Wild About Illinois Turtles!

Two hundred sixty species of turtles occur worldwide. Seventeen of these species inhabit Illinois, dwelling in forests, prairies, marshes, swamps, ponds, lakes, streams and rivers. Those aquatic species that bask are regularly seen on sunny days lining logs and sand banks. Other species are most often encountered in the spring while crossing highways and fields in search of new habitats, mates or nesting sites. The chief conservation issue for turtles is the loss or alteration of critical habitats. Over-exploitation of turtles for food and the pet trade are also serious problems in Illinois.

​Kingdom: Animalia
Phylum: Chordata
Class: Reptilia (lizards, snakes and turtles) - These organisms develop from and amniotic egg, which is either deposited on land or retained within the female for the extent of its development. The egg provides everything the embryo needs to develop. The shell of a reptile egg is leathery. Fertilization is internal. Reptiles are covered in scales, and their skin is dry.
Order: Testudines (turtles) - Turtles are classified in this order. They have a bony or leathery shell.
Family: Chelydridae - The snapping turtle family is composed of two species. These turtles are found only in North and South America. These turtles are aquatic.
     snapping turtle (Chelydra serpentina)
     alligator snapping turtle (Macrochelys temminckii) [state endangered]

Family: Emydidae - The basking, marsh and box turtles are small to medium in size. Most of them are aquatic, but a few species are semi-aquatic or live on land.
     painted turtle (Chrysemys picta)
     spotted turtle (Clemmys guttata) [state endangered]
     Blanding’s turtle (Emydoidea blandingii) [state endangered]
     northern map turtle (Graptemys geographica)
     Ouachita map turtle (Graptemys ouachitensis)
     false map turtle (Graptemys pseudogeographica)
     river cooter (Pseudemys concinna) [state endangered]
     woodland box turtle (Terrapene carolina)
     ornate box turtle (Terrapene ornata) [state threatened]
     pond slider (Trachemys scripta)

Family: Kinosternidae - The mud and musk turtles are found in North and South America. These are small, plain turtles.
     yellow mud turtle (Kinosternon flavescens) [state endangered]
     eastern mud turtle (Kinosternon subrubrum)
     eastern musk turtle (Sternotherus odoratus)

Family: Trionychidae - Softshell turtles may be found in Asia, Africa and North America. These turtles are round and flat. They have a leathery shell. The feet are webbed.
     smooth softshell (Apalone mutica) [state threatened]
     spiny softshell (Apalone spinifera)

​Turtles are members of the Phylum Chordata, Class Reptilia and Order Testudines. Their unique shell (Figure 1), lack of teeth and bony jaws, which are covered with a hard, keratinized beak somewhat like that of birds, make them unusual. A turtle shell has as many as 60 bones. It has two sections: a carapace, covering the animal's back, and a plastron, covering its belly. The carapace and plastron are connected on the turtle's right and left sides by a bony bridge, which is formed by extensions of the plastron. The shell is fashioned from bones originating in the skin, which fuse with one another as well as with the ribs, vertebrae and parts of the shoulder girdle (Figure 2). In most species, large scales, called scutes, overlay the bones. However, in softshell turtles, a tough, leathery skin replaces the scutes.

Most Illinois turtles are able to withdraw their head and neck into the shell by bending the neck into a vertical S-shaped curve. In species such as box turtles and mud turtles, the plastron is hinged, allowing it to close on the carapace. This feature provides the animal with more complete protection. Turtles usually have a prominent tail that vary in size with sex (tails of males are longer and heavier than those of females) and with species (snapping turtles have the longest tails of Illinois species). Turtles use their limbs to propel themselves in water as well as over land. The toes of most species are extensively connected by webbing, an adaptation that aids them in aquatic locomotion.

FIGURE 1 - Outside of carapace with scutes removed

FIGURE 2 - Cross section of turtle showing relationship between skeleton and shell

Illustrations © Illinois Department of Natural Resources. Clint Johnston, illustrator. 

