Crocodile is a reptile of Crocodile and Crocodile,[8]There are 8 genera and 23 species.Crocodile has a long trunk;Muscular development;[9]The head is flat, the head skin is close to the skull, and the skull is firmly connected, unable to move;The teeth are conical and grow in the alveoli, with more than 25 teeth on each side;The tongue is short and flat, and cannot protrude;Eyes are small and slightly protruding;The tail is thick and slightly flat;[10]Short and thick limbs;The outer nostril is located on the back of the tip of the snout, with valves on it;[11]There are armor like scales.[12]
Crocodiles are mostly distributed in tropical areas of Africa, Asia, North and South America and Australia,[13]Only Chinese alligators and American alligators live in temperate regions.[14]Crocodiles live in lakes, marshes, shoals and other areas.Adult crocodiles spend most of their time underwater, sometimes exposing their eyes and nose out of the water;Sensitive hearing and vision;In the afternoon, they will surface to bask in the sun;Frequent night activities;Have dual respiratory system;[15]Common group living together;[16]It likes warm environment.Crocodiles mainly feed on vertebrates, molluscs and crustaceans.[17]Before spawning, crocodiles will go to the shore to build their own "spawning room" with soft things such as leaves and hay, and use the sun's light and the heat of weeds to hatch their eggs,[18]At the age of 12, she began to give birth. Each time she laid 10-90 eggs, it took 84-90 days for hatching.[19]AlligatorFish live 65 years.[20]
Crocodile, as one of the oldest species on the earth so far, retains many characteristics of early dinosaurs and reptiles, also known as "living fossil".[21]Large crocodiles pose a certain threat to human beings and will launch attacks suddenly before human beings respond.[22]There is a western proverb "crocodile tears", which means false compassion. It means that crocodiles will slowly shed water like liquid from their eyes when swallowing larger animals, and it seems that crocodiles are shedding tears of sympathy.[23]Among 23 crocodile species, 13 are included in the Red List of Endangered Species of the World Conservation Union.Siamese alligator is now on the verge of extinction.[24]Chinese alligator is a special crocodile in China, and has been listed as a first-class protected animal in China.[25][26]
Crocodiles live in lakes, marshes, shoals and other areas.Crocodiles live mostly in the tropics, except a few in temperate regionsSubtropical regionRivers, lakes, and wateryswamp, and some live in shoals near the coast.[4][15]
Life habits
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A masterpiece of the British Wildlife Photography Competition: Crocodiles eat turtles brutally
Adult crocodiles spend most of their time underwater, sometimes exposing their eyes and nose out of the water;Sensitive hearing and vision;In the afternoon, they will surface to bask in the sun;Frequent night activities;Have dual respiratory system;[15]Common group living together;[16]It likes warm environment.Crocodiles mainly feed on vertebrates, molluscs and crustaceans.[17]
Crocodiles often give people the illusion of being sluggish.Others describe that crocodiles do not crawl forward with their bodies on the ground, but stagger, stretch their legs, float their bodies, and drag their tails to the ground.In fact, this description is an illusion of crocodiles.In fact, crocodiles are extremely sensitive in hearing and vision, and their body movements are also very flexible.Crocodile is a clever animal.For example, crocodiles have a strange way of hunting. When they swim in the water, they suddenly find a small animal. They are not eager to catch it immediately. Instead, they hide their bodies at the bottom of the water, and then swim quietly in the direction of the small animal. They first stare at each other motionlessly, then suddenly jump up to catch the small animal, and finally take it to the river with their mouths, drowning it,Have another hearty meal.According to anatomical analysis, crocodiles like to eat wild ducks, rabbits, frogs, mice, fish, snails and other animals.[1]
Nile Crocodile
Nile crocodiles have the habit of living in symbiosis with thousands of birds.This bird often perches on the Nile sandbar.It is good friends with crocodiles, often looking for worms to eat on crocodiles, and sometimes it can go into the mouth of crocodiles to peck and eat leeches parasitic in the mouth of crocodiles.Interestingly, sometimes the mouth of the crocodile closes accidentally, and the little Qianniao is locked in the mouth of the crocodile, but the crocodile does not swallow the bird. The little Qianniao will gently hit its upper and lower jaw, and the crocodile will immediately open its mouth to let the bird fly out.Qianniao is a kind of bird with keen sense. As long as it hears a little movement, it will shout and start up.Therefore, when the crocodile sleeps, the little thousand birds sometimes give it a "stand guard". Once there is a "situation", the thousand birds immediately make a noise, which wakes up the sleeping crocodile, so the crocodile can immediately sink into the water and avoid a disaster.[1]
Distribution range
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Crocodiles are mostly distributed in tropical areas of Africa, Asia, North and South America and Australia,Only Chinese alligators and American alligators live in temperate regions.[13-14]
