Nile crocodile (Crocodylus niloticus). Anatomical structure of a crocodile How long does a Nile crocodile live?

CROCODILE
Squad CROCODILES(Crocodylia) - a family of reptiles. There are three species living in Africa. The narrow-snouted crocodile is endemic to Africa. Lives in everyone large rivers West Africa, Lake Tanganyika and the east of the mainland. Blunt (or dwarf) crocodile - in central Africa. Nile crocodile - on the mainland and some islands.

Crocodiles occupy a special position among modern reptiles, being closer relatives of the extinct dinosaurs, which survived by almost 60 million years, and modern birds than other reptiles of our time. A number of features of the organization of crocodiles, and first of all the perfection of the nervous, circulatory and respiratory systems, allows us to consider them the most highly organized of all living reptiles. The evolution of crocodiles, starting with the appearance of this group about 150 million years ago, went in the direction of increasing adaptation to water image life and predation. The fact that crocodiles have survived to this day is often explained by their life in various fresh water bodies of tropical and subtropical zones, that is, in places where conditions have changed little since the appearance of crocodiles.

The general body shape of the crocodile is lizard-shaped. They are characterized by a long, laterally compressed, high tail, membranes between the toes of the hind limbs, a long muzzle and a head flattened in the dorso-ventral direction. The forelimbs have five fingers, the hind limbs have four (there is no little finger). The nostrils, located at the front end of the muzzle, and the eyes are raised and located on the upper side of the head, which allows crocodiles to stay in the water near its surface, exposing only the eyes and nostrils to the air. The external auditory openings are closed with movable valves that protect the eardrums from mechanical damage when immersed in water. The body, tail and limbs of crocodiles are covered with large, regular-shaped horny scutes located on the back and stomach in regular rows. In the inner layer of skin (corium) under the horny scutes of the outer layer on the back and in some species on the belly, bone plates (osteoderms) develop, firmly connected to the horny scutes, forming a shell that well protects the crocodile’s body; on the head, osteoderms are fused with the bones of the skull.

Modern crocodiles inhabit various fresh water bodies. Relatively few species tolerate brackish water and are found in river estuaries (African narrow-snouted crocodile, Nile crocodile, American sharp-snouted crocodile). Only saltwater crocodile swims far into the open sea and has been observed at a distance of 600 km from the nearest shore. Crocodiles spend most of the day in the water. They go out to the coastal shallows in the morning and in the late afternoon to warm up in sun rays.

Crocodiles hunt at night. Fish is an essential component of the diet of all crocodiles, but crocodiles eat any prey they can handle. Therefore, the set of foods changes with age: various invertebrates - insects, crustaceans, mollusks, worms - serve as food for the young; larger animals hunt fish, amphibians, reptiles and water birds. Adult crocodiles are able to cope with large mammals. There is a known case of the remains of a rhinoceros being found in the stomach of a Nile crocodile. Many species of crocodiles exhibit cannibalism - the devouring of smaller individuals by larger individuals. Crocodiles often eat carrion; some species hide the uneaten remains of the prey under an overhanging bank and later devour them half-decomposed. Crocodiles move in the water with the help of their tail. On land, crocodiles are slow and clumsy, but sometimes make significant journeys, moving several kilometers away from bodies of water. When moving quickly, crocodiles place their legs under their body (usually they are widely spaced), which rises high above the ground. Young Nile crocodiles can gallop at a speed of about 12 km per hour. Crocodiles lay eggs the size of chicken or goose eggs, covered with a calcareous shell. Number of eggs in clutch different types there are from 10 to 100. Some species bury their eggs in the sand, others lay them in nests made by the female from rotting vegetation. The female remains close to the clutch, protecting it from enemies. Young crocodiles, still inside the eggs, make croaking sounds at the time of hatching, after which the mother digs up the clutch, helping the offspring get out.

Crocodiles grow rapidly in the first 2-3 years of life, during which they reach crocodiles and gharials. sizes 1-1.5 m. With age, the growth rate decreases, and they add only a few centimeters in length per year. They reach sexual maturity at the age of 8-10 years. Crocodiles live up to 80 - 100 years. Adult crocodiles have few enemies, if you exclude humans. There have been cases of attacks by elephants and lions on crocodiles traveling overland from one body of water to another.

