Lesson XLIV

The Tadpole Aquarium

Leading thought—The children should understand how to make the tadpoles comfortable and thus be able to rear them.

Materials—A tin or agate pan or a deep earthenware wash-bowl.

Things to be done—1. Go to some pond where tadpoles live.

2. Take some of the small stones on the bottom and at the sides of the pond lifting them very gently so as not to disturb what is growing on their surface. Place these stones on the bottom of the pan, building up one side higher than the other, so that the water will be more shallow on one side than on the other; a stone or two should project above the water.

3. Take some of the mud and leaves from the bottom of the pond, being careful not to disturb them and place upon the stones.

4. Take some of the plants found growing under water in the pond and plant them among the stones.

5. Carry the pan thus prepared back to the schoolhouse and place it where the sun will not shine directly upon it.

6. Bring a pail of water from the pond and pour it very gently in at one side of the pan, so as not to disarrange the plants; fill the pan nearly to the brim.

7. After the mud has settled and the water is perfectly clear, remove some of the tadpoles, which have hatched in the glass aquarium, and place in the “pond.” Not more than a dozen should be put in a pan of this size, since the amount of food and microscopic plants which are on the stones in the mud, will afford food for only a few tadpoles.

8. Every week add a little more mud from the bottom of the pond or another stone covered with slime, which is probably some plant growth. More water from the pond should be added to replace that evaporated.

9. Care should be taken that the tadpole aquarium be kept where the sun will not shine directly upon it for any length of time, because if the water gets too warm the tadpoles will die.

10. Remove the “skin” from one side of a tulip leaf, so as to expose the pulp of the leaf, and give to the tadpoles every day or two. Bits of hard-boiled egg should be given now and then.

Toads’ Eggs and Tadpoles

Leading thought—The toad’s eggs are laid in strings of jelly in ponds. The eggs hatch into tadpoles which are creatures of the water, breathing by gills, and swimming with a long fin. The tadpoles gradually change to toads, which are air-breathing creatures, fitted for life on dry land.

Method—The eggs of toads may be found in almost any pond about the first of May and may be scraped up from the bottom in a scoop-net. They should be placed in the aquarium where the children can watch the stages of development. Soon after they are hatched, a dozen or so should be selected and placed in the tadpole aquarium and the others put back into the stream. The children should observe the tadpoles every day, watching carefully all the changes of structure and habit which take place. If properly fed, the tadpoles will be ready to leave the water in July, as tiny toads.

Observations—1. Where were the toads’ eggs found and on what date? Were they attached to anything in the water or were they floating free? Are the eggs in long strings? Do you find any eggs laid in jellylike masses? If so, what are they? How can you tell the eggs of toads from those of frogs?

2. Is the jellylike substance in which the eggs are placed clear or discolored? What is the shape and the size of the eggs? A little later how do they look? Do the young tadpoles move about while they are still in the jelly mass?

3. Describe how the little tadpole works its way out from the jelly covering. Can you distinguish then which is head and which is tail? How does it act at first? Where and how does it rest?

4. Can you see with the aid of a lens the little fringes on each side of the neck? What are these? Do these fringes disappear a little later? Do they disappear on both sides of the neck at once? What becomes of them? How does the tadpole breathe? Can you see the little hole on the left side, through which the water used for breathing passes?

5. How does the tail look and how is it used? How long is it in proportion to the body? Describe the act of swimming.

6. Which pair of legs appears first? How do they look? When they get a little larger are they used as a help in swimming? Describe the hind legs and feet.

7. How long after the hind legs appear before the front legs or arms appear? What happens to the breathing-pore when the left arm is pushed through?

8. After both pairs of legs are developed what happens to the tail? What becomes of it?

9. When the tadpole is very young can you see its eyes? How do they look as it grows older? Do they ever bulge out like toads’ eyes?

10. As the tadpole gains its legs and loses its tail how does it change in its actions? How does it swim now? Does it come oftener to the surface? Why?

11. Describe the difference between the front and the hind legs and the front and the hind feet on the fully grown tadpole. If the tail or a leg is bitten off by some other creature will it grow again?