Reproductive mode
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Before spawning, crocodiles will go to the shore to build their own "spawning room" with soft things such as leaves and hay, and use the sun's light and the heat of weeds to hatch their eggs,At the age of 12, she began to give birth. Each time she laid 10-90 eggs, it took 84-90 days for hatching.AlligatorFish live 65 years.[18-20]
History of Zoology
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Crocodile, as one of the oldest species on the earth so far, retains many characteristics of early dinosaurs and reptiles, also known as "living fossil".[21]
Crocodile is a reptile of Crocodile and Crocodile.[8]Crocodile has a long trunk;Muscular development;[9]The head is flat, the head skin is close to the skull, and the skull is firmly connected, unable to move;The teeth are conical and grow in the alveoli, with more than 25 teeth on each side;The tongue is short and flat, and cannot protrude;Eyes are small and slightly protruding;The tail is thick and slightly flat;[10]Short and thick limbs;The outer nostril is located on the back of the tip of the snout, with valves on it;[11]There are armor like scales.[12]
Crocodile It useslungFor breathing, the heart is divided into four chambers. There is a bone palate on the top wall of its mouth, which separates the nasal cavity from the oral cavity. Its teeth only grow in the alveoli of the upper and lower jaw. These are similar to mammals, which indicates that mammals are evolved from reptiles.The crocodile has two eyes on the top of its head. In addition to its eyelids, it also has a transparent blink film. This structure enables it to adapt to the water environment.Because the crocodile's nostril is located on the back of the upper end, there is a valve inside, so when it dives into the water, the valve automatically closes, which can prevent water from flowing into the nostril. In its pharynx, there is a thin and elastic membrane. When this membrane is closed, its mouth and respiratory tract will be separated. Therefore, even if it opens its mouth wide in the water, water will not enter the respiratory tract and lungs.Its long and thick tail is not only a "rudder" for swimming, but also a tool for hunting and a weapon for defending the enemy.[1]
The largest individual in crocodiles isBay crocodileThe average body length is 4 meters. The smallest individual is the Chinese alligator living in China, which is only about 1.25 meters long.
Subordinate classification
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There are 8 genera and 23 species of crocodiles.[9]
continent
name
Body length
Living area
Scientific name
Asia
Piscivorous alligator
3.5m
India
Gavial
Asia
Chinese alligator
1.5 to 2m
China
Chinese Crocodile
Asia
Estuarine alligator
4 to 6 meters
Southeast Asia and Northern Australia
Salt-water Crocodile
Africa
Nile crocodile
5.47m
Madagascar, Africa
Nile Crocodile
Oceania
Johnston's Crocodile
2.5 to 3m
The tropics of northern Australia
Johnston's Crocodile
America
Peteng alligator
3 to 3.4m
Mexico, Guatemala and Belize
Crocodylus moreletii
America
Alligator mississippiensis
3m
U.S.A
American Crocodile
America
American alligator
4m
North and South America
Alligator
America
black caiman
5m
South America
Black Caiman
America
Cuvier's dwarf caiman
1.5m
South America
Cuvier's Dwarf Caiman
[5]
There are 23 species, 8 genera, 3 families of crocodiles in the world, most of which are distributed in tropical and subtropical areas such as Africa, Central America and southern Asia. Only Chinese alligators in China and Mississippi alligators in North America are distributed in temperate zones.In China, there are mainly 6 crocodile breeds, namely Chinese alligator, Siamese crocodile (Thai crocodile), Nile crocodile, bay crocodile, Mississippi crocodile and Caiman crocodile.Among them, the Chinese alligator is unique to China, and the others are imported from abroad.[6]
Chinese alligator
Chinese alligator
Chinese alligatorAlligator sinensis, also known as tu ó, is a kind of crocodile unique to China and the most endangered crocodile in the world.Our country has listed it asNational first-class protected animals[26], killing is strictly prohibited.Chinese alligators are small. Adult alligators weigh about 36 kg, and their body length is generally 1.5 meters, rarely more than 2.1 meters.The Chinese alligator has short and thick limbs, five fingers on the forelimbs, and no web between the fingers;The hind legs have four toes, with web between the toes.The tail length is similar to the body length.The head is relatively large, flat and long snout.The eyes are all black, and have eyelids and membranes, which can be opened or closed.The back of the body is grayish brown, the front of the abdomen is gray, from the anus back to the grayish yellow, and the tail is flat.The newborn alligator is black with yellow stripes.[6]
Siamese crocodile
Siamese crocodile
