Tadpoles are usually born in late spring and early summer. Frogs lay eggs from March to July every year, and the temperature in the north is low, so they lay eggs late. The climate in the south is warm, and most of them start spawning in March, and April is the peak of spawning. The newly hatched tadpoles are spindle-shaped and have no limbs. They have a long tail in the mouth and inner gills, and one side of the tail is flat, which is adsorbed on aquatic plants and nourished by the remaining yolk in the body, so they mainly live in groups.

In ancient times, tadpoles wrote "Kodou", which is the larva of frogs and toads, also called toad balls. The newly hatched tadpoles are spindle-shaped, with no limbs, mouth and inner gills, long tail, flat side and branched outer gills on both sides of the head, which are adsorbed on aquatic plants and fed by the remaining yolk in the body. Mainly in groups. When tadpoles mature, they begin to lose their shape, gradually grow limbs, and then (for frogs and toads) gradually degenerate their tails through apoptosis (controlling cell death).