Widely distributed in Africa Nile Crocodile (Crocodylus niloticus). It can be found throughout Africa, except its northern part, in Madagascar, Comoros and Seychelles. Most often it settles outside the forest, but also enters forest reservoirs. Reaches a length of 4-6 m. The cubs that have just hatched from eggs have a length of about 28 cm, by the end of the first year of life they reach 60 cm, by two years - 90 cm, at 5 years - 1.7 m, at 10 years - 2, 3 m and at 20 years old - 3.75 m. They spend the night in the water, and at sunrise they go out to the shallows and bask in the sun's rays. The midday, hottest hours are spent in water, with the exception of cloudy days. In windy or inclement weather, they spend the night on the shore. The maximum duration of stay under water for animals about 1 m long is about 40 minutes; larger crocodiles can stay underwater for much longer. The food of the Nile crocodile is very varied and changes with age. In cubs up to 30 cm long, 70% of their food consists of insects. Larger individuals (about 2.5 m long) feed on fish, mollusks, crustaceans, and even larger ones feed on fish, reptiles, birds and mammals. Adult Nile crocodiles can attack large mammals such as buffalos and even rhinoceroses. Crocodiles lie in wait for animals near watering places, in water or on land in thick grass. In a number of areas, Nile crocodiles are dangerous to humans. Eggs are always laid in the dry season, when water levels are low. Females dig a hole in the sand up to 60 cm deep, where they lay 25-95 (on average 55-60) eggs. Incubation lasts about 90 days, during which the mother remains constantly at the nest, guarding the clutch. Apparently, the animal is not feeding at this time. By the time they hatch, the young crocodiles inside the eggs begin to make grunting sounds, which serve as a signal for the mother, who helps the cubs get out from under the sand and accompanies them to the water. At this time, the female can attack a person even on land. Hatching from eggs usually occurs after the first rains fall, with a rise in the water level in lakes and rivers, so that young crocodiles immediately find shelter and food in flooded reservoirs. After the young crocodiles emerge from the eggs, the mother leads them (according to Cott's observations) to the "nursery" she has chosen - a shallow pond protected by vegetation. Here young crocodiles stay for about six weeks; all this time the mother remains with the brood, protecting it from attacks by predators. In the absence of a mother, crocodiles hatched from eggs often remain close to the nest, where they are usually exterminated by predators - goliath herons, marabou, kites. Numerous cases of cannibalism (devouring eggs and young individuals) are known, which is usually considered a mechanism for regulating the number of the species: it is noted that cannibalism occurs more often, the higher the number of crocodiles. The number of Nile crocodiles has fallen everywhere and continues to fall. IN ancient Egypt crocodiles were revered as sacred animals; now they are almost exterminated. The same fate will befall crocodiles in a number of places in Central and East Africa if measures are not taken to protect the species

Crocodile animal reptile, part of the order of aquatic vertebrates. These animals appeared on Earth more than 200 million years ago.

The first individuals first lived on land and only later mastered aquatic environment. The closest relatives of crocodiles are considered.

Features and habitat of the crocodile

Life in water has formed the corresponding body of a reptile: the body of crocodiles is long, almost flat, with a flat long head, a powerful tail, short paws with toes connected by membranes.

Crocodile is a cold-blooded animal, his body temperature is about 30 degrees, sometimes it can reach 34 degrees, it depends on the temperature environment. Animal world crocodiles very diverse, but the species differ only body length, there are reptiles up to 6 meters, but most are 2-4 m.

The largest saltwater crocodiles weigh more than a ton and have a length of up to 6.5 m, they are found in the Philippines. The smallest land crocodiles, 1.5-2 m, live in Africa. Under water, the crocodile's ears and nostrils close with valves, transparent eyelids fall over the eyes, thanks to them the animal sees well even in muddy water.

The mouth of crocodiles does not have lips, so it does not close tightly. To prevent water from entering the stomach, the entrance to the esophagus is blocked by the velum palatine. The crocodile's eyes are located high on the head, so only the eyes and nostrils are visible above the surface of the water. The brown-green color of the crocodile camouflages it well in the water.

Green tint prevails if the ambient temperature is elevated. The animal's skin consists of durable horny plates that protect the internal organs well.

Crocodiles, unlike other reptiles, do not shed; their skin constantly grows and renews itself. Thanks to its elongated body, the animal maneuvers well and moves quickly in the water, while using its powerful tail as a rudder.

