Class Reptiles: General

Very interesting and very unusual creaturesare reptiles. The general characteristics of these creatures are very detailed. Which is not surprising, because this class of chordate terrestrial animals includes snakes, lizards, amphibians, bee-eaters, crocodiles and turtles. All of them have many distinctive features. Of course, everything can not be briefly told, but the most interesting is complete.

A bit of history

Where do the reptiles come from? A general characteristic always begins with information about it. It is logical, because everyone will not be prevented from knowing that terrestrial animals belonging to this class are distant descendants of dinosaurs that dominated the Mesozoic era for more than 160 million years. As you know, they died out about 66 million years ago. Modern reptiles can only be compared with the scattered remnants of that beautiful, mysterious ancient world.

It is also important to know that the ancient reptilesare the ancestors of birds. They gave birth to this group of animals, which is now actively thriving. Scientists have long found out that the adaptations that conditioned the evolution of birds were observed in their ancestors - representatives of special forms of reptiles. They were characterized by warm-bloodedness, developed brain and insulating covering of the body (feathers).

Cover

Now - a little more details aboutThe anatomical specificity inherent in creatures such as reptiles. The general characteristic states that they have features of both amphibians and higher vertebrates. What about the outer cover? He, because of the thickening and subsequent keratinization, forms shields and scales. Such a cover protects the tissues and organs of the animal from the action of external stimuli and from the loss of moisture.

And legless lizards and snakes scales help to move. Due to the presence of plates, animals repel from uneven ground and move in one direction or another.

The covers of reptiles are different. In some creatures, the scales fit tightly to each other. In others, they go like a "lap". Some even transform into crests or thorns, due to which the creatures are protected from predators.

But one of the most interesting covers can beto observe moloch (Latin Moloch horridus) in a lizard. It is also called "prickly devil". Looking at the photo provided above, you can understand why. This small, lizard-dwelling Australian has a wide and flattened body, covered with innumerable short, curved, horny thorns of varying sizes. Over the eyes and on the cushion-like growth on the neck they form something resembling horns. This golden brown lizard is able to change its color depending on the lighting, temperature and its physiological state.

But it's worth returning to the subject of the cover. Does it prevent the growth of reptiles? No, because they periodically discard the old skin. And in the process of molting their growth takes place. And the new cover is elastic and soft. Its keratinization takes time, and during this period these creatures hide, because they are vulnerable without protection.

Structure of the skeleton

It is also important to mention it, if we talk about how,what anatomical features are reptiles. The general characteristic is very interesting, because the total number of vertebrae can reach several hundred! In the adult giant anacondas (Latin Eunectes murinus), for example, there are about 435 of them! It's impressive. But if you exclude snakes, the total number of vertebrae of other reptiles varies from 50 to 80.

But the structure of the axial skeleton is identical for all. And by the way, the division into departments is much more pronounced than in the case of amphibians. There are five distinct vertebral divisions: cervical, trunk, lumbar, sacral and caudal. In the last of these concentrated maximum number of notorious vertebrae. They have a very interesting structure: the closer to the tail, the smaller their size. The last vertebrae and at all in structure are similar to tiny bones in the form of sticks.

However, in some groups of reptiles the skeleton hasother structure. For snakes, for example, only the trunk and tail sections are clearly visible. No sternum. And the vertebrae of the trunk portion of the turtles and completely fuse with the shield of the shell, because of what they lose their mobility.

Skull

Also, the general characteristics of reptiles can bemuch to tell about the structure of the skull of these creatures. Especially about the snake. Its structure evolved depending on the methods of obtaining food and the nature of nutrition.

In amphibians, for example, a short and wide skull has elongated jaws, which form a very long snout. The structure of the mouth allows these creatures to capture small prey when attacking it.

