Forest Preserve District of Cook County (Illinois)
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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