Crocodiles live in fresh waters of the tropics. Eat species of crocodiles, well adapted to salt water, they are found in coastal strip seas - these are combed, Nile, African narrow-snouted crocodiles.

Character and lifestyle of a crocodile

Crocodiles are almost constantly in the water. They crawl ashore in the morning and evening to warm their horny plates in the sun. When the sun is hot, the animal opens its mouth wide, thus cooling the body.

Birds, attracted by leftover food, can freely enter the mouth at this time to eat. And although crocodile predator, wild animal he never tries to grab them.

Crocodiles mainly live in fresh waters, in hot weather, when the reservoir dries out, they can dig a hole at the bottom of the remaining puddle and hibernate. During drought, reptiles can crawl into caves in search of water. If hungry, crocodiles are able to eat their relatives.

On land, animals are very clumsy and clumsy, but in water they move easily and gracefully. If necessary, they can move to other bodies of water by land, covering several kilometers.

Nutrition

Crocodiles hunt mainly at night, but if prey is available during the day, the animal will not refuse to feast on it. Receptors located on the jaws help reptiles detect potential prey even at a very long distance.

The main food of crocodiles is fish, as well as small animals. The choice of food depends on the size and age of the crocodile: invertebrates, fish, amphibians are preferred for young individuals, but not for adults. large mammals, reptiles and birds.

Very large crocodiles can easily handle victims larger than themselves. This is how Nile crocodiles hunt during their migration; the saltwater crocodile hunts livestock during the rains; Madagascar can even eat.

Reptiles do not chew food; they tear it into pieces with their teeth and swallow them whole. They can leave prey that is too large at the bottom to soak. Stones swallowed by animals help in digesting food; they crush it in the stomach. Stones can be of impressive size: a Nile crocodile can swallow a stone up to 5 kg.

Crocodiles do not eat carrion unless they are very weak and unable to hunt; they do not touch rotten food at all. Reptiles eat quite a lot: they can consume about a quarter of their weight in food at a time. About 60% of the food consumed turns into fat, so the crocodile can fast for up to one year if necessary.

Reproduction and lifespan

The crocodile is one of the long-lived animals, he lives from 55 to 115 years. Puberty it occurs early, at about the age of 7 - 11 years. Crocodiles are polygamous animals: a male has 10 - 12 females in his harem.

Although the animals live in water, they lay eggs on land. At night, the female digs a hole in the sand and lays about 50 eggs there, covering them with leaves or sand. The size of the depression depends on the illumination of the place: in the sun the hole becomes deeper, in the shade it is not very deep.

The eggs mature for about three months, during which time the female remains close to the clutch, practically not feeding. The sex of future crocodiles depends on the environmental temperature: females appear at 28-30° C, males at temperatures above 32° C.

Before they are born, the babies inside the eggs begin to grunt. The mother, hearing the sounds, begins to dig out the masonry. Then he helps the babies free themselves from the shell by rolling the eggs in their mouths.

The female carefully transfers the emerging crocodiles, measuring 26-28 cm, into a shallow body of water, capturing them in her mouth. There they grow for two months, after which they disperse to the surrounding, not heavily populated, reservoirs. Many small reptiles die, they become victims of birds, monitor lizards and other predators.

Surviving crocodiles first feed on insects, then hunt small fish and, from 8-10– summer age They begin to catch larger animals.

Not everyone is a danger to humans species of crocodiles. So the Nile crocodile and the saltwater crocodile are cannibals, but the gharial is not at all dangerous. Crocodile as a pet Today they are even kept in city apartments.

In their habitats, crocodiles are hunted, their meat is eaten, and their skin is used to create haberdashery, which has led to a decline in the crocodile population. In some countries today they are bred on farms; in many tribes they are considered crocodile sacred animal.

The Nile crocodile is large reptile, which belongs to the family of true crocodiles, lives in Africa and is an integral link in aquatic and semi-aquatic ecosystems there. It is larger than most other crocodiles and is the second largest member of this family after the saltwater crocodile.

Appearance

The Nile crocodile has a squat body of a highly elongated format, which turns into a thick and strong tail, tapering towards the end. Moreover, the length of the tail can even exceed the size of the body. The strongly shortened powerful legs of this reptile are spaced widely - along the sides of the body. The head, when viewed from above, has the shape of a cone slightly tapering towards the end of the muzzle, the mouth is large, equipped with many sharp teeth, total quantity of which there can be 68 pieces.

