Field Guide

The St. Francis River crayfish is rather small and dark brown, with blackish blotches or specks over the upper surfaces of the pincers, carapace, and abdomen. It is limited to the St. Francis River and its tributaries.

The gray-speckled crayfish is gray with numerous greenish-black speckles and blotches. A pair of large blotches are present near the back of the head, and another pair occur where the carapace joins the abdomen. In Missouri, it is found only in the southeastern section.

Adult White River crawfish are usually a deep burgundy red with a black V-shaped stripe on the abdomen. Juveniles are gray with dark spots scattered over the carapace. In Missouri, this species mostly occurs in the Bootheel and north along the Mississippi River.

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.

Most people are repulsed by leeches. But once you get past the fact that many species are parasitic bloodsuckers, you will discover that they are fascinating creatures with an important role in nature.

Bryozoans are tiny, filter-feeding invertebrates. They create colonies that can be mossy, branching, or round and jellylike.