Forest Preserve District of Cook County, Illinois
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Aquatic Turtles
Nature Bulletin No 632   march 11, 1961
Forest Preserve District of Cook County
Daniel Ryan, President
Roberts Mann, Conservation Editor
David H. Thompson, Senior Naturalist

AQUATIC TURTLES
Turtles are old and conservative. All other living reptiles -- crocodiles, lizards and snakes -- came along much later So did birds and mammals. The group was already ancient when the giant dinosaurs made their appearance, ruled the animal kingdom during the Age of Reptiles, then became extinct. The turtles merely smiled their toothless smile and slowly went their way. With a shell that is both a house and a suit of armor, they have survived 200 million years with very few changes.

Five species of aquatic turtles are more or less common in the Chicago region and three others are rare. One or more kinds can be found in each of over a hundred bodies of water in the forest preserves.

The snapping turtle is largest -- adults ordinarily weigh over ten pounds and sometimes twenty or even thirty. Colored a drab brown or black, it has a big head, a long tail and a short temper. The musk turtle, or stinkpot, also has a large head and a drab color but its back is highly arched and it never reaches a half pound in weight The name comes from its disagreeable odor. The gentle Blanding's turtle might be called a semi-box turtle because the front half of its lower shell is hinged so that it can be closed to protect the head and forelegs. The throat is bright yellow and the back is black with hundreds of yellowish flecks. The small, lively, painted turtle is the most numerous and widespread of all turtles and the kind most commonly caught locally for pets. The legs, tail and sides of the head are streaked with yellow or red and the edge of the upper shell is blotched with red. The soft-shelled turtle's name is a giveaway -- it feels like a piece of rubber. It has a long flexible snout and a flattened streamlined body.

The turtles started out as land animals and the kinds that live in water give a clue to their ancestry by coming ashore to lay their eggs. Their nesting habits are much the same. In June or July the mature females come out on land and dig a hole -- sometimes near the water's edge, in the case of musk turtles, and sometimes on a dry hillside, as in the painted turtles. The nest cavities are scooped out with the hind feet, narrow above and wider below. After the eggs are laid, the hole is refilled with soil and tamped firmly. She returns to the water and does not come back. After two or three months the eggs hatch and the young, now the size of 25-cent pieces, dig out and find their way to water. Some of the baby painteds stay in the ground until the following spring. Turtle eggs are white with tough leathery shells. Most kinds have oblong eggs but those of the snapper and the soft-shell are round as Ping-Pong balls and bounce almost as well.

In autumn when the water begins to get cold these aquatic turtles burrow into the bottom mud where they spend the winter under the ice cover of lakes, ponds and streams. Snapping turtles often creep into the underwater entrances of muskrat houses or beneath sunken logs. Their life processes slow almost to a halt. They do not eat, they do not use their lungs, they move very little, and the heart beats only at long intervals. What little oxygen they need is absorbed through the lining of the mouth and throat. This is true hibernation.

On warm spring days we begin to see turtle noses poking out of the water to get a breath of air, and Painted turtles, sometimes stacked two-deep on logs, bask in the sun. Crayfish, insects, snails, worms, carrion and water plants are their principal foods. Only the snapper adds fresh fish to its diet. Experiments show that they see colors from red to blue about the same as we do. When caught, numbered and carried across a lake, they promptly return to their home neighborhood.

The turtle maketh progress only when he sticketh out his neck.


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