Tadpoles are the aquatic larvae of an amphibian, which means they are baby frogs, toads or salamanders that live in water. These tiny creatures, also called polliwogs, look like little fish with fat heads and bellies. They are usually black or brown. Tadpoles live in fresh-water ponds and slow-moving streams until they morph into adults and live on the land. Chances are that if you point out some tadpoles to your kids, they're going to want to know more about them. If they're not yet old enough to study tadpoles in school, you'll want to be up to speed on your tadpole facts to provide your kids with accurate information.
You can explain to your kids that many adult amphibians, such as frogs, toads and salamanders, lay their eggs in fresh water ponds and streams. You might also explain that some, including several species of frogs, lay large masses of eggs encased in jelly. However, some salamanders and frogs lay one egg at a time. Toads lay eggs in a long string that looks like a string of beads. If you go out looking for eggs, you might find them clinging to underwater plants or floating on the top of a pond, depending on the type of amphibian that laid them.
Life in the Pond as a Tadpole
You should also tell your kids that tiny tadpoles start their lives as black or brown dots in the center of an egg. As they begin to grow, you can see the eggs wiggle inside the jelly. The tadpole eats the jelly from the egg and eventually works his way out of the egg. When tadpoles hatch from the egg, they have a long tail and gills for breathing in water. Explain that tadpoles eat plants and algae for several weeks as they grow larger. As tadpoles grow bigger, they get tiny teeth and begin to eat small insects in the water.
Morphing Away -- Growing Legs and Losing the Tail
Let your kids know that tadpoles gradually change their appearances until they look like their parents. This process, called metamorphosis, might take a few weeks or several months, depending on the kind of amphibian the tadpole is. First the tadpole grows hind legs -- and then front legs pop out of his sides. If you look closely at a tadpole, you might see the bulges for his front legs before they appear. The heads of frog and toad tadpoles grow larger -- and the tails begin to disappear.
Goodbye Gills: Hello Lungs
Explain that at the same time the tadpole is busy growing legs, his gills begin to disappear and he develops lungs for breathing air. You might witness this occurring if you see what looks like a tiny frog or toad with a long tail coming to the surface of the water for air, or even climbing onto the land. When their tails disappear completely and their lungs are fully developed, the frog and toad tadpoles leave the pond to live on land. Note to your kids that salamander tadpoles don't lose their tails, but they do develop legs and lungs for life on land.
Starting Over Again
Finally, you want to tell your kids that when the tadpoles become adult frogs, toads and salamanders, they return to the water in the spring to mate and lay eggs. This starts the life cycle all over again.