[Comparative study of iodine and thyroid gland in biological processes: development and reproduction]

Iodine is an scarce metalloid, essential for life, more abundant in the aquatic ecosystem than in land. Marine species do not need to store and transform the inorganic iodine into organic iodine through the thyroid gland. Adaptation to terrestrial ecosystem has required phylogenetic processes, and animal species have used different strategies to solve the iodine captation problem according to their needs. Jellyfish lack of thyroid gland while lampery developed the thyroid gland during evolution in order to adapt to the terrestrial ecosystem. This review is a comparative phylogenetic study of thyroid gland development and iodine physiology, includes functional disorders, as well as iodine captation ability and requirements during growth and reproduction in different species.