tadpole
The majority of amphibian species go through a larval stage that is very different from the adult form, as you can see from the frog in Figure below . The early larval, or tadpole , stage resembles a fish. It lacks legs and has a long tail, which it uses to swim. The tadpole also has gills to absorb oxygen from water. As the larva undergoes metamorphosis , it grows legs, loses its tail, and develops lungs. These changes prepare it for life on land as an adult frog.