Crocodiles of Australia. Saltwater (salted) crocodile
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Australian freshwater crocodile(second name "Johnston's Crocodile" Latin name"Crocodylus johnstoni") is a species of reptile of the genus Crocodiles from the family True crocodiles. This species of crocodile was isolated by Robert Arthur Johnston in the late 19th century and was named after its discoverer.
Appearance of an Australian freshwater crocodile
Freshwater crocodiles are relatively small reptiles. Their body length is on average 2.5 meters, although sometimes there are individuals up to 3 meters in length. Females are noticeably smaller than males; they grow up to 2 meters. The body weight of males is 80–90 kilograms, and that of females is only 40–50 kilograms. The scales of these crocodiles are very large and have different shape, for example, on the sides and legs - round, and on the back - triangular. The Australian freshwater crocodile is brown or light brown in color. There are stripes of black or dark brown throughout the body. The belly is dirty yellow or light brown (always lighter than the back and legs).
Australian freshwater crocodiles have a very narrow snout and rather weak jaws. The mouth contains incredibly sharp teeth, the number of which ranges from 68 to 72 pieces. This narrow snout, unusual for crocodiles, helps Johnston's crocodiles find food. These reptiles feed mainly on medium-sized fish. These crocodiles live no more than 50 years. Maximum size reach by the age of 25.
Nutrition
Freshwater diet crocodiles mainly consists of fish, but when there is a lack of it, reptiles also prey on small ungulates, invertebrates, bird reptiles and others. When the dry season begins in Australia, crocodiles “go on a diet”, they are able for a long time live without food. When hunger becomes unbearable, Johnstvon's crocodiles begin to hunt their brothers, who are inferior in size and strength. With the onset of the rainy season, crocodiles again switch to feeding on fish. This species of crocodiles has one remarkable feature.
During the hunt, he is able to remain completely motionless for a long time, waiting for the victim. Its dark color and immobility make the reptile completely invisible near the shore. From the outside it may seem that there is an ordinary log lying in the water. But if, for example, a wild boar approaches this log, then the throw will follow immediately, and after a few seconds the animal will disappear under the water.
Habitat
The Australian freshwater crocodile can only be found on the mainland of Australia (as reflected in the name of the species), and even then not throughout its entire territory. The largest concentration of crocodiles is located in the northern part of the continent, slightly fewer individuals live in the western part. In total, there are no more than 100,000 freshwater crocodiles in Australia. This species of crocodiles is called “freshwater” because it lives exclusively in reservoirs with fresh water(rivers, streams, lakes, swamps, water meadows). It was no coincidence that crocodiles chose fresh water bodies, since their main competitor and enemy, the saltwater crocodile, does not like to settle in fresh water, preferring sea salt water.
Danger!!!
Australian freshwater crocodiles pose a fairly serious danger to humans. In Australia, cases of crocodiles attacking people are very common. Most often, attacks occur during periods of drought, when these reptiles are very hungry and angry. Only a very large individual can kill a person; smaller representatives of the genus are not able to cope with a person.
In addition, their weak jaws do not allow them to bite through a human limb. However, the sharp teeth leave deep wounds on the body. It is very difficult to notice a freshwater crocodile from afar, especially if it is lurking near the shore waiting for prey. The crocodile is also dangerous on land, as it can run fast.
Titles: Australian narrow-snouted crocodile, Johnston's crocodile, freshwater crocodile, Johnston's river crocodile (Australian freshwater crocodile).
Johnston's Australian crocodile - named after Johnson, the first European discoverer, who reported the discovery of a new species to the natural scientist Krefft. The latter is responsible for the misspelling of the researcher's name, which should have been rendered as "johnsoni". Currently, in scientific practice, both the true and erroneous Latin name of the species is used.
Area: Australian freshwater crocodiles are endemic to Australia. Their range covers Northern Australia: they are found in the Northern Territory, Queensland and Western Australia.