Turtles' courtship and mating commonly occur in the spring and fall. The courtship of pond sliders, painted turtles, false map and northern map turtles consists of the relatively small male swimming backward, ahead of the female, while fanning his elongated front claws in front of her snout. In those species where the female is the smaller sex, the male typically uses aggressive behavior to immobilize the female so that he can obtain a mating position at the back edge of her shell. He may, for example, bite at the female's head and legs. In box turtles, the female's shell is quite high, requiring the male to hook the claws of his hind feet beneath her shell and then rear up into a vertical stance in order to mate.

All turtles must nest on land. Egg-laying typically occurs between mid-May and early July. A nest is usually a flask-shaped hole scooped out with the female's back feet. After egg-laying, the female again uses her back feet to pull dirt into the hole and pack it down. When the nest is covered, she abandons it, never returning to see her young. The yellow mud turtle female is an exception. She digs a nest burrow with her front legs and then remains with the eggs in the burrow for several days to two weeks. Nevertheless, she is long gone by the time the eggs hatch. Most Illinois turtles lay oval eggs, but softshells and snapping turtles lay spherical eggs. Small species, such as the spotted turtle, may lay only three to five eggs in a nest, while the larger snapping turtle lays 20 to 40 eggs. Spotted, snapping and Blanding's turtles lay eggs once per year. Others, including the eastern musk turtle, map turtles, the painted turtle and the pond slider, commonly nest two or three times per year, at two to three week intervals.

The life cycle of the eastern box turtle is typical of most turtles. After mating, the female digs a nest in the soil with her rear legs. She deposits the eggs, then uses her rear legs to cover them with dirt. Hatchlings must dig their way out of the nest. The turtles reach adult stage in five to seven years.

Illustrations © Illinois Department of Natural Resources. Clint Johnston, illustrator. 

​Some turtle species are associated with specific habitats. For example, Illinois' two terrestrial turtles, the eastern box and the ornate box, are associated with woodlands and prairies, respectively. Rivers are the favored habitat of the smooth softshell turtle, alligator snapping turtle and northern map turtle. Blanding's turtles are commonly associated with marshes. Mud turtles tend to frequent temporary ponds or wetlands, while the closely related eastern musk turtle resides in permanent water. The highly adaptable snapping turtle, painted turtle, pond slider and spiny softshell turtle thrive in a variety of habitats and conditions.

Most Illinois turtles are opportunistic omnivores. Even a snapping turtle's diet may include large amounts of plants along with the animal food it usually eats. A few species are chiefly carnivorous or herbivorous. Softshells are carnivores, feeding on aquatic invertebrates, such as aquatic insects. Map turtles feed on snails, clams and some insects. Diets of certain species change with age. For example, young sliders are carnivores, feeding on insects. Adult pond sliders, however, mainly eat plants. Eastern river cooters are mainly herbivorous as adults. Their diet consists of a mixture of algae and plants. Few turtles have the speed or agility to catch fast-moving prey. Most search for food slowly along the bottom or over weed beds, grazing on vegetation and eating slow-moving animals. The occasional dead fish or fruit fallen from a riverside tree may attract large numbers of turtles.

A few species catch fast-moving prey by ambush. Such turtles usually are colored to blend with their environment and have long, muscular necks that can strike out at prey from a distance. A snapping turtle with its long, bumpy neck, mud-colored body and algae-covered shell, illustrates these characteristics well. The softshell turtle's pancakelike shape allows for quick hiding beneath a thin layer of the sand bottom from where it can surprise its prey.

​In Illinois over the last century and a half, humans have cut down much of the forest; converted most of the prairies to agriculture; channeled, dammed and polluted many of the rivers; and drained almost 90 percent of the state's wetlands. Only 11 percent of the original vegetation now remains intact. This drastic alteration of the original habitat has had a major impact on the state's wildlife and plants. In 2020, of the state's 17 turtle species, five (the alligator snapping turtle, the spotted turtle, Blanding's turtle, the river cooter and the yellow mud turtle) are state endangered and two (the ornate box turtle and the smooth softshell) are state threatened. Declines of the latter three can be attributed in part to loss of wetlands. Siltation and channelization of Illinois rivers have seriously affected other species.

