Frog-egg collecting is a fine thing to do in early spring, when you want to splash around in muddy pools.
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| Leopard frog eggs, tadpole, and adult. |
Such an expedition should be made in late March or early April. Take along some jars (for the eggs and extra pond water) and extra socks and shoes, or, better yet, rubber boots. Boots serve as protection from broken glass and rusty iron.
Usually the eggs of the common leopard frog will be found in shallow, sluggish waters. They are embedded in a semi-clear jelly-like mass about five inches in diameter and two and one-half inches thick. Such a mass may contain as many as 5,000 eggs. Each egg is about one-sixteenth of an inch in diameter and black at one pole, white at the other. So many dark eggs close together make the whole mass appear dark.
If you already know the leopard frog, you're probably wondering how a three or four inch animal manages to lay an egg mass larger than herself. Well, she doesn't! Each egg is surrounded by a jelly-like substance that quickly swells in water.
The development of the frog is one of the few instances in which anyone (with the use of a hand lens) may observe the growth of a complicated vertebrate animal from the very beginning‚ the one-celled egg stage. Zoology text books will show how the eggs look when they start to grow by dividing first into two cells, then into four, and, finally, into the millions of cells that make a frog.
A little black animal scarcely three-eighths of an inch long will hatch from the capsule-like egg about ten days after it has been laid. This tiny bit of life will at first stick to the jelly- like mass from which it wriggled; then it may swim around blindly until it touches something else that will support it.
About two weeks after the tadpole has hatched, it begins to feed by nibbling at grasses and scraping off tiny particles of food from objects in the water. Minute comb-like structures surrounding the horny beak aid in securing food.
Tadpoles in aquaria will eat small pond plants, pieces of lettuce, and tiny bits of hard-boiled egg. In feeding tadpoles give them only one-tenth of the amount you feel they should have - it will probably be too much; uneaten food only decays and produces bad odors.
Tadpoles get their oxygen from the water as fishes do; frogs breathe air as you do. The period during which the tadpole develops into a true frog includes some wonderful changes. You can see such changes as the slow growth of the hind legs (the front legs grow at the same time but are concealed), the loss of the tadpole mouth, and the appearance of an entirely different one. There are other changes that you cannot see, such as the shortening of the intestine and the switch from gills to lungs. While these changes are taking place, your pets will want little or no food.
If you are fortunate enough to bring tadpoles through these difficult transitional stages, you will need something at the surface (floating or jutting out) for your young frogs. You will also need screening to keep your pets in their container.
Adult frogs prefer live food that moves (insects, meal worms, etc.). You can gather insects by rapidly waving a butterfly net through high grass or by shaking bushes over an umbrella held upside down. Some frogs will eat bits of chopped meat waved about on the end of a stick.
Good luck with your collecting expedition, and remember that only the most careful and fortunate foster parents manage to rear baby frogs! Whipple
Review vocabulary from freedictionary.com:
- aquaria - A place for the public exhibition of live aquatic animals and plants.
- diameter - A straight line segment passing through the center of a figure, especially of a circle or sphere, and terminating at the periphery.
- Zoology - The branch of biology that deals with animals and animal life.
- Vertebrate - Having a backbone or spinal column.
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