Crocodiles are sometimes rightly called the miracle surviving dinosaurs on Earth. They are one of the most dangerous predators. Relate to chordates. Reptile class. Semi-aquatic wild animal. It looks slow as a turtle. But, attacking the victim, it can surprise with unprecedented agility and dexterity. Crocodiles are reptiles. The composition of 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 life and not only.
Meet the crocodile
Crocodiles appeared more than 250 million years ago. For this long period of significant changes in the appearance of animals of this species, scientists do not note. The only thing is that the ancestors of the existing crocodiles were much larger. In length they reached thirteen to fourteen meters. In connection with this constancy, similarities with the ancestors of crocodiles are considered unique creatures that allow us to optimize our ideas about the animal world that existed many millennia ago.
These are the largest reptiles on Earth. They live in the tropics and subtropics:
- America
- Africa (the mainland, on which the largest representative of the species lives - the Nile crocodile);
- Of Asia;
- 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. His whole body is covered with horny scales, under which there is a carapace in the area of the back and surface of the tail. Which, in turn, consists of osteoderms. These are such bone plates. On the head they grow together with a skull. Between each other, these plates are elastically connected. These two facts explain why the “armored coating” does not interfere with the graceful and adroit movement of animals and the very rapid change in body position both in water and on land.
Together, the bone plates and their connection create a kind of “armor” in which the body of the crocodile is located. Its “pattern”, including color, has its own distinctive feature for each species. 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 skeleton of a crocodile
Crocodiles are vertebrates that prefer to live in water for the most part. The animal’s most favorite position, giving it maximum comfort, is the body that is almost completely immersed in water. Only a pair of eyes and nostrils remain on the surface of the water, which make up the crocodile sensory apparatus. 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 flattening in the dorsal region.
- The skull consists of more than thirty bones.
- An elongated muzzle with elongated upper and lower jaws ends with raised convex nostrils.
- The limbs are moved away from the body and have five (front) and four (back) fingers. Three of them from the inside end with sharp and powerful claws.
- Long tail.
- The spine is divided into departments - cervical, thoracic, lumbar, caudal and sacral - and has from 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 the reptile gives an explanation of the peculiarities of their closure when catching prey, which are called "death grip".
Description
The structure of the skeleton of a crocodile is very similar to the structure of the skeleton of a lizard. The skeleton of the animal consists of a skull, five parts of the spine and bones of the limbs. The way the body of the animal is structured speaks of a historical way of adapting to life in water. Elongated and oblate body. A long, movable tail. Short legs 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 jaw with teeth.
- Cervical, thoracic, lumbar, sacral, caudal.
- Femur.
- Leg bones: lower leg and brooch.
- Forelimb: ankle and metatarsus (bone forming the part of the foot between the ankle and toes).
- Phalanx: each of the small bones that form the fingers.
- Shoulder.
- Shovel.
- Bones of the forearm.
- Rib: each of the bones forming the rib cage.
In this photo of the skeleton of a crocodile, the sacral vertebrae and their articulation with the femurs on one side and sacral on the other are clearly visible.
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. Reptile jaws are designed to capture and hold prey. The teeth have a conical shape and serve to penetrate into the body of the prey and hold it, and not cut or chew. The teeth of the upper and lower jaws are perfectly in contact when they are closed. This is one of the explanations for the fact that during the capture they firmly hold the victim, creating the notorious "death grip".
Teeth are often lost, but under each is a replacement, ready to fill a vacancy. A change of teeth occurs approximately every twenty months throughout life. This process slows down a bit as the animal grows older and may generally stop 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 jaw are capable of generating tremendous strength. They easily crush the tortoise shell. Easily able to crush the skull of a pig. But the muscles that open the jaw have less power. So, a rubber strip around the mouth of a two-meter crocodile is enough to prevent it from opening its mouth. Conversely, two strong people, equipped with different levers, can hardly open the mouth of a crocodile more than one meter long.
Although crocodile jaws have tremendous power, they are also able to delicately and gently act. Large adults collect and twist unpeeled eggs between the jaws, gently squeezing them until the crocodiles hatch. Females of most species carry newly born cubs to the water in their mouth.
The structure of the nasal disc and palatine valve
The head of the animal "begins" with the nasal disc at the tip of the upper jaw. It contains two nostrils, each with a safety valve in its opening. They lead into canals that pass through the jaw bone and open into the back of the throat. Along these channels are located chambers with receptors that distinguish 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 a palatine valve that opens or closes reflexively. When the animal warms itself on the ground with its mouth open, breathing is done mainly through the mouth (palatine valve open). When it is in water, the mouth is usually closed, and the crocodile breathes mainly through the nostrils. If production is held in water, the mouth may be open, but the palatine 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 similar to the skull of ancient animals - dinosaurs. The eyes, ears and nostrils are located close to the top of the head.