Description: Australian freshwater crocodiles have strong feet with clawed, webbed toes. The tail is very powerful. The scales are large, on the sides and on the legs from the inside, round in shape, densely located. The crocodile's muzzle is unusually narrow and pointed in shape, bordered by a row of sharp teeth. This species catches fish easily, so this shape of the muzzle arose during evolution as an adaptation to feeding only on fish. The total number of teeth is 68-72, of which 5 are premaxillary, 14-16 maxillary and 15 mandibular teeth. The fourth tooth on both sides of the lower jaw is larger than the others and can be clearly visible even when the mouth is closed. The eyes have a special transparent eyelid (nictitating membrane) that protects them when the crocodile is under water.
Color: The color is light brown with dark stripes around the body and tail, the pattern of stripes is broken on the neck. Some individuals have clearly visible light brown stripes and spots on the face. Subspecies are unknown, although lighter and darker color phases have been identified, as well as isolated dwarf individuals that reach sexual maturity at half their normal length. Freshwater crocodiles have darker colors compared to common crocodiles. Dwarf individuals reach a length of up to 1.5 m. The existence of dwarf individuals is explained by evolution during natural selection, caused by the need to obtain food in the upper reaches of rivers, where larger individuals cannot penetrate. Genetic studies of the dwarf race do not find any exceptional changes that could serve as a basis for identifying it as a separate subspecies.
Size: Australian freshwater crocodile - relatively small crocodile. The species is characterized by sexual dimorphism, which is expressed in the fact that males are slightly larger than females. Males reach a maximum length of 2.4-3 m, and females - 2.3 m. In nature, the size of males rarely exceeds 2.5-3 meters in length. Females reach sizes of 2-2.1 meters.
Weight: Males weigh up to 90 kg, and females weigh up to 45 kg.
Lifespan: Maximum lifespan is about 50 years.
Habitat: The freshwater crocodile lives in a variety of freshwater bodies of water: swamps, lakes, lagoons and rivers (preferring their mouths, it is less common in the upper reaches of rivers and streams). It has never been found near the coast, in waters with high salinity and where it may encounter the more aggressive saltwater crocodile. It has been noted that if the population saltwater crocodile begins to decline, the population of freshwater crocodile increases, and then Johnston's crocodiles occupy the favorite habitats of their food competitor and appear near the coast. As the saltwater crocodile population recovers, the situation returns to its original position.
Enemies: Sandy (Varanus gouldi) and Argus monitor lizards (Varanus panoptes) as well as wild pigs (Sus scrofa)- the main predators that hunt the eggs of the Australian crocodile during the entire period of their incubation. Thanks to their sensitive sense of smell, monitor lizards easily find crocodile nests in which eggs were laid even 24-48 hours ago. By the time the crocodiles hatch, only a third of all nests usually remain untouched.
Hunting for local residents does not bring great harm for a population of a given species. The young may be killed by the adult reptiles when they are short of food. Crocodiles can also be eaten by black kites, and even large fish. Recently, young freshwater crocodiles have faced a direct threat from the aggressive aga toad (Bufo marinus).
Food: The diet of an adult freshwater crocodile consists mainly of fish. Some species of invertebrates and small vertebrates supplement the diet. Adult crocodiles hunt land animals, waiting for them at the water's edge. They also hunt underwater. During the dry season, due to lack of food, crocodiles practically do not eat, but they can eat other, smaller individuals of crocodiles.
Behavior: Australian crocodiles are one of several species that can gallop on land, reaching speeds of 18 km/h. When hunting, these reptiles use the ambush method, followed by quickly capturing prey by the head or across the body. They are not fussy, they slowly creep up to their prey, leaving only their nostrils, eyes and ears above the water.
Most often, crocodiles dive in the morning (from 6 to 12 noon), but at night they are less active and mostly stay near the surface of the water. The duration of stay under water decreases with increasing body temperature. The maximum duration of the dive was 119.6 minutes, but the largest share in the behavior of this species consists of jumping into the water for relatively short and shallow dives (lasting no longer than 45 minutes and to a depth of at least 40 cm).
Social structure: Leads a solitary life.
Reproduction: Female freshwater crocodiles dig nest-burrows in the sand 10-15 m from the shore. Eggs are usually laid at night to a depth of 12-20 cm, four to six weeks after the mating season. Females instinctively choose a place for the nest so that during rains the eggs will be above the water and not flooded. At the same time, too shallow a clutch depth increases the risk of overheating of the eggs. Once every few years, abnormal conditions occur in the nesting areas of Australian crocodiles. natural phenomena, when the rainy season begins quite early, due to which almost all nests are destroyed by flooding.