This is interesting! In crocodile cubs that have just hatched from eggs, you can notice a skin thickening on the front of the muzzle that looks like a tooth. This seal, called an “egg tooth,” helps hatchling reptiles break through the shell and quickly emerge from their eggs.

The color of Nile crocodiles depends on their age: young individuals are darker - olive-brown with a cross-shaped black shading on the body and tail, while their belly is yellowish. With age, the skin of reptiles seems to fade and the color becomes paler - grayish-green with darker, but not too contrasting stripes on the body and tail.

The crocodile's skin is rough, lined with rows of vertical scutes. Unlike most other reptiles, the Nile crocodile does not shed, since its skin tends to stretch and grow along with the animal itself.

Lifestyle

The Nile crocodile cannot be called a herd animal, but they live in large groups and often hunt in groups. At the same time, a strict hierarchy is observed in each group, which does not lead to conflicts. The largest individuals always dominate in groups.

But group hunting does not take place so often; more often individuals lead a solitary lifestyle. At dawn, the Nile crocodile comes out onto the coastal sand and dries in the sun, while its mouth is usually open at this moment. Having warmed up in the sun, the crocodile returns to the pond to hunt around noon. Since the Nile crocodile can eat quite a lot, it hunts almost every day, but in those cases when it is not hungry, then at lunch it can either simply swim around the perimeter of its area or remain on coastal zone half asleep. It is impossible to say that a crocodile ever completely falls asleep, since thanks to its sense of touch, it always feels everything that happens around it.

When a group of crocodiles is resting on the same beach, the dominant (i.e. larger) individuals are always in the most convenient places, and the distance between each crocodile is quite respectful. At sunset, the Nile crocodile always returns to the pond for hunting, which continues throughout the night and early morning. Thus, individuals of the Nile crocodile lead predominantly night look life.

Nile crocodiles most often hunt for fish, but often swamp and water birds, small and large mammals that come to the pond where the crocodile lives to drink become prey. The Nile crocodile waits for its prey, completely immersed in the water and leaving only its eyes, nose and ears on the surface. It is capable of completely silently and imperceptibly swimming up to its prey at a sufficient distance, and then, in a sharp jump, grab the prey by the throat and also quickly drag it under water.

Underwater, a crocodile either strangles its prey or waits for it to choke. There have been cases when crocodiles left their prey under water for some time, placing it between the roots of trees, or in crevices so that the meat softened.

If the prey managed to avoid the attack of the crocodile, then it will not pursue it on land. It was extremely rare for crocodiles to rise more than halfway out of the reservoir while feeding. Crocodiles will also not hunt on the shore. Crocodiles can eat prey that is already dead, but they avoid meat in which the process of rotting has already begun.

The crocodile most often kills the fish with blows of its tail, after which it swallows it. When hunting in groups, several crocodiles drive fish into schools, where they have the opportunity to stun more production In this case, the larger individuals swallow the prey first, and their small relatives can only collect the remains of the dominant individuals.

Acoustic communication between individuals consists of a fairly extensive set of sound signals. Sounds always accompany mating tournaments. In addition, a characteristic dull moo can be heard when an individual is restless. An angry crocodile makes sounds similar to hissing sniffles. Young, newly hatched individuals make loud croaking sounds.

In general, the behavior of the Nile crocodile can be characterized as individual and social. He can manifest himself both in groups and alone. There is even a certain semblance of intelligence in it, and therefore cunning moves during the hunt are possible, as well as the ability to guard and protect the offspring, which is not typical of most other reptiles.

The Nile crocodile has the reputation of a cannibal, because due to carelessness, according to information from various sources, several hundred people become victims of crocodiles in their habitats every year. However, there are no official statistics to confirm or deny this information impossible.

Habitat of the Nile crocodile

The Nile crocodile lives throughout almost the entire African continent.

In ancient times, the Nile crocodile was found in Israel, Palestine, Lebanon, Algeria, Libya, Jordan, Syria and the Comoros Islands.