Speaking about the outer skeleton of a crocodile, it is worth mentioning the scales covering the head of the animal. They are very thin, compared with the scales of the rest of the body, and have pronounced sensory fossae. The latter contain bundles of nerve endings and are involved in the detection of movement or vibration in water.
Exoskeleton
The "external skeleton" of crocodiles consists of a network of interconnected scales or flaps of various shapes and sizes. On the abdominal surface, they tend to be square and flat. On the sides and on the neck - round, with a raised center. Along the rear and upper surfaces of the tail tail, the scales are raised very clearly.
Bone formations are part of the skeleton of a crocodile, which consists of discrete and isolated blocks called “osteoderms”. Their relief along the back is most pronounced. Provided with rich blood supply. The degree to which they are deposited in the abdominal 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 significantly affects the ability to protect the delicate internal organs from injuries during fights with other crocodiles. Therefore, teeth marks on them are a fairly common phenomenon.
The vertical scales along the tail (shields) are hardened. They significantly increase the surface area of the tail and play a role in swimming efficiency. They have good blood supply. 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 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 pre-sacral vertebrae, two sacral, and thirty to forty caudal. In modern reptiles, the first nine vertebrae are cervical. The ribs are simple rods with slightly expanded heads, by which they are connected with the spine.
Today there are many manuals and textbooks on zoology with the name of the bones of the skeleton of a crocodile, which are pretty well studied.
Limbs
All modern crocodiles are four-legged and on land have a wide spreading stance. They have three methods of ground movement: crawling on their stomachs, walking with their bodies raised above the ground, and jumping. An adult crocodile can reach a sufficiently 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 flexing the foot. It is this fact that allows crocodiles to walk on the surface without dropping the body to the ground. And this method of movement characterizes precisely mammals.
Tail
The crocodile skeleton includes a very powerful tail section, depending on the species, consisting of thirty to forty vertebrae. During swimming, the tail is the main tool used, since the limbs in this process are rather passive. Despite the apparent bulkiness on land, crocodiles are very skilled swimmers and can move at high speed when necessary. The strength and ability of the tail of the animal is such that the crocodiles during the hunt are able to jump out of the water and stay above its surface to catch prey. From the side it seems that the reptile during the jump for the victim as if standing on the water.
An interesting fact: to jump out of the water and grab the prey, the crocodile needs only two hundred milliseconds. For comparison: a person blinks twice as slowly.
The tail, we can say, is "ending" in the skeleton of a crocodile - a photo of this section of the spine is below.
It is an additional weapon when 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 snags (or other objects) dulls the vigilance of potential prey. And the reptile unexpectedly with his help can stun the victim.
Organ of hearing
Crocodiles are believed to have the most developed hearing organ of all reptiles. In importance for life and safety, it is in second place after vision.
The crocodile skull contains a fairly well-formed anatomically slit-like external auditory meatus. Its end is closed by a valve. This happens when the animal is completely immersed in water.
The right middle ear is connected with the left and c pharynx with the help of a complex system of accessory cavities. Their opening occurs in the tympanic cavity. The inner ear has a snail. The same as y birds, but completely absent y remaining reptiles. Based on this fact, it can be argued that the hearing of crocodiles is similar to the hearing of birds.
Crocodile leather
Crocodiles prefer to dwell in water for most of their life. Perhaps this saved them from death during the global cooling snap on Earth many hundreds of thousands of years ago. But it does not save from extinction in our time. The pursuit of their expensive leather, which is used in the manufacture of luxury products: handbags, shoes, belts, etc. - One of the reasons why there is a decrease in the number of animals on Earth.
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, forty-five to forty-seven centimeters in size, they destroy a whole crocodile.
In 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 while this does not save the crocodiles from destruction for the purpose of profit.
Environmental changes are also not the last factor influencing the reduction in the number of populations of various species of crocodiles.
Green Dragon
The fact that the appearance of the crocodile resembles the appearance of a mythical dragon made them heroes of fairy tales and traditions. But, unfortunately, more often than negative heroes. In some cultures, crocodiles are considered sacred animals, symbols of power and strength.
The danger is not all species of animals. The worst ones are Nile and comb. Unlike gavials, who do not attack people at all.
Conclusion
Terrible, toothy, tearing predators. When bitten by a jaw of a crocodile can exert pressure up to 16,400 Newtons. For comparison, the human jaw has a relatively small force of 500 Newtons. This is just one of a huge number of interesting facts about this animal, which, along with a description of the skeleton of a crocodile, with signatures of the names of bones and sections, is available in this article.