What is the process called when a tadpole develops into a frog?

The process called metamorphosis is when a tadpole develops into a frog. It is a dramatic biological transformation from an aquatic larva into an air-breathing young frog.

During metamorphosis, the tadpole first grows hind legs and then front legs. Its lungs develop as its gills disappear, allowing it to breathe air. The long tail is gradually absorbed, and the body reshapes for life on land or in shallow water.

The change is controlled largely by thyroid hormones, especially thyroxine. The tadpole’s digestive system also changes: its long, spiral gut, suited to a mostly plant-based diet, becomes shorter and better suited to the adult frog’s usually carnivorous diet.

A common mix-up is calling this simply “growth.” Growth means getting larger, while metamorphosis includes major changes in body structure and lifestyle. The word also applies more broadly to dramatic developmental changes in animals such as insects and salamanders.