What are the characteristics of frogs?

Frog, English name frog. It is an amphibian, mainly including toad and frog. They have no tails as adults, and their eggs are laid in water. After hatching, they become tadpoles and breathe through their gills. After metamorphosis, adults mainly breathe through the lungs, but most skin also has some breathing function. Frogs and toads are not much different, but there are two kinds in the same family. Generally speaking, toads live on land, so their skin is rough; Frogs are slim and good at swimming. The two bodies are similar, with inconspicuous necks and no ribs. The ulna and radius of the forelimb are healed, and the tibia and fibula of the hind limb are healed, and the claws cannot rotate flexibly, but the limbs are muscular. Frogs are called good friends of human beings because they feed on pests.

Anurak is the first step for creatures to land from the water, which is more advanced than other amphibians. Although most of them can survive without water, their reproduction is still inseparable from water, and eggs need to undergo metamorphosis in water to grow. So it is not as advanced as reptiles, and it is completely possible to live without water.

Interesting frog

Appearance characteristics

There are about 4,800 kinds of frogs, most of which live in water, and some live in trees in the humid environment of the rainforest. Although frogs are amphibians, they can't be completely out of water. They need to lay eggs in the water and go through the tadpole stage before they can reproduce. Of course, there are also tree frogs that can make their eggs pass the tadpole stage by accumulating residual puddles in tree holes or plant leaf roots. In 2003, a new species of "purple frog" was discovered in western India. It lives in underground caves all the year round and only comes out to give birth when the monsoon brings rain. In Liwan District, Guangdong, China, a kind of "fluctuating frog" was also found, but its shape was more like a toad. It is difficult to distinguish frogs from toads absolutely. Some families, such as Bufonidae, include both frogs and toads. However, the latest species "fluctuation frog" has not been classified.

According to the size of the frog, the smallest is only 50 mm, only as long as a person's thumb, and the largest is 300 mm (more than a foot long). The pupil is horizontal, the skin is smooth, the tip of the tongue is forked, and the tongue follows the front of the mouth, so you can suddenly turn it out to catch insects. There are three eyelids, one of which is transparent to protect the eyes in water, and the other two upper and lower eyelids are common. There are two sound sacs on both sides of the head, which can produce * * * and amplify sound. Smaller varieties have higher frequency of calls. Some frogs' skin secretes venom to prevent natural enemies. A tree frog secretion living in the Amazon rain forest was used by local Indians to make curare and seal their throats with blood.

distribution range

Frogs are distributed all over the world, except the Caribbean islands and the Pacific islands. However, due to climate change, environmental pollution and the invasion of alien species, the frog habitat is gradually shrinking, resulting in a rapid decline in the number of frogs around the world.

Living habits

Frogs basically prey at night, mainly insects, but large frogs can prey on fish, mice and even birds. Frog has the reputation of being a friend of mankind, because it can prey on a large number of field pests and is beneficial to human beings. It is not only the natural enemy of pests, but also the guardian of harvest. The familiar and pleasant sound of frogs is actually like beautiful music that nature can never play, and it is a quiet and harmonious field song. "There is a bumper harvest in Taoxiang, listening to frogs." Frogs always bring farmers the hope of sowing, and always drive the joy and joy of harvest!

history

The most primitive evolution of frogs began in the early Triassic. It is an amphibian. The earliest frog with jumping action appeared in Jurassic. With the continuous evolution of frogs, there are all kinds of scary and grotesque frogs. Frog skin can secrete venom, and its main purpose is to prevent natural enemies. The secretion of a tree frog living in the rainforest of the Amazon River basin is made into a poisonous arrow, and one arrow can be fatal.

Frog ancestors originally lived in water, but due to the change of living environment, some rivers and lakes became land, so frog ancestors had to develop from water to land with the change of environment. The change of living environment forces frog ancestors to make corresponding "adjustments" to their body organs to adapt to the change of environment. Some species that can adapt to land life survived. The moving organ has changed from a tail that swims in water to limbs that can move on land and in water, and the respiratory organ has changed from gills to lungs. Frog ancestors did not completely change from aquatic to terrestrial, so they laid eggs in the water later and tadpoles developed into adults. Maybe this is the legacy left by frog ancestors! From the development of frog larvae.

Insect trap

Frogs are good at catching insects. They prefer to eat small insects, so they have their own methods to catch them. A frog was lying in a small pit, kneeling on the ground with its hind legs curled up, its front legs supported, its face upturned with its mouth open and its belly bulging, waiting for its prey to arrive. A mosquito flew by, and the frog jumped up, turned his tongue and fell to the ground again. The mosquito disappeared, and it returned to its original appearance, waiting for the arrival of the next target.

singer

Frog is a clever singer. There is a bulging thing in its mouth, which is its sound sac. It can sing loudly at any time. Frog's vocal cords are located above hilar cartilage. On both sides of some male frogs' squabbles, there are external sound sacs that can expand and vibrate, and the sound sacs produce * * * sounds, which make the frogs' songs magnificent and loud. When you walk to the pond after the rain, you will hear the cries of male frogs echoing each other, one after another, forming a chorus. Scientists point out that frog chorus is a veritable chorus, which has certain rules, including lead singer, chorus, chorus and accompaniment, and is closely coordinated with each other. It is speculated that chorus is much better than solo because it contains more information. Chorus is loud and far away, which can attract more female frogs, so frogs often use chorus. It can be seen that frog is still a very scheming animal!

Master of physical education

Although the frog looks silly on the surface, it is smart! Its eyes are bulging, its head is triangular, its crawling action is slow, but its jumping ability is first-class. When you get a little closer, they will jump, and the distance of this jump can be 20 times its body length. And he is also a good swimmer, because we learned the breaststroke posture from others while swimming. Sometimes, animals are really the best teachers for human beings.

The Great Impostor

Look at it. It's stupid, but I didn't expect him to be a master in disguise. This frog has a white belly, a yellow-green head and back, and some dark brown stripes. Some have three white marks on their backs. Why are frogs green? It turns out that the frog's green clothes are a good disguise. When it is in the grass, it is almost the same color as grass to prevent itself from being discovered by the enemy.

Frog's head has two round and prominent eyes, a wide and big mouth and a long tongue. The back of the body is green with dark stripes and the abdomen is white. There are four legs under the body, the front leg is short, the back leg is long, and there is webbed toes. It is convenient for him to travel between land and water.