A tadpole is basically a baby frog — it's the larval form of this aquatic animal. Tadpoles are tiny round creatures with long tails and gills for breathing underwater.
One of many amazing things about frogs and toads is the transformation they go through during their life cycle. Tadpoles, also called pollywogs, look like tiny fish. During metamorphosis, their gills become lungs, they grow legs, and their tails are absorbed into their bodies. Adult frogs have little resemblance to the tadpoles they once were. Tadpole comes from roots meaning "toad" and "head."