The spotted turtle averages three and one-half to four and one-half inches in length. It has yellow spots on a black shell. The spots often appear to be "painted" on. The shell has a large, immovable plastron (lower shell) that is dark in color. The turtle's head has scattered yellow spots on the upper side.
The spotted turtle is found in sedge meadows associated with prairies and marshes. It prefers clear, shallow water with many aquatic plants. The spotted turtle is aquatic, but it is often found on land near ponds or streams. The female deposits one to four eggs in June in a nest she digs in a sunny area. The eggs hatch in late September. This turtle eats primarily animals but may ingest plants, too.
Loss of habitat due to the growth of urban areas is the main cause of the species' endangered status, although natural succession of wetland areas can also affect it. Three populations of spotted turtles are known in Illinois, and two of them are protected.