TURTLE is at heart a misanthrope; its shell is in itself proof of its owner's distrust of this world. But we need not wonder at this misanthropy, if we think for a moment of the creatures that lived on this earth, at the time when turtles first appeared. Almost any of us would have been glad of a shell in which to retire, if we had been contemporaries of the smilodon and other monsters of earlier geologic times.
When the turtle feels safe and walks abroad for pleasure, his head projects far from the front end of his shell, and the legs, so wide, and soft that they look as if they had no bones in them, project out at the side, while the little, pointed tail brings up an undignified rear; but frighten him and at once head, legs and tail all disappear, and even if we turn him over, we see nothing but the tip of the nose, the claws of the feet and the tail turned deftly sidewise. When frightened, he hisses threateningly; the noise seems to be made while the mouth is shut, and the breath emitted through the nostrils.
The upper shell of the turtle is called the carapace and the lower shell, the plastron. There is much difference in the different species of turtles in the shape of the upper shell and the size and shape of the lower one. In most species the carapace is sub-globular but in some it is quite flat. The upper shell is grown fast to the backbone of the animal, and the lower shell to the breast bone. The markings and colors of the shell offer excellent subjects for drawing. The painted terrapin has a red-mottled border to the shell, very ornamental; the wood turtle has a shell made up of plates each of which is ornamented with concentric ridges; and the box-turtle has a front and rear trap-door, hinged to the plastron, which can be pulled up against the carapace when the turtle wishes to retire, thus covering it entirely.
The turtle's head is decidedly snakelike. Its color differs with different species. The wood turtle has a triangular, horny covering on the top of the head, in which the color and beautiful pattern of the shell are repeated; the underparts are brick-red with indistinct yellowish lines under the jaw. The eyes are black with a yellowish iris, which somehow gives them a look of intelligence. The turtle has no eyelids like our own, but has a nictitating membrane which comes up from below and completely covers the eye; if we seize the turtle by the head and attempt to touch its eyes, we can see the use of this eyelid. When the turtle winks, it seems to turn the eyeball down against the lower lid.
The sense of smell in turtles is not well developed, as may be guessed by the very small nostrils, which are mere pin-holes in the snout. The mouth is a more or less hooked beak, and is armed with cutting edges instead of teeth. The constant pulsation in the throat is caused by the turtle swallowing air for breathing.
The turtle's legs, although so large and soft, have bones within them, as the skeleton shows. The claws are long and strong; there are five claws on the front and four on the hind feet. Some species have a distinct web between the toes; in others, it is less marked, depending upon whether the species lives mostly in water or out of it. The color of the turtle's body varies with the species; the body is covered with coarse, rough skin made up of various-sized plates.
The enemies of turtles are the larger fishes and other turtles. Two turtles should never be kept in the same aquarium, since they eat each others' tails and legs with great relish. They feed upon insects, small fish, or almost anything soft-bodied which they can find in the water; they are especially fond of earthworms. The species which frequent the land, feed upon tender vegetation and also eat berries. In an aquarium, a turtle should be fed earthworms, chopped fresh beef, lettuce leaves and berries. The wood turtle is especially fond of cherries.
The aquarium should always have in it a stone or some other object projecting above the water, so that the turtle may climb out, if it chooses. In winter, turtles bury themselves in the ooze at the bottom of ponds and streams. Their eggs have white leathery shells, are oblong or round, and are buried by the mother in the sand or soil near a stream or pond. The long life of turtles is a well authenticated fact, dates carved upon their shells show them to have attained the age of thirty or forty years.
The following are, perhaps, the most common species of turtles:
(a) The Snapping Turtle—This sometimes attains a shell 14 inches long and a weight of forty pounds. It is a vicious creature and inflicts a severe wound with its sharp, hooked beak; it should not be used for a nature-study lesson unless the specimen is very young.
