The term for creatures that undergo metamorphosis is "metamorphic." This biological process involves a significant transformation in the animal's physical structure during its lifecycle, especially occurring in species such as amphibians, insects, and some fish. Common examples include the transformation of a caterpillar into a butterfly and a tadpole into a frog. Metamorphosis typically involves distinct stages: larva, pupa, and adult for insects. These changes often allow the creatures to adapt to different environments, reduce competition for resources, and improve survival rates by exploiting various ecological niches.