1:1, 1:3, 1:4, 4:11. Sometimes the same species has different sex ratios in different areas. Thus, the Chinese form Dinodon septentrionale throughout its habitat gives the numbers 3:13, and in South Asia - 0:8. The smaller number of males is apparently due to the higher mortality of the latter.
On the other hand, sometimes there is a temporary predominance of males. Thus, in Central Asia at the end of summer (August) only male snakes are found, while females are absent and it is unknown where they are at this time.
During the mating period, fighting often occurs between males. Crocodiles ferociously chase each other at this time and get into fights. The same thing is observed in lizards; some of them change color during a fight. During the breeding season, snakes gather in large numbers, curl into balls and hiss until they connect with the female, after which sexual arousal subsides.
In reptiles, during the mating season, love games. Male lizards bite females to force them to mate; the same thing was sometimes observed in turtles, where the males emit a whistling tone, crawl behind the female, bite her on the head and push her until she becomes excited. After mating, the excitement disappears and the individuals disperse. Only rarely is a male and female staying together for a long time. The turtle Testudo polyphemus was observed to live in pairs in burrows. There are several other similar examples.
Most reptiles lay eggs, while others give birth to live young. Eggs are covered with a hard or parchment-like shell. The first state, typical of turtles, is apparently more primitive. Among lizards, shelled eggs are found only in geckos. But their shell hardens only gradually, absorbing carbon dioxide from the air. In snakes, eggs with shells are no longer found. When most snakes lay eggs, they are sticky and stick to objects they come into contact with. They often vary both in size and shape.
The number of eggs is from 2 to 150. Both the number of eggs and the method of reproduction show signs of adaptation to the conditions of the outside world and are determined by them. The largest (up to 400 per year) egg production is observed in sea turtles. This is apparently due to the fact that young turtles are poorly adapted to life in water at first: they swim, but do not dive, are thrown ashore and serve as prey for fish and birds. Excessive increase in body weight from such a mass of eggs and excessive need for nutritional material are avoided by laying eggs in batches and losing the shell. A very small number of eggs can also be considered an adaptive phenomenon. Turtles that breed in China in cultivated areas where animal enemies are almost entirely absent lay a minimal number of eggs (2). Geckos lay more eggs in the south of Asia than in the north, which can be attributed to the presence of their enemy tree snake - Chrisopelea ornata. Climbing forms lay fewer eggs than terrestrial ones.
Eggs are laid either in specially dug holes, or among moss and foliage, in damp warm places. The US snake Diodophys punctatus lays its faces in a variety of places: in dirt thrown out of a quarry, in dust under a rotten tree, in a stump, under a stone, in the passages of ants with dust - generally in damp, but not wet places exposed to the sun. In 95% of cases it is a hole in the ground. Usually the female leaves the eggs to their fate. Only some snakes and crocodiles behave differently; some American forms of the latter make real nests for their eggs in damp places. This nest consists of a layer of plants on which eggs are laid, again then covered with plants. Due to the rotting of plants in the nest, such heat that the nest is smoking. This warmth serves for the rapid development of the young.
In Madagascar, a female crocodile guards the nest until the young develop. The female allegedly recognizes this by the special sound that young crocodiles make in the egg, helps them dig out of the sand and immediately leads them to the water. The female caiman behaves the same way. African crocodiles do not appear to guard their nests. North American alligators lay a nest near the habitat of the female, who rushes at everyone who approaches her, and in this way guards the nest. Here we have an interesting series of gradual complication of instinct, showing how it could arise. As stated in the systematic part, dinosaurs laid eggs in nests.
Some females large snakes(pythons, for example), having laid eggs, lie on them in such a way that they form a flat arch above them, inside which the temperature is 10-12° Celsius higher than the surrounding one, which promotes the development of eggs. The copperhead Ancistrodon does the same. At this time, the female does not take any water or food and protects the eggs from any attack on them. This can also be seen as caring for the offspring. A lizard called teyu (Tupinambis teguixin) excavates termite nests and lays its eggs there. Young lizards emerging from the latter immediately find food in the form of termites.
