The larval form of amphibians is a tadpole, which is characterized by gill slits, a lateral line, a two-chamber heart, and one circle of blood circulation. These signs indicate the kinship of amphibians and fish. In the process of metamorphosis, which occurs under the influence of the thyroid hormone, the tail dissolves, limbs appear, the lateral line disappears, the lungs and the second circle of blood circulation develop.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.