Exploitation is another important cause of declining turtle populations. Snapping turtles and softshells are often sought for food in Illinois. While local consumption has not been a serious problem and is regulated by the Illinois Department of Natural Resources, a new concern is the growing demand for turtle meat and products in Asia. Food species (sliders, snappers, softshells) and pet trade species (box turtles, spotted turtles) draw high prices in that market. As Asian species disappear, markets shift to the United States to meet the demand. While a special license is needed to collect turtles in Illinois for commercial purposes, their high asking price makes poaching tempting to some people.

The keys to conserving Illinois' turtles will be the rigid enforcement of current protective laws and the setting aside and maintenance of ample clean, aquatic and terrestrial habitats. If these guidelines are followed, we can expect turtles to remain in our Illinois forests, prairies, wetlands and waterways for many years to come.

river cooter - Illustrations © Illinois Department of Natural Resources. Clint Johnston, illustrator.

​aestivate to become inactive during warm/dry periods of the year

aquatic water based, or living in water

bask to expose the body to the direct rays of the sun (e.g., many species of turtles regularly leave the water to bask on logs or rocks)

carapace the top, or back, portion of a turtle shell

carnivorous feeding on meat (animals)

channelization the straightening and/or deepening of a river channel

cloaca a chamber in the abdomen of some vertebrates that receives products of the reproductive, urinary and digestive tracts before emptying to the exterior through the anus

embryo an organism in its early stages of development

endangered species a species in danger of becoming extinct within all or part of its range

herbivorous feeding chiefly on plants

hibernate become inactive during cold periods of the year

juvenile individual that has not attained sexual maturity

keratin hard, tough, fibrous protein produced in the skin—the basic substance that makes up scales, claws, fingernails and hair

omnivorous feeding on a mixed diet of animals and plants

plastron the belly, or bottom, portion of a turtle shell

scutes enlarged scales such as those covering the bony shell of most turtles

siltation deposition of fine mineral particles (silt) on the beds of streams or lakes

terrestrial land based, or living on land

threatened species a species likely to become endangered

In the wild, aquatic turtles are known to survive from 40 to 70 years while certain terrestrial species (including the eastern box turtle) may live 100 years or more.

The largest Illinois turtle is the alligator snapping turtle. In some locations it may grow to a shell length of 30 inches (77 cm) and a weight of more than 250 pounds (112.5 kilograms). The largest Illinois specimen on record weighed about 160 pounds.

The smallest Illinois turtle is the spotted turtle. Its greatest recorded shell length in Illinois is 4.7 inches (12 cm).

Many species of turtles have temperature-dependent sex determination (TSD). The sex of the embryo depends on the temperature within the nest at a critical period. For these species, hatchlings may be all male or all female.

In Illinois, turtle eggs typically require about two months to hatch. Hatchlings of some species, like painted turtles, overwinter in the nest and do not move to water until the next spring.

Most aquatic turtles hibernate underwater, often burying in the bottom muck. All but the softshells have thin-walled sacks attached to the cloaca that absorb oxygen from the water during winter.

Yellow mud turtles typically inhabit temporary prairie ponds for two or three months in the spring, then aestivate/hibernate on land throughout the rest of the year.

Softshell turtles have a hard, bony shell. Their name refers both to the leathery skin covering the shell (as opposed to hard scutes) and to the rear portion of the carapace that is tough but flexible.

The flesh of eastern box turtles may be poisonous at times because their tissues store toxins of poisonous mushrooms that the turtle may eat.

With age, the shell and skin of male pond sliders become dark in color. The turtles appear dull brown to black, losing the bright colors that characterize females, juveniles and younger adult males.

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