Crocodiles are sometimes rightly called dinosaurs that survived on Earth as a miracle. They are one of the most dangerous predators. They belong to chordates. Reptile class. Semi-aquatic wild animal. It looks slow, like a turtle. But, attacking the victim, it can surprise with unprecedented agility and dexterity. Crocodiles are reptiles. This family includes alligators, caimans and Nile crocodiles.
In this article you will find a description of the skeleton of a crocodile, general information about these animals, interesting facts from their lives and more.
Meet the crocodile
Crocodiles appeared more than 250 million years ago. Over this long period, scientists do not note significant changes in the appearance of animals of this species. The only thing is that the ancestors of the now existing crocodiles were much larger. They were thirteen or fourteen in length.meters. In connection with such a constancy of similarity with the ancestors of crocodiles, they are considered unique creatures that allow us to optimize our understanding of the animal world that exists many millennia ago.
These are the largest reptiles on Earth. Live in the tropics and subtropics:
- America;
- Africa (the mainland on which the largest representative of the species lives - the Nile crocodile);
- Asian;
- Oceania (the habitat of the most mysterious, combed crocodiles).
The skeleton of a crocodile consists of bone elements and is somewhat similar to the skeleton of a lizard. Its entire body is covered with horny scales, under which there is a shell in the back and tail surface. Which, in turn, consists of osteoderms. These are such bone plates. On the head they fuse with the skull. Between themselves, these plates are elastically connected. These two facts explain why the "armored coating" does not interfere with the graceful and dexterous movement of animals and the very rapid change of body position both in water and on land.
Together, bone plates and their connection create a kind of "armor" in which the body of a crocodile is located. Its "drawing", including the color, is different for each species and is a distinctive feature. The functions of such "armor" are obvious. This is an effective protection of the whole body, internal organs, brain from various types of influences in the process of life.
Features of the crocodile skeleton
Crocodiles are vertebrates that prefer to live inwater. The most favorite position of the animal, which gives him maximum comfort, is the body almost completely immersed in water. Only a pair of eyes and nostrils remain on the surface of the water, which make up the sensory apparatus of crocodiles. This position allows you to hide the real size of the animal.
The skeleton of a crocodile has its own characteristics.
- Very large head with a flattened back.
- The skull is made up of more than thirty bones.
- Elongated muzzle with elongated upper and lower jaws ending in raised bulging nostrils.
- The limbs are set aside from the body and have five (front) and four (rear) fingers. Three of them end inside with sharp and powerful claws.
- Long tail.
- The spine is divided into sections - cervical, thoracic, lumbar, caudal and sacral - and has sixty to seventy vertebrae.
The study of the structure of the crocodile by specialists from different countries does not stop. There are more and more new facts. For example, the recent discovery of an additional joint in the jaw apparatus of a reptile provides an explanation for the peculiarities of their closing when catching prey, which is called the "dead grip".
Description
The skeletal structure of a crocodile is very similar to that of a lizard. The skeleton of the animal consists of a skull, five sections of the spine and bones of the limbs. The way the body of the animal is arranged speaks of the historical way of adapting to life in water. Elongated and flattened body. Long, mobile tail. short paws,located on both sides of the body. The membranes that connect the fingers of the limbs of crocodiles to each other.
The skeleton of a crocodile is represented by the following components:
- Skull bones. Lower and upper jaws with teeth.
- Cervical, thoracic, lumbar, sacral, tail.
- Thigh bone.
- Leg bones: shin and fibula.
- Forelimb: ankle and metatarsus (the bone that forms part of the foot between the ankle and toes).
- Phalanx: each of the small bones that form the fingers.
- Shoulder.
- Scapula.
- Forearm bones.
- Rib: Each of the bones that make up the ribcage.
This photo of a crocodile skeleton clearly shows the sacral vertebrae and their articulation with the femur on one side and the sacrum on the other.
The perfection of the musculoskeletal, nervous, circulatory and respiratory systems allows us to consider these animals the most highly organized of all living reptiles.
Jaws and teeth
Description of the bones of the skeleton of a crocodile should begin with a description of the dento-jaw system of the animal. The jaws of a reptile are designed to capture and hold prey. The teeth are conical and serve to penetrate and hold prey rather than cut or chew. The teeth of the upper and lower jaws are in perfect contact when they are closed. This is one of the explanations for the fact that when captured, they firmly hold the victim, creating the notoriousstranglehold.
Teeth are often lost, but beneath every one there is a replacement ready to fill the vacancy. Teeth are replaced approximately every twenty months throughout life. This process slows down a little as the animal grows older and may stop altogether in the oldest and largest individuals. The number of teeth varies from sixty to one hundred and ten in different species.
The muscles that close the jaws are capable of generating tremendous force. They easily crush the tortoise shell. Easily able to crush the skull of a pig. But the muscles that open the jaws have less strength. So, a rubber strip around the mouth of a two-meter crocodile is enough to keep it from opening its mouth. Conversely, two strong people equipped with various levers can hardly open the mouth of a crocodile more than one meter long.
Although crocodile jaws have great strength, they are also able to act delicately and gently. Large adults collect and roll the unpeeled eggs between their jaws, gently squeezing them until the crocodiles hatch. Females of most species carry their newly born babies to the water in their mouths.
Structure of the nasal disc and palatal valve
The animal's head "begins" with the nasal disc at the tip of the upper jaw. It contains two nostrils, each with a protective valve at its opening. They lead to channels that pass through the bone of the mouth and open into the back of the throat. Along these channels are chambers with receptors,distinguishing odors. Crocodiles have a very good sense of smell.