Now its habitat has shrunk slightly. Most individuals of the Nile crocodile live in Zambia, Ethiopia, Kenya and Somalia in the Nile basin. A smaller number of individuals live in Zanzibar, Morocco, Tanzania, Congo, Senegal, Sierra Leone, Uganda, Rwanda, Kenya, Liberia, Mozambique, Mauritania, Nigeria, Namibia, Malawi, Zaire, Botswana, Cameroon, Angola, Central African Republic, Chad , Burundi, Guinea, Cote d'Ivoire, Swaziland. The Nile crocodile is also found on nearby islands along the coasts of Africa: Madagascar, Socrates Island, Cape Verde Islands, the Sao Tome and Principe archipelago.

Nutrition

The daily menu of a crocodile, like most amphibians, is quite varied. Kids love to eat insects. As they get older, they prefer fish, shellfish and crustaceans. Adults find other prey - reptiles, birds. Sometimes their prey can be a large buffalo, rhinoceros, lion or tiger. Hiding in the water near the shore, they patiently wait for several hours until the animal approaches the shore. Having seen the prey, the predator quietly approaches it, while it unsuspectingly drinks water, it is not visible, because above the water only the eyes and nostrils of the crocodile. Suddenly, jumping out of the water, the crocodile grabs with its strong teeth the victim by the head and immerses him under water. A choking animal becomes easy prey, and the crocodile enjoys it, tearing the victim into pieces with its powerful jaws, therefore, its attack is always a win-win.

An easy prey could be a frivolous monkey jumping from branch to branch, or a bird gaping on the shore or resting on large algae leaves.

Fish, Nile crocodile jams with a strong blow tail along the water surface and immediately easily swallows. They eat often, but due to their slow metabolism, they can go without food for several weeks, and even more than one month.

Surprisingly, crocodiles share prey with their brothers, of course, if they took part in the hunt. Having honestly divided the prey into pieces, the alligators calm down and rest, gaining strength before a new hunt.

Reproduction

IN mating season males become especially aggressive. To attract friends, they snort loudly, roar and slap their muzzles on the surface of the water. Females choose a mate for themselves, swimming to the site of the male they like.

The newly-made spouses joyfully sing unique trills together and prepare for procreation. Having chosen a dry place, the female digs a hole in the sand or soft earth up to 30-45 cm deep. She lays about 50 eggs in it and carefully buries them. During the entire incubation period (85-90 days), she stays close to the clutch, protecting it from uninvited guests. Often, her nearby spouse helps her in protecting her future offspring.

The crocodiles, ready to hatch, squeak pitifully, calling for help from their mother. She carefully digs up the sand and, holding the cubs in her mouth, carefully carries them to the pond.

Newborns weigh about 500 g with a body length of 25-30 cm. They spend the first weeks of their life in shallow water under the close attention of their mother, feeding on insects. At the age of 8 weeks, they split into small groups and look for shelter in the form of burrows, in which they live up to 4-5 years.

By this age, they grow up to 2 m and, no longer fearing enemies, go in search of their own territory. They reach sexual maturity at 12-15 years.

Nile crocodiles and humans

They have few enemies; the greatest danger to crocodiles is humans. They hunt them because crocodiles are quite dangerous predators, and besides, their skin became lately a very valuable product.

As a result of barbaric destruction, there were almost none left on the shores of water bodies in the Middle East. Tropical reservoirs were under threat of existence, because their orderlies - crocodiles - were no longer there. They ate sick and weakened animals that came to the water to drink and lived in it, their remains, trash fish, etc.

Soon, active work began in this direction. The situation is now under control and formidable predators bred on farms specializing in crocodile breeding. In addition, other measures are being taken to restore the number of animals.

The ancient Egyptians worshiped the god of water and the flood of the Nile - Sebek, who was depicted as a living or mummified crocodile or a man with the head of a crocodile. The cult of the Nile crocodile was widespread among the Egyptians: predators were kept as pets, some individuals were decorated with jewelry during life, and after death they were mummified and buried with honors in a sarcophagus.
An amazing fact: hippopotamuses and Nile crocodiles peacefully coexist in the same body of water, and female hippos can leave offspring next to the reptiles for protection from land-based predators.
In accordance with the observations of researchers, an interesting hypothesis has emerged suggesting a symbiosis of Nile crocodiles with certain species of birds - the clawed lapwing and the Egyptian runner, which is also called the crocodile watchman. The Nile crocodile opens its mouth wide, and the birds pick out the remains of meat and leeches from its teeth. But it has not yet been possible to document the truth of such a symbiosis.
The peak of extermination of Nile crocodiles occurred in the mid-20th century, when large aquatic reptiles were killed not only for their skin high quality, but also for the sake of edible meat and internal organs supposedly having healing properties. Then the population of the species was on the verge of extinction. Currently, the Nile crocodile is listed in the Red Book of the World Conservation Union (IUCN).

