Is the crocodile a reptile or amphibian? Similarities and differences
In the modern world, it is commonly believed that crocodiles- distant relatives of dinosaurs. Indeed, in their appearance, one can imagine the giants of the ancient monsters. Today, crocodiles are well studied and assigned to a separate class. However, people are often confused about which one. Is the crocodile a reptile or amphibian? What is the difference between these two classes? Let's look at them in more detail.
Amphibians, or this class is also calledamphibians, is very different from all other vertebrates. The very first difference is that they have two stages of development. The first - at a young age amphibians are like fish. They also have a tail, gills, and they are born in water. The second stage in development is the emergence of amphibians from the water and the restructuring of the whole organism for life both in water and on land: lungs develop, the tail disappears. The most obvious example in this case is a frog.
In the presence of such differences, why doesquestion: is the crocodile a reptile or amphibian? The fact is that the crocodile lives in water, has light and also to some extent can be considered amphibian. But he does not have the stages of rebirth, as in amphibians. Crocodiles are born already fully formed and not in water, but on land. And only after a while, as it were, they return to the aquatic environment. And now we will consider why the crocodile is a reptile.
The class of Reptiles is not onlycrocodiles, but also snakes, turtles and lizards. Everyone has similarities with amphibians and there are many differences. So, all reptiles are cold-blooded animals. Therefore, their main habitat is the tropics and subtropics. In addition, the body of reptiles is covered with scales that protect the delicate skin. The crocodile has such strong skin that it can not be damaged in any way. Interestingly, unlike other reptiles, crocodiles do not shed, and their skin grows with them.
Another difference from amphibians isstructure of the skeleton. All reptiles have cervical vertebrae, which allow you to turn your head. In addition, reptiles do not have dermal respiration, as in amphibians, but breathe due to the developed respiratory system. Even in all reptiles, fertilization takes place inside the body, in contrast to amphibians, and the cubs are born fully formed.
Features of the structure of the crocodile
The crocodile differs from its structure not only fromamphibians, but also from the majority of reptiles. The exterior of the crocodile is awesome, and it really looks like an ancient dinosaur. The length of the reptile - from 2 to 6 meters, it inspires fear. The head is arranged in a special way: it is flat, with a long snout, on which there are nostrils. The eyes are located at the top, and when in the water the crocodile can only expose the eyes and nostrils. In this case, it is very difficult to notice it.
In addition, the heart of the crocodile differs froma similar organ in other reptiles in that it has four chambers, not three. This indicates a more perfect circulatory system and brings the crocodile closer to mammals. But in the circulatory system of the crocodile there is a controlled system for mixing arterial blood with the venous blood. It helps in the process of digestion and prevents infection from being in dirty water.
Another indication, by which one can determine,crocodile - reptile or amphibian, is a method of reproduction. A female crocodile lays eggs, but not in water, like amphibians, but on land. She digs them in the sand near the water. The female protects the nest from uninvited guests, being near the masonry. It is interesting that all the eggs hatch at the same time, and the sex of the kids depends on the temperature of the environment. If the temperature exceeds 34 degrees, the females will hatch, and if it is in the range from 30 to 34, then the males.
Before the very appearance of the smallcrocodiles give the mother a signal, and she carefully digs out the clutch, helping them to get out of the nest. This is not done by all other reptiles. The crocodile also carries its babies in the mouth to the water. You can imagine how these huge jaws gently take the crocodile and move them to the pond. Also, sometimes crocodile helps to move to water and newborn turtles.
Types of crocodiles
In nature, there are 21 species of crocodiles. All of them differ in size, place of habitation and structure of the head. Most often confused crocodile and alligator. An interesting point: they differ in the structure of the muzzle. At a crocodile it sharp, and at an alligator - more blunt. Teeth with a closed mouth are visible only in crocodiles. The crocodile's heart pumps blood faster, and due to this the salt exchange is faster than that of alligators. This feature allows crocodiles to live not only in fresh water, but also in the sea.
There are small crocodiles, for example caimans,which can be kept at home. This often happens, because the caiman is able to adapt well to any conditions. The only thing that he lives only in clean water, and it's easy to create in a house or a zoo.