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 woodland crayfish is stout, reddish tan to dark brown, with numerous blackish specks and blotches on the pincers, carapace, and abdomen. It occurs only in Missouri, especially in the Black River and its tributaries.

The Ozark crayfish is light brown to reddish brown with numerous black specks on the pincers and often on the abdomen as well. The pincers are broad and powerful. It lives in the White and Black stream systems.

The Big Creek crayfish is moderately small and brown. It has a very localized distribution centered in Big Creek and its tributaries, in the St. Francis River basin. It lacks bright colors, but blackish specks and blotches occur over the top surfaces of the body and pincers.

The saddleback crayfish has a bold blackish band across the hind margin of the carapace and lacks dark blotches or specks. The pincers are broad and powerful. It occurs in the Big and Meramec river drainages.

Often overlooked by people, but eagerly sought by fish, Missouri’s amphipods resemble shrimplike sowbugs. Scuds live in various aquatic habitats, and several species inhabit caves.

Everyone knows about terrestrial sowbugs and pillbugs, but many isopod species are aquatic. Missouri has several isopods that live in streams, ponds, rivers, and caves.

The coldwater crayfish has a very localized distribution in the Eleven Point River system. It is stout, with a blue-green head and pincers and dark, rust-brown carapace. It is an imperiled species.

These small mussels use darters, a type of fish, as hosts for their young.

These diminutive mollusks are the smallest of Missouri’s freshwater mussels.