Metamorphosis is a developmental process in which an organism matures a larval stage and gradually changes into an adult. The larval stage is markedly different from the adult stage. The larval stage undergoes several physical, chemical, physiological and behavioural changes. It is controlled by hormones and environmental factors. For example, metamorphosis of tadpole larva into an adult frog, where gills are replaced by lungs, tail is replaced by hind limbs, aquatic habit to terrestrial habit etc.