Studies have shown that all females of one population lay eggs quite amicably, usually within a three-week period. They can lay clutches close to each other, and in some cases, females even dig up the eggs of their predecessor and lay their own in this place. The latter happens when there are too many masonry in one place.
Before the birth of the cubs, the female digs up a nest, and after their birth carries the newborns in her mouth into the water. The female remains near the young and guards them for some more time.
All crocodiles swallow stones for better digestion, and to quench their thirst they use only freshwater, not seawater.
Breeding season/period: Mating season and courtship are confined to the beginning of the dry season (May), and breeding and nest building continues until July-September.
Puberty: Females reach 11-14 years, males - 16-17 years, reaching a length of 1.5 m.
Incubation: Lasts 6-10 weeks (according to other sources - 75-85 days, depending on temperature).
Offspring: For normal incubation of eggs, a temperature of 30-33"C is required. There are usually 13 eggs in a clutch (sometimes from 4 to 20). Temperature affects percentage birth of females and males: so at temperatures up to 32 "C more males, above 32"C - females.
Females care for their young, but not for as long as the saltwater crocodile. A disturbed female may leave her nest and offspring. It has been established that cubs can be born even in the absence of outside help. Newly hatched crocodiles first absorb the yolk from their sac, which they feed on for several days.
In case of lack of food, cases of cannibalism often occur among crocodiles. Only 1% of all newborn crocodiles survive to reach sexual maturity. Babies eat small prey, such as insects, small aquatic and semi-aquatic arthropods, crustaceans and some fish. 
Benefit/harm for humans: The local population uses crocodiles for meat, eggs and the production of crocodile skin products. Aboriginal harvesting of freshwater crocodiles did not have a noticeable effect on population numbers. However, since the 1950s. Johnston's crocodile skin attracted the attention of industrialists and the population began to decline until the 1960-70s, when measures were taken to protect the species. This species was less subject to extermination as a result of hunting than the saltwater crocodile, since the skin of the former is less suitable for dressing.
There are known cases of freshwater crocodiles attacking people.
Population/Conservation Status: Population 50,000-100,000 individuals. Her condition is believed to be stable. The main reason The decline in the number of Australian freshwater crocodiles is due to the degradation of their usual habitats. Crocodile farms have been created, but they are not widespread.
The species is listed in Appendix II of the CITES Convention and the International Red Book under the category: LRlc (low risk).
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). Although the error was corrected some time later, both names appear in the literature.
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Security status Least Concern IUCN 3.1 Least Concern: |
Appearance
This is a relatively small species of crocodiles - males very rarely grow more than 2.5-3 m, and it takes 25-30 years to reach this size. Females are usually no more than 2.1 m. In areas such as Lake Argyll and National Park Nitmilek previously encountered individuals up to 4 meters in length. The snout is unusually narrow, with sharp teeth. The number of teeth is 68-72, there are 5 premaxillary teeth on each side of the jaw, 14-16 maxillary teeth, 15 mandibular teeth. The color is light brown with black stripes on the back and tail, the belly is lighter. The scales are quite large, round in shape on the sides and outer sides of the paws.
Lifestyle
Like all narrow-snouted crocodiles, the main diet of this species is fish. Additionally, adults may feed on amphibians, birds, small reptiles and mammals. Usually the crocodile sits and waits until the prey comes close enough, and then grabs it with a quick movement of its head. During the dry season, its activity decreases significantly due to lack of food and lower temperatures. The freshwater crocodile is considered harmless to humans. Although it can bite when threatened, its jaws are usually not strong enough to inflict fatal injuries on an adult.
Reproduction
Eggs are laid in July-September, when the water level in the river drops sharply, 6 weeks after mating. Females of the same population, according to research, lay eggs in the same three-week period. They dig holes on the river bank, often very close to each other, and lay eggs at a depth of 12-20 cm. One female lays from 4 to 20 eggs. The incubation period ranges from 65 to 95 days depending on incubation conditions (usually about 75-85 days). At a temperature of about 32 °C, males develop; females develop 2 degrees above or below this value. However, with significant temperature fluctuations, cubs of different sexes can hatch from the same clutch.
