Gateway to the Classics: Handbook of Nature Study: Frogs and Toads by Anna Botsford Comstock
 
Handbook of Nature Study: Frogs and Toads by  Anna Botsford Comstock

The Common Toad

Teacher's Story

"The toad hopped by us with jolting springs."

—Akers.

dropcap image HOEVER has not had a pet toad has missed a most entertaining experience. Toad actions are surprisingly interesting; one of my safeguards against the blues is the memory of the thoughtful way one of my pet toads rubbed and patted its stomach with its little hands after it had swallowed a June-bug. Toads do not make warts upon attacking hands, neither do they rain down nor are they found in the bed-rock of quarries; but they do have a most interesting history of their own, which is not at all legendary, and which is very like a life with two incarnations.

The mother toad lays her eggs in May and June in ponds, or in the still pools, along streams; the eggs are laid in long strings of jellylike substance, and are dropped upon the pond bottom or attached to water weeds; when first deposited, the jelly is transparent and the little black eggs can be plainly seen; but after a day or two, bits of dirt accumulate upon the jelly, obscuring the eggs. At first the eggs are spherical, like tiny black pills, but as they begin to develop, they elongate and finally the tadpoles may be seen wriggling in the jelly mass, which affords them efficient protection. After four or five days, the tadpoles usually work their way out and swim away; at this stage, the only way to detect the head, is by the direction of the tadpole's progress, since it naturally goes head first. However, the head soon becomes decidedly larger, although at first it is not provided with a mouth; it has instead, a V-shaped elevation where the mouth should be, which forms a sucker secreting a sticky substance by means of which the tadpole attaches itself to water weeds, resting head up. When two or three days old, we can detect little tassels on either side of the throat, which are the gills by which the little creature breathes; the blood passes through these gills, and is purified by coming in contact with the air which is mixed in the water. About ten days later, these gills disappear beneath a membrane which grows down over them; but they are still used for breathing, simply having changed position from the outside to the inside of the throat. The water enters the nostrils to the mouth, passes through an opening in the throat and flows over the gills and out through a little opening at the left side of the body; this opening or breathing-pore, can be easily seen in the larger tadpoles; and when the left arm develops, it is pushed out through this convenient orifice.

When about ten days old, the tadpole has developed a small, round mouth which is constantly in search of something to eat, and at the same time constantly opening and shutting to take in air for the gills; the mouth is provided with horny jaws for biting off pieces of plants. As the tadpole develops, its mouth gets larger and wider and extends back beneath the eyes, with a truly toadlike expansiveness.

At first, the tadpole's eyes are even with the surface of the head and can scarcely be seen, but later they become more prominent and bulge like the eyes of the adult toad.

The tail of the tadpole is long and flat, surrounded by a fin, thus making an organ for swimming. It strikes the water, first this side and then that, making most graceful curves, which seem to originate near the body and multiply toward the tip of the tail. This movement propels the tadpole forward, or in any direction. The tail is very thin when seen from above; and it is amusing to look at a tadpole from above, and then at the side; it is like squaring a circle.


[Illustration]

Toad's eggs.

Photo by Verne Morton.

There is a superstition that tadpoles eat their tails; and in a sense this is true, because the material that is in the tail is absorbed into the growing body; but the last thing a right-minded tadpole would do, would be to bite off its own tail. However, if some other tadpole should bite off the tail or a growing leg, these organs conveniently grow anew.

When the tadpole is a month or two old, depending upon the species, its hind legs begin to show; they first appear as mere buds which finally push out completely. The feet are long and provided with five toes, of which the fourth is the longest; the toes are webbed so that they may be used to help in swimming. Two weeks later the arms begin to appear, the left one pushing out through the breathing-pore. The "hands" have four fingers and are not webbed; they are used in the water for balancing; while the hind legs are used for pushing, as the tail becomes smaller.

As the tadpole grows older, not only does its tail become shorter but its actions change. It now comes often to the surface of the water in order to get more air for its gills, although it lacks the frog tadpole's nice adjustment of the growing lungs and the disappearing gills. At last some fine rainy day, the little creature feels that it is finally fitted to live the life of a land animal. It may not be a half inch in length, with big head, attenuated body and stumpy tail, but it swims to the shore, lifts itself on its front legs, which are scarcely larger than pins, and walks off, toeing in, with a very grown up air, and at this moment, the tadpole attains toadship. Numbers of them come out of the water together, hopping hither and thither with all of the eagerness and vim of untried youth. It is when issuing thus in hordes from the water and seen by the ignorant, that they gain the reputation of being rained down, when they really were rained up. It is quite impossible for a beginner to detect the difference between the toad and the frog tadpole; usually those of the toads are black, while those of the frogs are otherwise colored, though this is not an invariable distinction. The best way to distinguish the two is to get the eggs and develop the two families separately.