The second way of breathing is through the mouth. At the back of the throat is the palatine valve, which opens or closes reflexively. When the animal is basking on the ground with its mouth open, breathing is carried out mainly through the mouth (the palatal valve is open). When it is in the water, the mouth is usually closed and the crocodile breathes mainly through the nostrils. If the prey is held in the water, the mouth may be open, but the palatal valve is closed.
Sensory pits
A feature of the crocodile skull is that it is represented by the left and right temporal arches and is very reminiscent of the skull of ancient animals - dinosaurs. The eyes, ears and nostrils are close to the top of the head.
Speaking of the external skeleton of a crocodile, it is worth mentioning the scales covering the animal's head. They are very thin compared to the scales on the rest of the body and have prominent sensory pits. The latter contain bundles of nerve endings and are involved in detecting movement or vibration in water.
Exoskeleton
The "external skeleton" of crocodiles consists of a network of interconnected scales or scutes of various shapes and sizes. On the ventral surface, they tend to be square and flat. On the sides and on the neck - round, with a raised center. Along the back and upper surfaces of the tail, the scales are raised very clearly.
Bone formations are part of the crocodile skeleton, which consists of discrete and isolated blocks called "osteoderms". Their relief is most pronounced along the back. Provided with a rich blood supply. Degree, inwhich they are deposited in the ventral part of the body varies between species and within the same species from different subspecies.
Bone scales along the back are "armor". Some species are considered more heavily armored than others. This difference greatly affects the ability to protect delicate internal organs from injury during fights with other crocodiles. Therefore, teeth marks on them are quite common.
The vertical scales along the tail (shields) are hardened. They substantially increase the surface area of the tail and play a role in swimming efficiency. They have a good blood supply. They are places of heat exchange between the animal and the environment.
Spine
The axial skeleton of a crocodile is represented by a very mobile and strong spine. It is he who allows the reptiles to cope with fairly high loads when moving and fighting for survival. With the exception of some marine genera, all crocodiles have twenty-four presacral vertebrae, two sacral vertebrae, and thirty to forty caudal vertebrae. In modern reptiles, the first nine vertebrae are cervical. The ribs are simple rods with slightly flared heads that connect them to the spine.
Today there are many manuals and textbooks on zoology with the name of the bones of the crocodile skeleton, which are quite well studied.
Limbs
All modern crocodiles are quadrupedal and on land have a wide spreading stance. They have three ways of groundlocomotion: crawl on the stomach, walk with the body raised above the ground and jump. An adult crocodile can reach a fairly high speed both when crawling and when jumping. In the hind limbs of reptiles, a sufficiently developed calcaneal tubercle is of particular importance. It becomes a powerful lever tool for foot flexion. It is this fact that allows crocodiles to walk on the surface without lowering their bodies to the ground. And this way of movement characterizes mammals.
Tail
The skeleton of a crocodile includes a very powerful tail section, depending on the species, consisting of thirty to forty vertebrae. While swimming, the tail is the main tool used, as the limbs are rather passive in this process. Despite their apparent bulkiness on land, crocodiles are very skilled swimmers and can move at great speeds when necessary. The strength and ability of the tail of the animal is such that crocodiles during the hunt are able to jump out of the water and stay above its surface in order to catch prey. From the outside, it seems that the reptile, while jumping after the victim, seems to be standing on the water.
An interesting fact: it takes a crocodile just two hundred milliseconds to jump out of the water and grab its prey. For comparison: a person blinks twice as slowly.
The tail, one might say, "ends" the skeletoncrocodile - photo of this section of the spine below.
It is an additional weapon for hunting both on land and in water. The ability of crocodiles to remain motionless for a long time and the fact that their tail can be confused with a snag (or other object) dulls the vigilance of potential prey. And the reptile can unexpectedly use it to stun the victim.
Organ of hearing
Crocodiles are believed to have the most developed hearing organ of all reptiles. In terms of importance for life and safety, it is in second place after vision.
The skull of a crocodile contains a fairly well-formed anatomically slit-like external auditory meatus. Its end is closed with a valve. This happens when the animal is completely submerged in water.
The right middle ear is connected to the left and to the pharynx through a complex system of adnexal cavities. Their opening occurs in the tympanic cavity. The inner ear has a cochlea. The same as in birds, but completely absent in other reptiles. Based on this fact, it can be argued that the hearing of crocodiles is similar to the hearing of birds.
Crocodile skin
Crocodiles prefer to spend most of their lives in the water. Perhaps this saved them from death during the global cooling on Earth many hundreds of thousands of years ago. But it does not save us from extinction in our time. The pursuit of their expensive leather, which is used in the manufacture of luxury products: handbags, shoes, belts, and so on. - one of the reasons why there is a decrease in the number of animals byEarth.
The entire skin of crocodiles is divided into sensitive and insensitive areas. The most sensitive is under the abdomen or on the sides of the animal. For the sake of this small piece of raw material measuring forty-five to forty-seven centimeters, they destroy a whole crocodile.
From the fifties of the last century, they began to create farms where animals are specially raised in order to obtain raw materials for the haberdashery industry. But so far, this does not save the crocodiles from destruction for profit.
Ecological changes are also not the last factor influencing the decline in the number of populations of various crocodile species.
Green Dragon
The fact that the appearance of a crocodile resembles the appearance of a mythical dragon made them the heroes of fairy tales and legends. But, unfortunately, more often negative heroes. In some cultures, crocodiles are considered sacred animals, symbols of power and strength.
Not all kinds of animals are dangerous. The most terrible are the Nile and combed ones. Unlike gharials, which don't attack humans at all.
Conclusion
Terrible, toothy, weeping predators. When bitten, a crocodile's jaws can exert up to 16,400 Newtons of pressure. By comparison, the human jaw has a relatively small force of 500 Newtons. This is just one of the many interesting facts about this animal, which, along with a description of the skeleton of a crocodile, with signatures of the names of bones and departments, is available in this article.