About 2/3 of the nests are destroyed by monitor lizards, Australian crows and wild pigs, which manage to seize the moment when their parents leave them unprotected. In some years, the rainy season comes very early, and as a result, all nests can be flooded. If the clutch is preserved, at the end of incubation the female hears the call of the hatching crocodiles, digs up the nest and takes them to the water. However, sometimes crocodiles can hatch and get to the water without the help of their parents. The father guards the offspring for some time, although not as long as is observed in the saltwater crocodile. Therefore, monitor lizards, other crocodiles and Australian ravens prey on young crocodiles.
Population
The freshwater crocodile lives in the northern regions of Australia: in the states
My first such close acquaintance with cold-blooded animals took place in Thailand, in the tourist city of Pattaya. It was in this city that I visited a crocodile farm. In addition to meeting the animals, I also went to their show program. It turns out to be “toothy” trainable and can carry out a wide variety of commands from their trainers.
Where do crocodiles live?
If speak about Thailand, then representatives of aquatic fauna can be found on wetlands of rivers and lakes on the mainland of the country. Average age The reptiles here are 100 years old. As for their size, they grow throughout their lives. Imagine every year after floods, hundreds of crocodiles are thrown out of their usual habitats. After which the “crushers” go on a “free” swim. Therefore, after the floods, you should know that crocodiles can be found anywhere. But it is not at all necessary to go to swampy rivers to get acquainted with crocodiles, and all because you can see crocodiles on special farms. The crocodile farm in Pattaya is located within the city. I went to the farm on an excursion program, which, by the way, was free. The territory where crocodiles live is more like a park, in which, in addition to crocodiles, you can see beautiful garden trees, incredibly beautiful ancient stones, pools with fish and even enclosures with other animals. Crocodiles live in lakes fenced with a metal enclosure. What crocodiles can be seen in the territory:
- combed;
- Siamese;
- gavial.
By the way, the last type of reptile does not pose a threat to humans. Also, it is in this country that it is forbidden to sell bags, wallets, key rings made from the skin of this crocodile... Yes, I almost forgot, crocodiles on this farm, for a fee, Can feed the chicken. I recommend checking your reaction!!! The chicken is tied to a rope and you need to try to tease the “toothy one”. Make him click his teeth for the first, and maybe even the second time, before he has time to eat the chicken. Adrenaline, emotions just go through the roof!!!
Character of a crocodile
It turns out that crocodiles are very smart animals. They cannot be called a thoughtless colossus, in whose head the goal is to kill and eat. Main character traits:
- pliable;
- communicable;
- emotional;
- extrovert.
Besides, crocodilesknow how to trust. Naturally, not to everyone passing by, but, for example, to your trainer. A person who loves an animal and treats it with respect.
What irritates the psyche of crocodiles
Reptiles, it turns out, do not tolerate foreign odors well. Therefore, before each entry into a room with crocodiles, the trainer must pour water on yourself. Otherwise, you can become lunch or dinner for the animal.
Crocodile from the north of Australia
At the end of the 18th century, a certain man named Johnston informed the famous Australian scientist Gerard Krefft (a native of Germany) about the existence of interesting narrow-snouted crocodiles in the north of Australia. The naturalist managed to compose scientific description this species of reptile, since in those years their population was numerous, and catching several individuals for research was not difficult.
When J. Krefft compiled a scientific description of a new species in 1873, he decided to assign it a binomial name in honor of the same Johnston, but made a spelling mistake when writing the surname, calling the species “johnsoni” instead of “johnstoni”. For many years, the reptile was listed in scientific sources under this name, until, while studying the scientist’s manuscripts, the above error was accidentally discovered.
The scientific world decided to leave the binomial name of the crocodile unchanged, but in some sources, however, this reptile is mentioned under the name Crocodylus johnstoni.
