Reptiles are an example. Amphibians and reptiles

Each of us, even if only in pictures, saw frogs and lizards, crocodiles and toads - these animals belong to the classes Amphibians and Reptiles. The example given by us is far from being the only one. There are a lot of such creatures. But how to distinguish who is who? Amphibia and reptiles differ, and how significant are these differences?

The crocodile and the toad can perfectly get along in one pond. Therefore, it is likely that it may seem as if they are relatives and have common ancestors. But this is a huge mistake. These animals belong to different systematic classes. There are many fundamental differences between them. And they are not only in appearance and size. The crocodile and the lizard are reptiles, and the frog and the toad are amphibians.

But, of course, amphibians and reptiles also have some similarities. They prefer areas with a warm climate. True, amphibians choose wet places, preferably near water bodies. But this is dictated by the fact that they multiply only in water. Reptiles are not connected with water bodies. They, on the contrary, prefer more dry and hot regions.

Let's look at the structure and physiological characteristics of reptiles and amphibians, and compare how they differ from each other.

Class Reptiles (reptiles)

Class Reptiles, or Reptiles are terrestrial animals. They got their name because of the way they moved. Reptiles do not walk on the ground, they creep. It was the reptiles that for the first time completely switched from water to land life. The ancestors of these animals settled widely on the ground. An important feature of reptiles is internal fertilization and the ability to lay eggs that are rich in nutrients. They are protected by a dense shell, which includes calcium. It was the ability to make egg-laying that promoted the development of reptiles outside the reservoir on land.

The structure of reptiles

The body of reptiles has strong formations - scales. They tightly cover the skin of reptiles. This protects them from moisture loss. The skin of reptiles is always dry. Evaporation through it does not occur. Therefore, snakes and lizards are able to live in deserts without experiencing any discomfort.

Breathing reptiles with well-developed lungs. It is also important that intensive breathing in reptiles became possible due to the appearance of a fundamentally new department of the skeleton. The thorax first appears precisely in reptiles. It is formed by the ribs that extend from the vertebrae. From the ventral side they are already connected to the sternum. Due to the special musculature, the ribs are mobile. This contributes to the expansion of the chest at the time of inspiration.

The Reptilian class has undergone changes from the circulatory system. This is due to the complication of the structure of the lungs. The overwhelming majority of reptiles have a three-chambered heart, they, like amphibians, have two circles of circulation. However, there are some differences. For example, in the ventricle there is a septum. With a contraction of the heart, it practically divides it into two halves (right - venous, left - arterial). The location of the main blood vessels clearly delineates the arterial and venous streams. As a result, the body of reptiles is supplied with blood enriched with oxygen, much better. At the same time they have more established processes of intercellular metabolism and the withdrawal of metabolic products and carbon dioxide from the body. There is an exception in the class of Reptiles, an example is a crocodile. His heart is four-chambered.

The main large arteries of small and large circles of circulation are fundamentally the same for all groups of terrestrial vertebrates. Of course, without small differences, it did not. Reptiles in a small circle of blood circulation disappeared skin veins and arteries. Only the pulmonary vessels remained.

Currently, about 8 thousand species of reptiles are known. They live on all continents, apart from, of course, Antarctica. Separate four detachments of reptiles: crocodiles, scaly, turtles and pioneers.

Reproduction of reptiles

Unlike fish and amphibians, reproduction in reptiles is internal. They are dioecious. The male has a special organ, by means of which he introduces spermatozoa into the cloaca. They penetrate into the ovule, after which fertilization takes place. Eggs develop in the body of a female. Then she lays them in a pre-prepared place, as a rule, it's a dug hole. Outside, reptile eggs are covered with a dense calcium shell. They contain an embryo and a supply of nutrients. Out of an egg, not a larva appears, as in fish or amphibians, but as individuals capable of independent life. Thus, the reproduction of reptiles basically comes to a new level. The embryo undergoes all stages of development in the egg. After hatching, it does not depend on the water body and may well survive on its own. As a rule, adults do not care about their offspring.