Nile crocodile (Crocodylus niloticus) The most dangerous crocodiles are the saltwater and Nile crocodile. They account for the most human casualties. You can read more about the saltwater crocodile in this encyclopedia. Now let's get acquainted with the Nile crocodile.

The crocodile is found throughout Africa, Madagascar, Comoros and Seychelles. More recently it was also found in Asia, but today it has been completely exterminated there. There are many species of Nile crocodiles:

East African Nile crocodile
West African Nile crocodile
South African Nile crocodile
Malagasy Nile crocodile
Ethiopian Nile crocodile
Kenyan Nile crocodile
Central African Nile crocodile

These crocodiles are found in freshwater lakes and rivers. They reach a length of 4-6 m, but 7-meter giants are also known. The weight of these animals ranges from 272 to 910 kg.

Their muzzle is not very long, at least not more than wide. Young crocodiles are dark olive and brown in color. The color of an adult crocodile is dark green with black spots on the back, and the belly is lighter than the entire body of the reptile, often dirty yellow. With age, the crocodile becomes paler. Crocodiles' eyes and nostrils are located at the top of their head, so they can see and breathe while the rest of their body is submerged. Unlike other reptiles, crocodiles have external ears that close, as do the nostrils, when crocodiles dive.

The Nile crocodile is a diurnal animal. At night it rests in bodies of water, and at sunrise it begins to hunt, or continues to rest in the sun. The food of the Nile crocodile is quite varied. Small crocodiles feed on insects, such as various dragonflies. Larger individuals - fish, mollusks, crustaceans. Sometimes their prey may be a reptile, bird or mammal, such as buffalo or even rhinoceros. Sometimes crocodiles attack tigers and lions. The crocodile waits for its future prey in the water, near the shore. It may take several hours until any living creature approaches the watering hole. Then the crocodile swims closer to the victim and waits at a distance of just a few meters from it, and at this time the entire body of the crocodile is under water, with the exception of the nostrils and eyes. Suddenly, a crocodile jumps out of the water, grabs the victim’s head with its mouth, drags it into deep water and drowns it. After this, the crocodile tears out pieces of meat with its powerful jaws. When hunting for fish, the crocodile beats with its tail in order to frighten it and stun it, and it swallows the stunned one. Reptiles feed frequently, although they can go without food for several days, sometimes a year or even more.

Crocodiles are perfectly adapted to living in and under water. Crocodiles swim using their powerful paddle-like tail. The hind legs have webs. Another adaptation to life in water is the third eyelid: a membrane that covers the eyes when diving under water - thus protecting the crocodile's eyes from the effects of water without losing the ability to see. Underwater reptiles can be very for a long time: on average, about 40 minutes, and older crocodiles may not surface for more than an hour.

On land, crocodiles are, of course, slower than in water, but they can still reach a fairly decent speed - somewhere up to 30 km/h. However, on land they are very cowardly and try to quickly run away closer to the water. This is why only 3 out of 10 crocodile attacks occur on land.

Crocodiles reach sexual maturity at 8-12 years. The female lays 40-60 eggs. The female spends the entire period of incubation, which lasts 80-90 days, close to the nest, then she helps the newborns get out of the egg. The newborns are carried to the water, with the male and female caring for the offspring together. For two years, the young live next to their mother.

The Nile crocodile, like its relative, the saltwater crocodile, has a reputation as a man-eater; more people than from all other crocodiles. Several hundred people become their victims every year. The following situations are dangerous:

if you are sailing in a boat on a river where Nile crocodiles are found. In 1992, a Nile crocodile attacked a family who were crossing the river in a small boat. The crocodile rammed the boat and, when the people were overboard, he dragged everyone to the bottom one by one. Other people on the shore could not help. And indeed, when a crocodile attacks, it is very difficult to help in any way. Even if you shoot a reptile, there is little chance that the crocodile will die or at least weaken and let go of its victim.
Crocodiles protecting their young offspring are very dangerous. They become very aggressive and desperate. True, the situation is made a little easier by the fact that they try not to move far from young crocodiles, so it is possible to get away from the predator.
A wounded animal is completely uncontrollable. In 1985, an African village was terrorized for several days by a wounded crocodile. He fell into a trap, but managed to escape from it. The injury he received was very painful, so the reptile simply went berserk - it wandered into the settlement and attacked everyone it came across. More than 14 people were injured by his teeth.