Many reptiles give birth to live young and are viviparous. The cubs break through the thin membranes of the eggs while still in the mother’s body or immediately after birth. It is more correct to call them not viviparous, but ovoviviparous. Ovoviviparous forms are not known only in crocodiles and turtles. We find this type of reproduction in many lizards, especially those living in the mountains, in many gigantic American snakes, sea snakes, vipers, various snakes and others. Only in a few reptiles do we find true viviparity, when the nutrition of the embryo in the mother’s body occurs with the help of blood vessels the yolk sac, which comes into contact with the vessels of that section of the oviduct, which plays the role of the uterus. Fossil ichthyosaurs (Ichtyosauria) were also viviparous. This feature stood out to them, like sea snakes, in connection with the transition to pelagic life in the sea. Based on the structure of the limbs of ichthyosaurs, it can be judged that ichthyosaurs never came ashore, but led a life similar to the life of modern whales.
The primary form of reproduction in reptiles is reproduction by laying eggs. From it a series of transitions leads to ovoviviparity and further to viviparity. This transition is facilitated in reptiles by the fact that when circumstances unfavorable for the laying of eggs occur, the latter can be delayed for weeks and the egg remains in the body. The conditions under which viviparity arose in reptiles as an adaptation to them can be named as follows: a) purely aquatic life(Hydrophis); in species of large oviparous genera (Natrix, Elaphe) that transition to life in water (Natrix annularis, Elaphe rufodorsata), viviparity develops; b) distribution in cold areas, at the cold boundaries of their vertical and horizontal range, where night temperatures are too low for eggs and require protection in the mother's body (Phrynocephalus from the Central Asian highlands, Lacerta vivipara, Vipera herus, Ancistrodon in Asia). Living in Tibet at an altitude of 4,200 m but near hot springs, the Natrix species lays eggs; c) life underground (Scincus officinalis, Echis carinata, Vipera ammodytes); d) life on trees and shrubs (Dryophis, Boiga). If any group of reptiles has lived since ancient geological times in conditions that cause viviparity, then the latter is characteristic of all members of the group. Thus, in Scincidae, the skinks, viviparity is a characteristic of the entire group.
The duration of incubation varies among reptiles. It depends on the conditions in which the eggs develop; On average, snakes last between 2 and 3 months. Hatching from an egg can take many hours, up to a day. Not all eggs hatch at the same time. It takes 2-3 days for snakes to emerge from all eggs in a clutch.
Having emerged from the egg or being born alive, reptiles grow quickly but reach sexual maturity very slowly: for example, the Chinese snake (Natrix piscator) in the 4th year, the tree snake (Dryophis) at the end of the 2nd year, male pythons at the end 3rd and females - 4th year. But reptiles reach a very old age. Regarding turtles, for example, there are cases where they survived in captivity for up to 54 years. The giant tortoise (Testudo sunieri) reached the age of 150 years in captivity. There are cases where turtles lived up to 250 years. Great age crocodiles also reach. Reptiles are apparently little susceptible to diseases, although parasites of the protozoa type are often found in the blood of reptiles. It must be assumed that in a natural environment, most reptiles die not from old age and disease, but from a violent death or from some external unfavorable causes. However, there is a suspicion that lizards are carriers and transmitters of certain diseases (for example, leishmaniasis).
Task 1. Write what explains the more complex structure respiratory system reptiles compared to amphibians.
The emergence of air respiratory organs in chordates occurred more than once and was often only idioadaptations and did not lead to noticeable biological progress. Example - lungfish, as an adaptation to life in frequently drying up reservoirs; amphibians have adapted to breathing dry air, i.e. developed a way to avoid drying out of the lungs (bronchi). This is all idio-adaptation.
Task 2. Write down the numbers of the correct statements.
Statements:
1. The shell of a reptile egg protects the embryo from drying out.
2. The respiratory surface of the lizard's lungs is larger than that of the newt.
3. All reptiles have a three-chambered heart.
4. The body temperature of reptiles depends on the ambient temperature.
5. All reptiles lay eggs on land.
6. In reptiles living in northern regions Live births are more common.
7. Mixed blood flows in the ventricle of a lizard’s heart.
8. There is no diencephalon in the brain of reptiles.
9. Viviparous lizards do not produce eggs.
10. In sea turtles, salts are removed from the body through special glands.
Correct statements: 1, 2, 4, 6, 9, 10.
Task 3. Color internal organs lizards (in red - circulatory organs, green - organs of the digestive system, blue - respiratory organs, brown - excretory organs, black - reproduction) and label them.
1. Excretory organs: 1) kidney; 2) bladder; 3) cloaca.
2. Reproductive organs: 1) testes; 2) vas deferens.
3. Digestive system: 1) mouth; 2) nostrils; 3) oral cavity; 4) pharynx; 5) esophagus; 6) trachea; 7) lung; 8) liver; 9) stomach; 10) pancreas; 11) small intestine; 12) large intestine; 13) cloaca.