The general color of the common American toad is extremely variable. It may be yellowish-brown, with spots of lighter color, and with reddish or yellow warts. There are likely to be four irregular spots of dark color along each side of the middle of the back, and the under parts are light colored, often somewhat spotted. The throat of the male toad is black and he is not so bright in color as is the female. The warts upon the back are glands, which secrete a substance disagreeable for the animal seeking toad dinners. This is especially true of the glands in the elongated swelling or wart, above and just back of the ear, which is called the parotid gland; these give forth a milky, poisonous substance when the toad is seized by an enemy, although the snakes do not seem to mind it. Some people have an idea that the toad is slimy, but this is not true; the skin is perfectly dry. The toad feels cold to the hand because it is a cold-blooded animal, which means an animal with blood the temperature of the surrounding atmosphere; while the blood of the warm-blooded animal, has a temperature of its own, which it maintains whether the surrounding air is cold or hot.

The toad's face is well worth study; its eyes are elevated and very pretty, the pupil being oval and the surrounding iris shining like gold. The toad winks in a wholesale fashion, the eyes being pulled down into the head; the eyes are provided with nictitating lids, which rise from below, and are similar to those found in birds. When a toad is sleeping, its eyes do not bulge but are drawn in, so as to lie even with the surface of the head. The two tiny nostrils are black and are easily seen; the ear is a flat, oval spot behind the eye and a little lower down; in the common species it is not quite so large as the eye; this is really the ear-drum, since there is no external ear like ours. The toad's mouth is wide and its jaws are horny; it does not need teeth since it swallows its prey whole.


[Illustration]

After a hard winter.

Photo by Cyrus Crosby.

The toad is a jumper, as may be seen from its long, strong hind legs, the feet of which are also long and strong and armed with five toes that are somewhat webbed. The "arms" are shorter and there are four "fingers" to each "hand;" when the toad is resting, its front feet toe-in, in a comical fashion. If a toad is removed from an earth or moss garden, and put into a white wash-bowl, in a few hours it will change to a lighter hue, and vice versa. This is part of its protective color, making it inconspicuous to the eyes of its enemy. It prefers to live in cool, damp places, beneath sidewalks or piazzas, etc., and its warty upper surface resembles the surrounding earth. If it is disturbed, it will seek to escape by long leaps and acts frightened; but if very much frightened, it flattens out on the ground, and looks so nearly like a clod of earth that it may escape even the keen eyes of its pursuer. When seized by the enemy, it will sometimes "play possum," acting as if it were dead; but when actually in the mouth of the foe, it emits terrified and heart-rending cries.

The toad's tongue is attached to the lower jaw, at the front edge of the mouth; it can thus be thrust far out, and since it secretes a sticky substance over its surface, any insects which it touches adhere, and are drawn back into the mouth and swallowed. It takes a quick eye to see this tongue fly out and make its catch. The tadpole feeds mostly upon vegetable matter, but the toad lives entirely upon small animals, usually insects; it is not particular as to what kind of insects; but because of the situations which it haunts, it usually feeds upon those which are injurious to grass and plants. Indeed, the toad is really the friend of the gardener and farmer, and has been most ungratefully treated by those whom it has befriended. If you doubt that a toad is an animal of judgment, watch it when it finds an earthworm and set your doubts at rest! It will walk around the squirming worm, until it can seize it by the head, apparently knowing well that the horny hooks extending backward from the segments of the worm, are likely to rasp the throat if swallowed the wrong way. If the worm prove a too large mouthful, the toad promptly uses its hands in an amusing fashion to stuff the wriggling morsel down its throat. When swallowing a large mouthful, it closes its eyes; but whether this aids the process, or is merely an expression of bliss, we have not determined. The toad never drinks by taking in water through the mouth, but absorbs it through the skin; when it wishes to drink, it stretches itself out in shallow water and thus satisfies its thirst; it will waste away and die in a short time, if kept in a dry atmosphere.

The toad burrows in the earth by a method of its own, hard to describe. It kicks backward with its strong hind legs, and in some mysterious way, the earth soon covers all excepting its head; then, if an enemy comes along, back goes the head, the earth caves in around it, and where is your toad! It remains in its burrow or hiding place usually during the day, and comes out at night to feed. This habit is an advantage, because snakes are then safely at home and, too, there are many more insects to be found at night. The sagacious toads have discovered that the vicinity of street lights is swarming with insects, and there they gather in numbers. In winter they burrow deeply in the ground and go to sleep, remaining dormant until the warmth of spring awakens them; then, they come out, and the mother toads seek their native ponds there to lay eggs for the coming generation. They are excellent swimmers; when swimming rapidly, the front legs are laid backward along the sides of the body, so as to offer no resistance to the water; but when moving slowly, the front legs are used for balancing and for keeping afloat.