Class Amphibians

Amphibians are frogs, toads and newts. They, with rare exceptions, always live near the pond. But there are species that live in the desert, for example, a toad-aquifer. During the rain, she picks up the liquid in the subcutaneous sacs. Her body swells. Then it buries into the sand and, releasing a large amount of mucus, is experiencing a prolonged drought. Currently, about 3400 species of amphibians are known. They are divided into two orders - tailed and tailless. The first include salamanders and newts, to the second - frogs and toads.

Amphibians strongly differ from the class Reptiles, for example - the structure of the body and organ systems, as well as the way of reproduction. Like their distant ancestors fish, they spawn in the water. For this, amphibians often look for puddles separated from the main body of water. Here occurs both fertilization and the development of larvae. This means that during the breeding season amphibians have to return to the water. This greatly hampers their resettlement and limits movement. Only a few species were able to adapt to life in the distance of water bodies. They give birth to the formed offspring. That's why these animals are called semi-aquatic.

Amphibians - the first of chordates, in which limbs developed. Thanks to this in the distant past, they were able to reach the dry land. This, naturally, caused in these animals a number of changes not only anatomical, but also physiological. In comparison with the species remaining in the aquatic environment, the amphibians have a broader chest. This contributed to the development and complication of the lungs. The amphibians improved their hearing and vision.

Habitat amphibians

Like reptiles, amphibians prefer to live in warm regions. Typically, frogs are found in wet places near water bodies. But you can see them both in meadows and in forests, especially after heavy rain. Some species feel great even in deserts. For example, the Australian toad. She very well adapted to survive a prolonged drought. Under such conditions, other species of toads would inevitably quickly perish. But she learned to accumulate the vital moisture in the subcutaneous pockets during the rainy season. In addition, during this period, it multiplies, laying eggs in puddles. Tadpoles for a complete transformation is enough for one month. The Australian toad in extreme for its kind of conditions not only found a way to reproduce the offspring, but also successfully find for myself the writing.

Differences of reptiles from amphibians

Although at first glance it seems that amphibians do not differ much from reptiles, this is far from being the case. In fact, there are not many similarities. Amphibians have less perfect and developed organs than the class Reptiles, for example - amphibian larvae have gills, while the offspring of reptiles are already born with formed lungs. In fairness, it should be noted that both newts, and frogs, and turtles, and even snakes, can quite coexist on the territory of one pond. Therefore, some do not see significant differences in these units, often confusing who is who. But the fundamental differences do not allow to combine these species into one class. Amphibians always depend on their place of residence, that is, a reservoir, in most cases they can not leave it. With reptiles, everything is different. In case of a drought they can quite easily make a small trip and find a more favorable place.

This is possible in large part due to the fact that the skin of reptiles is covered with horny scales that do not allow moisture to evaporate. The skin of reptiles is devoid of glands secreting mucus, so it is always dry. Their body is protected from drying out, which gives them clear advantages in a dry climate. Reptiles are characterized by molting. For example, the body of a snake grows all his life. Her skin is "wear out". They restrain growth, so once a year it "dumps" them. Amphibians have naked skin. It is rich in glands secreting mucus. But with a strong heat amphibian can get a heat stroke.

Ancestors of reptiles and amphibians

The ancestors of amphibians were brush-fishes. Of their paired fins, later formed five-fingered limbs. The external structure of reptiles indicates that their distant ancestors were amphibians. This is evidenced by both anatomical and physiological similarity. Among vertebrate detachments, they first left the aquatic environment and went ashore. For many thousands of years they dominated other species. The end of this was the accession of mammals. Why this happened is not known for certain. There are many assumptions, most of which are supported by undeniable evidence. This is a global catastrophe, caused by the fall of the meteorite, and the appearance of flowering plants, and climate change. Subsequently, many reptiles returned to the aquatic environment. But their internal organs remained perfectly suitable for life on land. Currently, the representative of such species is the sea turtle.