	Length: 4-6 m Weight: 272-910 kg Place of distribution: Africa, Madagascar, Comoros and Seychelles.

The Nile crocodile (lat. Crocodylus niloticus) is a large reptile of the family of true crocodiles. The largest of the 3 species of crocodiles found in Africa, and the second largest in the world after the saltwater crocodile. Due to its habitat, size and strength, it is known as a man-eating crocodile and was an object of fear and worship in ancient times. To this day it remains perhaps the most known species crocodiles. In general, the species' numbers are relatively high and stable, although populations in some countries are endangered.

Appearance

Like all crocodiles, the Nile crocodile has short legs located on the sides of the body, scaly skin covered with rows of bony plates, a long strong tail and powerful jaws. The crocodile's eyes are equipped with a third eyelid for added protection and have special glands that allow them to be washed with tears (hence the expression "crocodile tears"). The nostrils, ears and eyes are located at the top of the head, thanks to which the crocodile can almost completely submerge in water, leaving them on the surface.

The coloring of the Nile crocodile also allows it to remain undetected. Juveniles are usually gray or light brown with dark stripes on the back and tail. With age, the color darkens and the stripes become less noticeable. The belly has a yellow tint; this skin is considered to be of the highest quality.

Usually the crocodile crawls on its stomach, but can also walk with its body raised. Small individuals are able to run a short distance at a gallop, developing a speed of 12-14 km/h. It also swims quickly (30 km/h) making sinusoidal movements with its tail.

Physiology

The heart is four-chambered, like a bird's, which allows it to more efficiently saturate the blood with oxygen. Typically, the Nile crocodile dives for 2-3 minutes, but if necessary it can remain under water for up to 30 minutes, and with reduced activity - up to two hours. Being a cold-blooded animal, it has a relatively slow metabolism and can go without food for a long time, but at the same time is able to eat up to half own weight in one sitting.

The Nile crocodile has fairly good hearing and a rich vocal range. Its skin is equipped with special receptors that respond to changes in water pressure. The jaws have impressive strength, which allows them to hold large animals. Typically has 64-68 conical teeth - 36-38 on the upper jaw and 28-30 on the lower jaw. Newly hatched crocodiles have a special tooth-like seal of skin at the front of their snout that helps them escape from the egg.

Dimensions

The Nile crocodile is large in size, usually about 5 m, occasionally up to 5.5 m. Weight often exceeds 500 kg, and there are individual specimens weighing over 1200 kg. The largest known specimen was killed in Tanzania in 1905: length 6.45 m, weight 1090 kg. Reports of 7-meter crocodiles have not been confirmed. On the southern border of the range - in South Africa Nile crocodiles are somewhat smaller in size, their length usually does not exceed 4 m. Like other species of crocodiles, they exhibit sexual dimorphism - females are on average 30% smaller than males. Overall the differences are smaller than in many other species.

Crocodiles living in colder climates, such as southern Africa, are smaller - about 4 m. The dwarf Nile crocodile, living in Mali and the Sahara Desert, grows only to 2-3 m. It is believed that such differences in size are a consequence of worse living conditions, and not genetic differences.

Reproduction

IN normal conditions The Nile crocodile becomes sexually mature by the age of ten, when it reaches a length of 3 m for males, 2-2.5 m for females. During the mating season, males attract females by slapping the water with their snouts, roaring, snorting and making other noises. Large males are usually more attractive to females. During mating games pairs “sing” peculiar trills and rub the undersides of their muzzles.

The time of egg laying largely depends on latitude - in the north of the range it occurs during the dry season, and in the south it is usually tied to the beginning of the rainy season - November or December. In Zimbabwe, females lay eggs in September or early October. Favorite places for building nests - sandy beaches, dry riverbeds and river banks. The female digs a hole up to 50 cm deep two meters from the shore and lays from 20 to 85 eggs (50 on average). Several females may build nests close to each other.

