How to Raise a Tadpole
Amphibian comes from the Greek, amphibios, which means to lead a double life. This group of animals includes frogs, toads, salamanders, newts and caecilians, which are legless, wormlike amphibians. Amphibians were the first four-limbed animals on land, forming a transition between the fish and the reptiles. Most begin their lives in the water. If you want to witness the dramatic metamorphosis of a water creature to a land creature, you won't do better than to raise tadpoles. It's easy, fun and fascinating.
Female frogs release their eggs by the thousands in early spring in freshwater pools and ponds where the males fertilize them. The eggs attach to plants in the water and within a couple of weeks the eggs hatch into tadpoles. This is the time to collect your young frogs. A net and a bucket are all you'll need. Fill the bucket with pond water and then net a few tadpoles. It's not as easy as it seems, but it is fun, if a little wet - so either wear boots or take off your shoes and socks.
Unless you're planning to raise your tadpoles in an outdoor pond, don't take too many. Tadpoles are voracious eaters (metamorphosis demands a good appetite), which means they release a great deal of waste and ammonia. This can quickly turn the tank poisonous.
Setting Up the Tank
Bring them back to a tank that you've prepared beforehand. Two tadpoles per gallon of water will prevent overcrowding. An aquarium or a large plastic washtub will do. The water doesn't have to be deep - just a few inches - but the bigger the surface area the better for allowing exchange of air and replenishment of oxygen. Make sure the container hasn't been washed with soap or cleansers. Fill it with clean, de-chlorinated water. Chlorine will kill your tadpoles.
Aquarium shops sell de-chlorinating liquid. Try to make sure the temperature of the tank is close to the temperature of the pond water. Because they're born in cold ponds and in spring when temperatures can vary, tadpoles are very hardy. But there's no reason to add more stress than you have to.
Depending upon the species of frog you've got, the transition from tadpole to adult frog can take from 2 months to more than a year. Gray treefrogs and American toads can metamorphose in several weeks while green frogs and bullfrogs can take a year or more. During this time feed them a couple of teaspoons of chopped boiled lettuce or spinach leaves twice a day along with a bit of crushed hard-boiled egg a couple of times a week.
How They Grow
What will you see? The tadpoles will begin to grow back legs, then front legs. Their tail will shrink and gradually disappear as the tadpoles use up the nutrients stored in them. Their heads become more and more frog-like and their jaws extend into the familiar frog shape.
Inside, the tadpoles, which had been breathing through gills as fish do, grow lungs so they can breathe air. Provide a rock that sticks out above the water in preparation for the day the froglets decide to come out on land. When they do, they'll begin eating insects, having gone from being vegetarians to meat eaters.
Is it a conservation concern to take tadpoles from the wild? According to Frank Indiviglio, a herpetologist with the Staten Island Zoo, taking the tadpoles of common species such as bullfrogs, green frogs, American and Fowler's toads are not much of a concern. First of all, many more tadpoles are born than will survive in the wild and second of all, since crowding your tank will kill your tadpoles, you are only taking a few. Ideally, once the frogs are grown, you will take them back to the pond from which you took the tadpoles in the first place. Check first with the conservation office of your state or county before netting your tadpoles to find out which species are too rare for you to collect. You can also get tadpoles at places that sell pond supplies, or from breeders. Releasing young frogs is usually no problem. Older frogs that have been kept as pets, however, can carry diseases into the wild.