Differences in the structure of organs

Amphibians and reptiles breathe atmospheric air through the lungs. But amphibian larvae retain gills. Reptiles do not have them. In addition, reptiles have a more complex nervous system. They have rudiments of the cerebral cortex, more developed cerebellum and sense organs. Crocodiles, lizards and chameleons are better adapted to life on land. They have more perfect hearing, sight, and enough developed organs of taste, smell, and touch. There are practically no taste receptors for amphibians. Although they have a well-developed, keen sense of smell.

Reptiles have complicated blood and excretory systems. Their blood in large vessels is better divided into arterial and venous. In addition, the reptiles disappeared skin vessels, which are very developed in amphibians. This is due to the fact that about half the oxygen of the frog and the newts are obtained with the help of skin respiration. Being under water, they do not use lungs. Reptiles in the same way can not absorb oxygen. Therefore, skin arteries and veins are not needed. They breathe extremely well developed lungs.

Amphibians and reptiles have a different number of spine sections. Reptiles have five, and amphibians have four. In tailless species, ribs are absent.

Difference in the ways of reproduction

Fish, amphibians, reptiles significantly differ in the mode of reproduction. In reptiles, insemination is internal. Eggs are formed inside the female. Then, as a rule, she lays them in a dug hole and drops them on top. Similarly, both crocodiles and turtles act. Cubs hatch fully developed, from adults they differ only in size. There are also viviparous reptiles. They "give birth" to the light of a formed cub in a leathery shell. This way of reproduction is inherent in some types of snakes. The born calf breaks the shell and creeps away. He leads an independent life. It was the ability to make egg laying in a hard shell that gave evolutionary advantage to reptiles in front of amphibians. This made possible their resettlement in various parts of the earth. They exist in forests, deserts, mountains and on plains. Features of the structure of reptiles allow them to live in water.

In amphibians, reproduction takes place in a body of water. Females spawn in water. There, males start up spermatozoa that fertilize the eggs. First hatched larvae. Only in two or three months they will finally turn into cubs.

The life of reptiles and amphibians

Many amphibians are only born in the water, and they spend their entire adult life on land. But there are species of amphibians, for example, newts, which do not leave the aquatic environment. Under adverse conditions, such land species as frogs and toads can return to the pond again. Amphibians feed on plant foods and invertebrates. They do not live long. Some species of toads can live up to 8 years, and newts - only 3 years.

The peculiarities of reptiles are that they do not depend on water. They are able to multiply and in its absence. Reptiles eat a variety of food. The diet of small lizards includes insects. Snakes hunt for rodents. They can eat and eggs of birds. Crocodiles and lizards prefer herbivorous mammals - roe deer, antelope and even large buffalo. Turtles consume vegetable food. Reptiles are real long-livers. Land tortoises, whose age is more than 200 years, were discovered. Crocodiles can live 80 years, and snakes and lizards - up to 50 years.

conclusions

Reptiles differ from amphibians in the following parameters:

1. Habitats. Amphibians prefer wet and damp places near water bodies. Reptiles are not associated with water.

2. The skin of reptiles is devoid of glands. It is dry and covered with scales. In amphibians, on the contrary, it is strewn with glands that secrete a large amount of mucus.

3. Reptiles are characterized by molting.

4. Ancestors of reptiles - amphibians.

5. Reptiles have more developed and improved nervous and circulatory systems.

6. In crocodiles, lizards, snakes and other species, fertilization is internal.

7. Amphibians have four spine sections, and reptiles have five. In this there are similarities between mammals and reptiles.

Interesting Facts

The largest reptiles that ever existed on earth are dinosaurs. They disappeared about 65 million years ago. They inhabited the sea and the land. Some species were able to fly. At present, the most ancient reptiles are turtles. They are more than 300 million years old. They existed in the era of dinosaurs. A little later there were crocodiles and the first lizard (photos can be seen in this article). Snakes are "only" 20 million years old. This is a relatively young species. Although it is their origin that is currently one of the great mysteries of biology.