Having laid eggs, expectant mother covers the nest with sand and guards it during the 3-month incubation period. The father is usually nearby too, and both parents will attack anyone who tries to approach the nest. Despite such care, many nests are destroyed by people, monitor lizards and other animals if the mother leaves to hide from the heat or take a dip in the water.

The hatchlings make chirping sounds, and at this signal the mother breaks the nest. Parents sometimes take the eggs into their mouths and squeeze them between the tongue and roof of the mouth to help the offspring release. Then the female takes the crocodiles to the water or carries them in her mouth.

As with other crocodiles, the sex of the young is determined by temperature during the middle third of the incubation period, rather than genetically. If the temperature inside the nest was below 31.7 °C or above 34.5 °C, then females are born, otherwise males.

Newly hatched crocodiles are about 30 cm long and grow quite quickly in the first years. The mother takes care of the offspring for two years. If several nests were close to each other, mothers can jointly care for their offspring, forming a kind of crocodile nursery. Within two years, young crocodiles reach a size of 1.2 m and leave their native places, while avoiding the territories of older and larger crocodiles. Average duration The lifespan of Nile crocodiles is 45 years; there are specimens up to 80 years old.

Nutrition

Newly hatched crocodiles feed on insects and aquatic invertebrates, quickly switching to amphibians, reptiles and birds. The diet of even adult crocodiles consists of 70% fish and other small vertebrates, despite the fact that a crocodile can eat almost any animal that comes to a watering hole, with the exception of adult elephants and hippopotamuses. The Nile crocodile also eats carrion, although it avoids rotten meat. A group of crocodiles can go hundreds of meters from the shore to get to the carcass of a large animal.

An adult crocodile uses its body and tail to push a school of fish towards the shore and eats it with a quick movement of its head. Crocodiles can also form a group and block migrating fish by forming a semicircle across the river. In this case, dominant crocodiles eat first.

It is known that Nile crocodiles can successfully attack zebras, antelopes, buffalos, young hippos and rhinoceroses, giraffes, warthogs, hyenas, monkeys, felids, as well as other crocodiles. The ability to almost completely hide under water in combination with high speed on short distances makes crocodiles good hunters of large prey. They grab her with powerful jaws, drag her into the water and hold her there until she drowns. When the prey is dead, they tear off pieces of it and swallow it. When sharing joint prey, they coordinate efforts to tear the body apart, and can also push it under snags or stones for this purpose.

The Nile crocodile poses a danger to humans, although to a lesser extent than the saltwater crocodile. Females are especially dangerous during the period of caring for offspring, when they become especially aggressive towards any animal approaching the nest. Most attacks occur far from civilization and are not recorded, so the actual number of victims is unknown. According to some sources, it is 1000 people per year, according to others - 200. In 2005, a crocodile was caught in Uganda, which, according to local residents, ate 83 people in 20 years. In 2006, Richard Root, a professor of medicine at the University of Washington, fell victim to a crocodile in Botswana.

The Nile crocodile is believed to have a symbiotic relationship with some birds, such as the clawed lapwing (Vanellus spinosus). According to some reports, the crocodile opens its mouth wide, and at this time the bird takes out pieces of meat stuck in its teeth. However, these reports have proven difficult to verify, and it may not be a truly symbiotic relationship.

Distribution and protection

The Nile crocodile prefers to live along the banks of rivers and lakes and in freshwater swamps, and is sometimes found in brackish water, estuaries or mangroves. It is distributed throughout almost all of sub-Saharan Africa, as well as in Madagascar and the Nile Basin. It once lived much further north - fossil remains of this animal were discovered in Algeria, Israel and Jordan, as well as on the Comoros Islands.

From the 1940s to the 1960s, the Nile crocodile was heavily hunted, mainly for its high-quality skin, less so for its meat and supposed organs. medicinal properties. This led to a multiple reduction in the number of the species, resulting in the threat of its extinction.

The Nile crocodile is widespread in many countries of southern and East Africa, such as Somalia, Ethiopia, Kenya, Zambia, the population size is monitored and documented.

The Nile crocodile is included in the Red List of the World Conservation Union under the category of minimal risk. The crocodile trade is regulated international convention according to Appendix I of CITES.