4. Circulatory system: 1) heart; 2) carotid artery; 3) aorta; 4) pulmonary artery; 5) vein; 6) intestinal vein; 7) pulmonary vein; 8) capillary network.
Task 4. Fill out the table.
Comparative characteristics Comparable characteristic Class Amphibians Reptiles Coverings of the body smooth thin skin rich in skin glands keratinized dry skin forms scales Skeleton torso, skull, limbs, spine (4 sections) skull, torso, limbs, spine (5 sections) Organs of locomotion limbs limbs Respiratory system skin and lungs lungs Nervous system brain and spinal cord brain and spinal cord Sense organs eyes, ears, tongue, skin, lateral line eyes, ears, nose, tongue, sensory cells of touch. hair.
Task 5. The structure of the reproductive organs of amphibians and reptiles is not significantly different. However, amphibians typically lay thousands of eggs, many times more than reptiles. Give reasons for this fact.
Reptiles have internal fertilization. Reptiles lay eggs, from which developed young hatch. The eggs of reptiles are better protected, which means they have a better chance of surviving in this world. And in amphibious organisms, fertilization occurs in water (i.e., external fertilization). Amphibians lay eggs, from which larvae hatch, which then become young. Eggs, that is, eggs, of amphibians do not have a hard protective shell, so there are predators that eat amphibian eggs. That's why amphibians lay a lot of eggs, because most of the eggs (larvae) will die.
They explored new, drier habitats. Reptiles gained an advantage in the struggle for existence due to the emergence of adaptations to prevent the loss of water by the body and the transition to a terrestrial method of reproduction.
Having conquered the land, the ancient reptilians reached an unprecedented peak. In the Mesozoic they were represented by a huge variety of forms.
The class Reptiles, or Reptiles, is represented primarily by terrestrial animals. They reproduce and develop exclusively on land. Even those species that live in water breathe atmospheric air and go ashore to lay eggs.
The body of reptiles consists of a head, torso and tail. It is protected from drying out by the skin. Breathing is exclusively pulmonary. The more complex structure of the circulatory system allowed reptiles to more successfully adapt to the conditions of the land-air habitat compared to amphibians. Reptiles are cold-blooded animals, their activity depends on the ambient temperature, so most species live in areas with a hot climate.
Many species of reptiles have elongated bodies, for example snakes, lizards, and crocodiles. In turtles it is round and convex. Reptiles have dry skin without glands. She's covered horny scales, or shields, and almost does not participate in gas exchange. As reptiles grow, they periodically shed their skin. Reptiles have two pairs of legs on the sides of their body. The exceptions are snakes and legless lizards. The eyes of reptiles are protected by eyelids and a nictitating membrane (third eyelid).
Respiratory system
Due to the loss of skin respiration, the lungs of reptiles are well developed and have a cellular structure. The rib cage is formed for the first time in the skeleton. It consists of the thoracic spine, ribs and sternum (absent in snakes). Volume chest can change, so reptiles breathe by sucking air into their lungs, and not swallowing it, like amphibians.
Nervous system
The brain of reptiles is larger and has a more complex structure than that of amphibians: the size of the cerebellum and cerebral hemispheres has increased. This is associated with their better coordination, mobility, and development of sensory organs, especially vision and smell.
Nutrition and excretion
Most reptiles are predators, only land and sea turtles They feed mainly on plants. The organs of excretion are the kidneys. The need to use water sparingly leads to the fact that the waste products of reptiles contain almost no water.
Circulatory system
The heart of reptiles is three-chambered: it consists of a ventricle and two atria. Unlike amphibians, in the ventricle of reptiles there is incomplete septum, dividing it in half. There are two circles of blood circulation.
In reptiles, internal fertilization is not associated with water. This gave them an advantage in the struggle for existence over amphibians, and they spread widely over land. Reptiles reproduce by laying eggs. After fertilization, the embryo is covered with egg and embryonic membranes. They provide protection and participate in the processes of nutrition and excretion.
Predatory reptiles regulate the number of their victims. Lizards and snakes, feeding on insects and rodents, benefit humans. Snake venom is used in medicine. Beautiful and valuable products are made from crocodile and snake skin.
If you meet a viper in the forest, remember that it never attacks a person first and will try to hide. You should not step on it, try to catch it or kill it. The victim of a bite should be given tea and taken to a doctor as soon as possible. Incisions, application of a tourniquet, and drinking alcohol can only harm him.