The song of the toad is a pleasant, crooning sound, a sort of gutteral trill; it is made when the throat is puffed out almost globular, thus forming a vocal sac; the sound is made by the air drawn in at the nostrils and passed back and forth from the lungs to the mouth over the vocal chords, the puffed-out throat acting as a resonator.

The toad has no ribs by which to inflate the chest, and thus draw air into the lungs, as we do when we breathe; it is obliged to swallow the air instead and thus force it into the lungs. This movement is shown in the constant pulsation, in and out, of the membrane of the throat. As the toad grows, it sheds its horny skin, which it swallows; as this process is usually done strictly in private, the ordinary observer sees it but seldom. One of the toad's nice common qualities is its enjoyment in having its back scratched gently.

The toad has many enemies; chief among these is the snake and in only a lesser degree, crows and also birds of prey.


Reference—The Frog Book, Dickerson; Familiar Life in Field and Forest, Mathews; The Usefulness of the American Toad, U. S. Dept. Agr., Farmers Bulletin, No. 196.


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 washbowl.


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.


[Illustration]


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 jelly-like 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?


[Illustration]

Toad development in a single season (1903).

1-18, Changes and growth from April to November;
9-14, Different sizes, July 30, 1903;
1-13 Development in 25 to 60 days;
15-18 Different sizes, October 21, 1903;
10, 11. The same tadpole, 11 is 47 hours older than 10;
12, 13, The same tadpole, 13 is 47 hours older than 12

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?


Lesson XLV

The Toad

Leading thought—The toad is colored so that it resembles the soil and thus escapes the observation of its enemies. It lives in damp places and eats insects, usually hunting them at night. It has powerful hind legs and is a vigorous jumper.


Method—Make a moss garden in a glass aquarium jar thus: Place some stones or gravel in the bottom of the jar and cover with moss. Cover the jar with a wire screen. The moss should be deluged with water at least once a day and the jar should be placed where the direct sunlight will not reach it. In this jar, place the toad for study.


Observations—

1. Describe the general color of the toad above and below. How does the toad's back look? Of what use are the warts on its back?

2. Where is the toad usually found? Does it feel warm or cold to the hand? Is it slimy or dry? The toad is a cold-blooded animal, what does this mean?

3. Describe the eyes and explain how their situation is of special advantage to the toad. Do you think it can see in front and behind and above all at the same time? Does the bulge of the eyes help in this? Note the shape and color of the pupil and iris. How does the toad wink?

4. Find and describe the nostrils. Find and describe the ear. Note the swelling above and just back of the ear. Do you know the use of this?

5. What is the shape of the toad's mouth? Has it any teeth? Is the toad's tongue attached to the front or the back part of the mouth? How is it used to catch insects?

6. Describe the "arms and hands." How many "fingers" on the "hand?" Which way do the fingers point when the toad is sitting down?

7. Describe the legs and feet. How many toes are there? What is the relative length of the toes and how are they connected? What is this web between the toes for? Why are the hind legs so much larger than the front legs?

8. Will a toad change color if placed upon different colored objects? How long does it take it to do this? Of what advantage is this to the toad?

9. Where does the toad live? When it is disturbed how does it act? How far can it jump? If very frightened does it flatten out and lie still? Why is this?

10. At what time does the toad come out to hunt insects? How does it catch the insect? Does it swallow an earthworm head or tail first? When swallowing an earthworm or large insect, how does it use its hands? How does it act when swallowing a large mouthful?

11. How does the toad drink? Where does it remain during the day? Describe how it burrows into the earth.

12. What happens to the toad in the winter? What does it do in the spring? Is it a good swimmer? How does it use its legs in swimming?

13. How does the toad look when croaking? What sort of a noise does it make?

14. Describe the action of the toad's throat when breathing. Did you ever see a toad shed its skin?

15. What are the toad's enemies? How does it act when caught by a snake? Does it make any noise? Is it swallowed head or tail first? What means has it of escaping or defending itself from its enemies?

16. How is the toad of great use to the farmer and gardener?


References—"The Life History of the Toad," by S. H. Gage, Cornell Nature-Study Volume; The Frog Book, Dickerson.


Supplementary reading—"K'dunk, the fat one," A Little Brother to the Bear, Long.


"In the early years we are not to teach nature as science, we are not to teach it primarily for method or for drill: we are to teach it for loving—and this is nature study. On these points I make no compromise."

—L. H. Bailey.

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