Crayfish

On Saturday, we went wading around the ford across the Salt Fork, about one quarter mile upstream (as the crow flies) from the bridge on 1200N at the south edge of Homer Lake Park. We were looking for mussels, and although we didn't find any live ones, we did find these guys, a large one (top, about 2.5-3.0 inches), and a small one (bottom, maybe 1.5 inches) about 10 feet upstream.

We have no experience identifying crayfish (among other things), so if you have any specific knowledge, please add comments. Rob Kanter has a nice post on Appeciating Illinois Crayfish at the Environmental Almanac blog, and the Carnegie Museum of Natural History maintains an extensive database, including information and many photos of Illinois species