(b) The Mud Turtle—The musk turtle and the common mud turtle both inhabit slow streams and ponds; they are truly aquatic and only come to shore to deposit their eggs. They cannot eat, unless they are under water, and they seek their food in the muddy bottoms. The musk turtle when handled, emits a very strong odor; it has on each side of the head two broad yellow stripes. The mud turtle has no odor. Its head is ornamented with greenish yellow spots.
(c) The Painted Terrapin, or Pond Turtle—This can be determined by the red mottled border of its shell. It makes a good pet, if kept in an aquarium by itself, but will destroy other creatures. It will eat meat or chopped fish, and is fond of earthworms and soft insects.
(d) The Spotted Turtle—This has the upper shell black with numerous round yellow spots upon it. It is common in ponds and marshy streams and its favorite perch is, with many of its companions, upon a log. It feeds under water, eating insect larvæ, dead fish and vegetation. It likes fresh lettuce.
(e) The Wood Terrapin—This is our most common turtle; it is found in damp woods and wet places, since it lives largely upon the land. Its upper shell often reaches a length of six and one-half inches and is made up of many plates, ornamented with concentric ridges. This is the turtle upon whose shell people carve initials and dates and then set it free. All the fleshy parts of this turtle, except the top of the head and the limbs, are brick-red. It feeds on tender vegetables, berries and insects. It makes an interesting pet and will soon learn to eat from the fingers of its master.
(f) The Box-Turtle—This is easily distinguished from the others, because the front and rear portions of the lower shell are hinged so that they can be pulled up against the upper shell. When this turtle is attacked, it draws into the shell and closes both front and back doors, and is very safe from its enemies. It lives entirely upon land and feeds upon berries, tender vegetation and insects. It lives to a great age.
(g) The Soft-shelled Turtle—These are found in streams and canals. The upper shell looks as if it were of one piece of soft leather, and resembles a griddle-cake. Although soft-shelled, these turtles are far from soft-tempered, and must be handled with care.
Leading thought—The turtle's shell is for the purpose of protecting its owner from the attack of enemies. Some turtles live upon land and others in water.
Method—A turtle of any kind, in the schoolroom, is all that is needed to make this lesson interesting.
1. How much can you see of the turtle when it is walking? If you disturb it what does it do? How much of it can you see then? Can you see more of it from the lower side than the upper? What is the advantage to the turtle of having such a shell?
2. Compare the upper shell with the lower as follows: How are they shaped differently? What is their difference in color? Would it be a disadvantage to the turtle if the upper shell were as light colored as the lower? Why? Make a drawing of the upper and the lower shell showing the shape of the plates of which they are composed. Where are the two grown together?
3. Is the border of the upper shell different from the central portion in color and markings? Is the edge smooth or scalloped?
4. How far does the turtle's head project from the front of the shell? What is the shape of the head? With what colors and pattern is it marked? Describe the eyes. How are they protected? How does the turtle wink? Can you discover the little eyelid which comes up from below to cover the eye?
5. Describe the nose and nostrils. Do you think it has a keen sense of smell?
6. Describe the mouth. Are there any teeth? With what does it bite off its food? Describe the movement of the throat. Why is this constant pulsation?
7. What is the shape of the leg? How is it marked? How many claws on the front feet? Are any of the toes webbed? On which feet are the webbed toes? Why should they be webbed? Describe the way a turtle swims. Which feet are used for oars?
8. Describe the tail. How much can be seen from above when the turtle is walking? What becomes of it, when the turtle withdraws into its shell?
9. How much of the turtle's body can you see? What is its color? Is it rough or smooth?
10. What are the turtle's enemies? How does it escape from them? What noise does the turtle make when frightened or angry?
11. Do all turtles live for part of the time in water? What is their food and where do they find it? Write an account of all the species of turtles that you know.
12. How do turtle eggs look? Where are they laid? How are they hidden?
Supplemental reading—"Turtle Eggs for Agassiz," Dallas Lore Sharp, Atlantic Monthly, Feb., 1910.