Siamese crocodileCrocodylus siamensis, also known as Thai crocodile, Siamese freshwater crocodile and Singapore small crocodile, is mainly distributed in Southeast Asia, such as Borneo, Indonesia, Malaysia, Thailand and Vietnam.Siam crocodile leather has a high reputation in the world.Siamese crocodile is a medium-sized crocodile. When the young crocodile hatches, it is about 25 cm long. The adult crocodile can reach a maximum length of 4 meters, and the common crocodile is 3 meters long.The snout of Siamese alligator is medium in length and slightly concave.There is a pair of short sharp ridges in the front of the two orbits, and there is an obvious orbit between the two orbits on the forehead. The squama bone protrudes into a high ridge.It inhabits in tropical and subtropical swamps, slow flowing rivers and lakes and other fresh water areas, as well as salt and fresh water areas.They feed on fish, amphibians, reptiles and small mammals.They reach sexual maturity at the age of 10.It breeds in April to May every year. The female can lay 20-50 eggs at a time, and the incubation period is about 80 days.[6]
Nile crocodile
Nile crocodile
Nile crocodileCrocodylus niloticus is a large crocodile. The adult crocodile is 2-5.5 meters long and weighs up to 120 kg. It is the most studied crocodile among 23 crocodiles in the world.Nile crocodiles are olive green to brown, with black spots and reticular patterns.Nile crocodiles are very strong. Their tails are strong and helpful for swimming.The adult has dark horizontal stripes.The larva is dark yellow brown, with obvious transverse stripes on the body and tail.The female Nile crocodile can lay more than 50 eggs at a time, and hatch out of the shell three months later. The newborn Nile crocodile is about 30 cm long. The female crocodile gently holds them in her mouth and puts them into the water.Young alligators can grow to 60 cm at 1 year old and 1 m at 2 years old.[6]
Alligator mississippiensis
Alligator mississippiensis
Alligator mississippiensis Alligator mississippiensis, also known as River Alligator and Alligator americana, is only produced in the southeast of the United States and the Mississippi River Basin, and hence its name.Mississippi alligator is a large alligator with a body length of 4.9-6.1 meters, but few of the existing individuals grow to this size.It mainly inhabits marsh areas, and is also distributed in streams, rivers and lakes, and even in waters with flavor.The alligator can communicate with its peers through sound and vision.Mississippi crocodiles are listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora.[6]
Caiman
Caiman
CaimanCaiman crocodile refers to several alligators in South and Central America. They are related to alligators and belong to the family Alligator.The animals of this genus of caimans have a transverse bone ridge at the front of their eyes, which is very similar to the spectacle frames worn by people. Therefore, their English names are called "opticians".The maximum body length of ordinary caimans can reach 250 cm, the common adult can reach 150~200 cm, and the newly hatched caimans can reach 20~25 cm.The snout is slightly longer, the tip is slightly higher, and the snout length is slightly larger than the width of the snout base.The back is olive green. There are numerous dark spots on the head, body and tail. There are dark brown or black horizontal stripes on the back and tail. The belly is pure beige or light yellow.There are light colored spots on both sides of the jaw of newly hatched alligators, which disappear when the body length is about 35cm.The caiman mainly rests in the swift and rocky river.[6]
Bay crocodile
Bay crocodile
Bay crocodile(Crocodylus porosus), also known as cannibal crocodile, estuarine crocodile, saltwater crocodile and Malay crocodile, is the largest of 23 crocodile species and the largest reptile in the world.It is native to Thailand, Malaysia and other Southeast Asian regions. It is also found in India, and is mainly distributed from the coast of Southeast Asia to northern Australia and Papua New Guinea.It is also called "naked necked crocodile" because it is a crocodile without large scales on the nape of its neck.The adult length of the bay crocodile can reach 3~7 meters, up to 9 meters, and the weight is 600~1400 kg.The mating season lasts for several hours between May and June each year, while fertilization lasts only 1 to 2 minutes.The bay crocodile has a sense of territory, has a physiological structure that adapts to high salinity water quality, has a greater tolerance to seawater than ordinary crocodiles, and is suitable for living in different wetlands, such as estuaries, mangroves, swamps and other coastal and tidal zones.[6]
Among 23 crocodile species, 13 are included in the Red List of Endangered Species of the World Conservation Union.[24]
Siamese alligator is now on the verge of extinction.[24]
Chinese alligator is a special crocodile in China, and has been listed as a first-class protected animal in China.[25][26]
Endangered causes
Due to people's indiscriminate hunting and killing, the number of crocodiles is decreasing. Countries producing crocodiles have formulated laws to protect them.The Chinese alligator only lives in China and has become a rare wild animal in the world. In 1973, the International Conference on the Protection of Wildlife listed it as endangered species and prohibited species, and the Chinese alligator has been listed as a first-class protected animal in China.[2-3]
Related culture
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Large crocodiles pose a certain threat to human beings and will launch attacks suddenly before human beings respond.There is a western proverb "crocodile tears", which means false compassion. It means that crocodiles will slowly shed water like liquid from their eyes when swallowing larger animals, and it seems that crocodiles are shedding tears of sympathy.[22-23]
