A pollywog is another name for a tadpole, or the larval stage in the life cycle of an amphibian, namely frogs and toads. While most tadpoles are aquatic and spend most all their time in the water, a few are terrestrial.
Pollywogs breathe by means of outward or inward gills and feed mainly on plants and algae. As the young amphibians mature, they gradually grow arms and legs, outwardly absorbing their tail by apoptosis. Around the same time, pollywogs begin developing lungs and are commonly found near the surface of the water breathing air as they make the transition to adulthood.