Reptiles appeared 300 million years ago and were the first completely terrestrial vertebrates.

There are about 6,000 species of reptiles in existence, mainly living in tropical and some temperate zones.

The respiratory organ of reptiles is lungs, and some also breathe through their skin, which is covered with scales.

They are cold-blooded animals and cannot control the temperature of their bodies. Therefore, reptiles cannot be found in cold areas. They have to hibernate in winter.

Reptiles are divided into three categories: turtles, crocodiles, and snakes and lizards.

1. Turtles and soft-shell turtles: There are about 330 species of these reptiles.

They are short and wide, with soft bodies hidden in thick, hard shells.

They have no teeth, but their jaws are very strong and can cut through food.

Turtles have well-developed senses of smell and touch, but weak hearing and vision.

Most turtles are gentle and non-aggressive.

When encountering enemies, they will retract their heads and feet and hide them in their shells.

Looking at that stone-like hard shell, enemies often have nothing to do with it.

It is by virtue of this special ability that turtles have lived on the earth for 200 million years, and will continue to live peacefully and contentedly.

Turtles have a long lifespan, usually around 70 years, and most tortoises can live to be around 100 years old.

The reproductive mode of turtles is oviparous. They lay eggs very secretively. During the annual breeding season, female turtles quietly crawl to the beach under the cover of night and choose a place with sufficient sunshine and moderate temperature as a place to lay eggs.

Before laying eggs, the turtle will urinate on the sand to make the soil softer, and then dig a hole with its hind feet. When the hole is dug to a depth of more than 10 centimeters, the turtle will start to lay eggs in the hole. The eggs and

It is about the size of a table tennis ball, with a hard calcium shell on the outside.

This shell is a protective layer for the eggs, but it is an obstacle for the hatchlings that are about to rise. Fortunately, there is a hard protrusion between the mouth and nose of the hatchlings. With this "shell breaker"

, the hatchling struggled to drill, grind, and struggle, and finally drilled a small hole. It tried its best to break the eggshell with its head, and then the hatchling began to breathe for the first time.

As the hatchling hatches, its critical night of survival comes.

Young turtles are a delicacy for seabirds, tuatara, dogs, snakes, and more.

Young turtles are often eaten on their way to the sea, rivers, or ponds. Out of 100 hatchlings, only a few survive.

Turtles are the largest turtles.

Their nail length is generally around 100 centimeters.

Except for laying eggs or basking in the sun, sea turtles have always lived in the sea. Their feet have changed into flippers, which allow sea turtles to swim freely in the water.

Turtles have three feeding habits.

Tortoises are mostly herbivorous, feeding on straw and plant leaves.

Turtles are mostly carnivorous, preying on molluscs, shrimps and crabs.

Most freshwater turtles are omnivorous, eating aquatic plants and other vegetarian food, as well as river shrimp, frogs and fish.

There are approximately 32 species of turtles known today.

They live in fresh water.

The turtle often dives into the sand and mud at the bottom of the water, so its carapace becomes flat and flat.

The webbing between the toes of the turtle is very developed, so it can move quickly in the water and swim very fast.

The turtle is a natural diver. Its neck and nose are very long, which allows it to lie on the bottom of the water and breathe with its nose above the water.

2. Crocodile Crocodile is the largest and most dangerous reptile in existence, and it is also the most advanced category of reptiles.

There are 22 species of crocodiles, living in tropical areas around the world.

The largest crocodile is the Indo-Pacific crocodile, also known as the saltwater crocodile, which is 7 meters long and weighs about 300 kilograms. Traces of them can still be seen in the ocean 1,000 kilometers offshore.

Although they live in different habitats, have different sizes, and have different habits, they all have a ferocious appearance.

The crocodile's body is west long and covered with scales. Its teeth are like rows of small daggers in its mouth; its tail plays the role of rudder and oar, and controls the direction.

Crocodiles are carnivores and feed on insects, frogs, snails, fish, turtles, birds and large mammals.

Crocodiles are very cunning when hunting. They always hide their bodies in the water, leaving only their eyes, ears and nose protruding above the water. From a distance, they look like a piece of dead wood floating on the water.

When prey is found on the shore, this piece of "dead wood" will move to the shore unnoticed, and then pounce on the prey with lightning speed, bite it and drag it into the water. After several struggles,

, the prey becomes the crocodile’s delicacy.

A crocodile will have hundreds of teeth throughout its life—but they don't all grow at the same time.

Crocodiles often break or lose teeth while hunting, so they grow new ones as replacements.

"Crocodile tears" is synonymous with hypocrisy. In fact, crocodile tears have nothing to do with the crocodile's emotions. They are the way it excretes excess salt in its body.

Crocodiles don't sweat, and their kidneys have degenerated. They have specialized excretory glands in their bodies to excrete salt, and their excretion ducts are just around the eyes.

Crocodile tears are actually a salt solution.

3. Lizards When it comes to lizards, many people feel strange and think that they can only be seen in tropical jungles.

You would be surprised if someone told you that lizards live in almost every home around the world.

This is indeed true. Geckos are a kind of lizard. Many people have geckos in their homes. They help people get rid of pests in their homes.

Lizards are a prosperous group of reptiles, with a very diverse range of 3,000 species.