Frogs are amphibians. They can jump around on the ground and swim around in crystal clear rivers. Frog was born as a small black tadpole, slowly, slowly growing its calf, and finally, it became a frog. Frog has two big eyes on its head, which looks scared. He is the "patron saint" of crops.

The fertilized egg of the frog, the frog larva just hatched is called tadpole. The newly hatched tadpoles have a spindle-shaped body, no limbs, mouths and internal gills, a long tail with a flat side, and branched external gills on both sides of the head, which are adsorbed on aquatic plants and fed by the remaining yolk in the body. Mainly live in groups. When tadpoles mature, they begin to lose their shape, gradually grow limbs and become small frogs. There are obvious differences between tadpoles and frogs.

Appearance: tadpoles have tails and no limbs; Frogs have no tail and four limbs.

Breathing: tadpoles breathe through gills; Frogs breathe with their lungs and skin.

Living environment: tadpoles are completely aquatic; Frogs are amphibious.

Little tadpoles are like this.

And here's the little frog.

The bigger frog is like this.

Frog is an amphibian belonging to Chordata, Amphibia, Anura and Ranidae. Its adult has no tail. Its eggs are laid in water, fertilized in vitro, hatched into tadpoles, and breathed through gills. After mutation, adults mainly breathe through lungs and skin.

Most frogs reproduce by in vitro fertilization, and fertilized eggs hatch outside the mother's body into tadpoles. Only 10 to 12 species of frogs in the world have evolved to fertilize in vivo, and some of them will excrete fertilized eggs and hatch into tadpoles. But in zoology, frog refers specifically to the black-spotted lateral fold frog. Frogs have always been regarded as oviparous animals, but scientists have found that a frog living in the rainforest of Sulawesi, Indonesia can give birth to tadpoles. This frog is the only frog among more than 6,000 kinds of frogs in the world that can "drop tadpoles". ? [ 1]?

Frogs are slim and good at swimming. The neck is not obvious and there are no ribs. The ulna and radius of the forelimb healed, and the tibia and fibula of the hind limb healed, so the claw could not rotate flexibly, but the limbs were muscular. The most primitive frogs began to evolve in the early Triassic. The earliest frog with jumping action appeared in Jurassic. Because frogs feed on insects and other invertebrates, they must live by the water. There are about 130 species of frogs in China, and almost all of them are experts in killing pests in forests and farmland.