Tadpoles are the infant stage of frogs, so they have a slightly different relationship to frogs than human children have to human adults. Growth and development in tadpoles is dependent on the health of their thyroid and pituitary glands, which in turn are dependent on adequate nutrition. If there is IODINE present in the water in which the tadpoles live, theywill grow to be frogs. Iodine is an essential mineral for growth, and can be found in sea water, most soils, and iodized salt