Metamorphosis is the process of transformation between immature and mature forms in insects and amphibians. It involves two or more distinct life stages. In amphibians, metamorphosis allows for an aquatic larval stage and terrestrial adult stage. It involves growth of new structures like limbs and eyes, cell death of larval structures like tails and gills, and remodeling of tissues and organs. Hormonal control of metamorphosis is regulated by thyroid hormones which activate tissue-specific gene programs in a threshold dependent manner to drive the morphological changes between life stages.