Among the popular names of the crocodile, the most commonly used are Australian narrow-snouted crocodile, Australian freshwater crocodile, Johnston's crocodile. Australians often use colloquial speech The name is Freshie, or they simply call him a freshwater crocodile. Why freshwater? Yes, because the range of this reptile intersects with the range of the formidable saltwater crocodile, which is often called saltwater crocodile for the development of sea and ocean salinity waters.
The Australian narrow-snouted (freshwater) crocodile is endemic northern regions Australia, and is found in the states of Queensland, Western Australia and the Northern Territory. It can be found in freshwater swamps, streams and slow-water rivers. This reptile avoids salty and even brackish waters of estuaries and tidal zones.
The narrow-snouted crocodile of Australia does not reach extraordinary sizes - the maximum length of individual individuals is just over three meters (with a weight of up to 100 kg). Record females can grow just over two meters in length and weigh about 40 kg. There is information about the capture of individual individuals up to 4 meters in length, but this has not been confirmed.
Information about the life expectancy of these reptiles differs somewhat in different sources.
IN Australia Zoo lives a narrow-snouted crocodile whose age is estimated at almost 140 years. It is believed that this is the most old crocodile in the world. Australians lovingly call him "Mr Freshy". Mister Fresh has quite a colorful pedigree and life story. In childhood and youth, this reptile was considered a sacred animal, worshiped by the Aboriginal tribe on the Cape York Peninsula (Queensland, Northern Australia). This peninsula is peculiar and unique nature reserve, one of the last remaining undeveloped areas on Earth. The local population here consists mainly of Australian Aborigines.
Then poachers made an attempt on Mister Freshie's life, and he miraculously escaped, losing one eye due to a bullet wound. However, he survived, and since 1970 he has become a pet of the zoo, where he still lives safely.
It is believed that this crocodile was born in 1875. How reliably the age is determined is unknown (there are some doubts among scientists), however, such a longevity of the reptile is impressive.
According to other sources, Australian narrow-snouted (freshwater) crocodiles live in wildlife up to 30 years old.
The appearance of Frechie crocodiles is characterized by a very narrow muzzle, light brown body color and the presence of transverse dark stripes on the body and tail. The belly is lighter colored. Skin bone plates are relatively large and round in shape. The teeth are sharp, awl-shaped, their number in the mouth of a crocodile is 68-72.
Like all narrow-snouted crocodiles, as well as the gharial, the Australian freshwater crocodile feeds primarily on fish. The narrow snout and sharp teeth make it easy to capture fish with lateral movements of the head. However, this predator can also eat other prey - various aquatic animals (amphibians, amphibians), birds, rodents. Even kangaroos were found in the stomachs of these reptiles.
It prefers to hunt from ambush, waiting motionless for prey for a long time, hiding its body under water and exposing only its nostrils and eyes.
During the dry, cool season, these reptiles lose activity and hardly feed.
The Australian narrow-snouted crocodile reproduces by oviposition, and the eggs are laid not in a nest of a structure typical for other crocodiles (from plants and soil), but in burrows that are dug in the sand near the water. At the end of oviposition, the entrance to the hole is covered with sand. Egg laying occurs from July to September, the incubation period is up to three months. 
The female does not guard the clutch as jealously as most known representatives of this order of reptiles, however, she shows some care for the offspring - she helps the brood get out of the nest-burrow and for some time protects the young from enemies. Sometimes the male takes on this responsibility, but it happens that newborns begin life path without the help of parents.
For humans, this small crocodile is considered not dangerous, but there are a few known cases of a crocodile biting people with its sharp teeth. Most often this happens when the reptile is “driven into a corner”, cutting off its escape route. Like all predators, in such cases the Australian narrow-snouted crocodile can become aggressive.
Usually, this animal prefers to avoid meeting people, unlike the extremely dangerous saltwater crocodile.
The skin of freshwater crocodiles was the subject of hunting for hunters and poachers until the 70s of the last century, but then a ban was imposed on all kinds of catching of these reptiles. Currently, crocodiles are raised on special farms for the leather goods industry.
Thanks to environmental measures, the population remains stable, but there is a decrease in the average size of individuals, which is caused (according to scientists) by deteriorating living conditions (pollution and environmental disturbance). Conservation status kind Crocodylus johnstoni- causing the least concern.
