The greatest variety of tadpoles live in the tropics. Most tadpoles hatch from a jellylike mass of eggs laid in the water. A tadpole has a large, rounded head and a long, flat tail. It uses the tail to propel itself through the water. Tadpoles breathe by means of gills.
Most tadpoles eat algae and plant material.
A tadpole has no legs when it hatches, but it begins to grow hind legs during the first stages of metamorphosis. Gradually, its head flattens and the tail becomes shorter. The digestive system changes, enabling the tadpole to eat insects and other animals. During the final stages of metamorphosis, the tadpole's front legs appear. The gills disappear as lungs develop, forcing the tadpole to gulp air at the water's surface.