Field Guide

Crayfish are freshwater aquatic invertebrates that look a lot like small lobsters, to which they are related. There are about 38 species of crayfish in Missouri.

Unlike their parasitic cousins in the flatworm group, turbellarians, or planarians, are tiny carnivores or detritus-eaters that glide smoothly across submerged leaves and other objects.

The spothanded crayfish is moderately large and usually has a noticeable black spot on each pincer near the base of the movable finger. In Missouri, it is found mostly in Ozark waterways in the southeastern quarter of the state, from Callaway, Montgomery, and Warren counties south.

Gilled snails are one of two main groups of aquatic snails in Missouri (the other group is the "lunged" snails). Gilled snails, or prosobranchs, breathe with gills and possess a hard trapdoor-like operculum. They are most common in the Ozarks.

Williams' crayfish is small and rather plain, without bright colors or bold markings. It has a pale, vase-shaped zone along the middle of the dark olive-tan carapace. It is found only in the upper White River drainage of Missouri and Arkansas.