But the reptiles catch the booty directlyis associated with the victim's persecution. And elongated snout here has significant advantages. In addition, it is this kind of jaw that allows you to tear off a piece from a large prey. In crocodiles and turtles, incidentally, the palatine processes form a secondary skeleton palate, which divides their oral cavity into the lower and upper divisions. Therefore, they can breathe by exposing the end of the head with the nostrils from the water, because the choana (inner nasal apertures) are shifted back, closer to the larynx.

Muscular system

Its description also includes a generalcharacteristic of reptiles. The muscular system of these creatures is differentiated, represented by segmental musculature. A distinctive feature of these creatures is the intercostal muscles, performing the most important functions in the implementation of respiration.

Of particular interest is the subcutaneous musculature. In some representatives, it is so strongly developed that it allows the beings to change the position of the scales. This, by the way, has already been mentioned in the cover section.

The role of energy "make-up" for the muscles of thesecreatures plays an anaerobic decomposition of glucose. It is interesting that most of the muscles (50-75%) can work even without oxygen saturation. Due to this reptiles can overcome small distances as quickly as warm-blooded animals. Muscles contract quickly. But if the creature "overdo it," active accumulation in the muscles of lactic acid, the excess of which leads to fatigue, will begin. Therefore representatives of this class, having made several dashes, hide for rest. Within a few hours lactic acid breaks down, and the strength of the animal is restored.

Musculature of snakes

We must talk about it separately. The general characteristic of a detachment of reptiles can not convey all its specifics. The fact is that the muscles of the snake are used to move the food swallowed by it inside, and not just for movement.

It is also important to know what the four mainthe type of their movement. The most famous is called serpentine, lateral or sliding. Characterized by a wavy form of movement. It is this method that allows snakes to swim and reach high speeds. The record holder, by the way, is the poisonous black mamba (Latin Dendroaspis polylepis) that lives in Africa. Its average speed is 11 km / h.

There is also a straightforward way to travel(the technique of "caterpillar"). Snakes move forward on the skin of the abdomen, and then pull the entire back of the body. In the third method, called parallel, the animal seems to throw itself aside (lateral cycle of motion). To see this is a rarity. This method is peculiar to snakes living on loose sand, in deserts.

The fourth method is no less rare. It is called "concertina. Or, in other words, the technique of "accordion". Applies when moving a snake through a tree. It looks unusual, because the body seems to be going to form horizontal loops, after which the head rushes forward, due to which the "accordion" straightens.

All this is very unusual, but it explainsexternal structure and skeleton of reptiles. The general characteristic, of course, helps to understand approximately what it is "from within", but after observing the movements described above, you can visualize everything.

Nervous system

It is also important to mention it,class Reptiles. The general characteristic of the nervous system is detailed. But before discussing it, it is worth noting that the central nervous system of these creatures is represented by the spinal cord and the head, consisting of five departments.

The first is the front one. It is from his hemispheres olfactory lobes depart.

The second is in between. In its lower part is the pituitary gland, and in the upper part - the epiphysis. It is next to him, by the way, a unpaired photosensitive organ, called the parietal eye, develops in hatteria (the only modern representative of the beak-headed group) and lizards. And the crocodiles, by the way, do not have a pituitary gland or an epiphysis.

The third department is called the middle department. It is represented by visual stakes. In this regard, too, distinguished class Reptiles. The general characteristic allows us to understand that their middle section and the visual cortex are much more developed than in amphibians. The last component of the brain is the cerebellum. And another oblong department.

However, this is not all that is worth knowing about the classReptiles. The general characteristic, briefly, makes it clear that the representatives of this category of animals are distinguished by a developed physiological and anatomical structure. But it is also important to know that in their spinal cord, separation into gray and white matter is much more clearly marked, in contrast to the same amphibians. And they also have a pronounced parasympathetic and sympathetic autonomic nervous system. It is represented by a chain of paired nerve congestions (ganglion).

Sight and Smell

This, perhaps, is the most interesting topic. And the general characteristics of reptiles (or reptiles) will be incomplete without mentioning it.

