The northern map turtle averages seven to nearly 11 inches in length. Its shell is slightly ﬂattened and has a keel (ridge) in the center of the carapace (top of shell). The carapace is green, olive or brown with a dim pattern of lines. The plastron (bottom shell) is yellow with no markings. This animal has a yellow spot behind its eye and yellow lines on the head, neck and tail. The back edge of the carapace has projections like the teeth of a saw.
The northern map turtle may be found statewide in Illinois. It lives in rivers, sloughs and lakes, particularly where the bottom is muddy and plants are present. This reptile is aquatic, coming to land only to lay eggs or to bask in the sun on logs or other objects along the water’s edge. It feeds in the early morning and late evening. It is slow to hibernate and may be seen walking around on the bottom of a water body even when ice covers the water. Courtship and mating occur from March until May. The female digs a nest in soil some distance from the water where she deposits 10 to 16 eggs that hatch in late summer to early fall or as late as the following spring. The female often lays three clutches of eggs per year. The northern map turtle eats mollusks (snails, slugs and others), crayﬁsh and insects.