So, these creatures have six senses. The first is sight. It is interesting that many lizards perfectly distinguish colors. Shades - the most important means of their communication. Poisonous insects, they recognize precisely by color. And giant turtles are also capable of perceiving colors. On red, many of them respond well. There is even a hypothesis that turtles know how to perceive infrared light.

Snakes and crocodiles of flowers do not distinguish. But in reptiles the eye has the same structure as in humans. And some of their representatives have eyelids. Moreover, the lower ones are more mobile than the upper ones. Pupils, by the way, in reptiles are different. In representatives who lead a nocturnal or twilight way of life, it is vertical. And geckos on the narrowed pupils and at all you can see the point holes, which focus on the retina independent image. This feature ensures maximum sharpness of the reality displayed for the lizard.

What about the sense of smell. A general characteristic of reptiles can also tell about its specifics. Briefly, the main role in the olfaction of these creatures is played by chemoreceptors. Due to these animals, they very well perceive the smell. They are able to find food buried at a depth of up to 8 centimeters. Vipers, stags and lizards due to the sense of smell can determine the type of approaching animal long before it appears in sight. And crocodiles, lizards and turtles, and do have special glands, the secret of which is intended to "designate" the occupied territory. An odorous substance, these creatures mark their patches.

Lifestyle

About it also can tell the general characteristics of reptiles. Grade 7 - approximately at this stage in high school this subject is being studied.

So, the vast majority of animals,belonging to this class, are carnivorous. Reptiles mainly feed on carrion and insects. But the present predation is peculiar only to some lizards, crocodiles and snakes. Iguanas and agamas can eat anything - starting with vegetables and fruits, ending with animal meat. However, there are also exclusively herbivorous creatures. These include land tortoises.

Interesting reproduction occurs. It is important to mention it, telling about the class Reptiles (or Reptiles). The general description briefly explains how everything happens.

So, insemination is internal. The embryo develops in an egg that is covered with either calcareous or leathery membranes. Eggs and eggs are also found. Very rarely cubs are born, as in viviparous animals. It is worth noting that the care of the offspring of these creatures is inherent. Female crocodiles, for example, carefully carry their babies from the masonry to the reservoirs in the mouth.

And it's interesting to know that the overwhelmingmost reptiles do not have a voice device. Nothing, except a whistle or hiss, they can not publish. So no marriage cries can be heard - these beings are guided by the smell. Only Euphéfar lizards are capable of squeaking.

Interesting representatives

Well, the general characteristics and features of the external structure of reptiles were considered above. Finally, you can tell about some rare representatives.

The smallest creation of this classis a squeaky gokonchik, living in deserts and semi-deserts. You can find it in the areas where the Volga flows. This amazing creature, covered with granular scales. The length of his body reaches only 41 mm! He has about the same tail, which is easily discarded.

Deserves attention and Gyurza, which is the largest representative of the genus of giant vipers. It is a toxic creature weighing 3 kilograms, the length of which reaches 2 meters.

But with the royal cobra, of course, gyurza can not be compared. After all, this is the largest venomous snake. Some individuals reach a length of 5.6 m. Grow, by the way, throughout life. And they live up to 30 years.

A snake like Taipan is very attractiveMcCoy. Only a beautiful creature with golden-black scales is very dangerous. This is the world's most poisonous snake. The venom of one individual (44 mg) is enough to kill a quarter of a million mice or 100 people.

Of course, this is by no means all amazingBeings that abound in the class Reptiles (or Reptiles). A general characteristic allows us to understand how great their diversity is. But still worth noting the attention of the Far Eastern skink. This is a lizard that can be found in Japan or the Kuril Islands. It, like all the previously listed species, is listed in the Red Book of Russia. And its highlight is an amazing color that can be appreciated by looking at the photo provided above.

Well, on this topic you can still talk for a long time. After all, the world knows 9,400 species of reptiles, and each of them is unique in its own way. But they can be read individually. All that was said above, it may well awaken to this interest.