Field Guide

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.

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.

Pulmonate, or lunged snails breathe via a lunglike pulmonary cavity, and they lack the hard trapdoor-like operculum found in gilled snails. Except for in the Ozarks, pulmonate snails predominate in most of the aquatic regions in our state.

Of Missouri’s two species of freshwater shrimp, the Ohio River shrimp is certainly the rarest. It was thought to be extirpated from our state but was rediscovered recently in the Mississippi River.

The elktoe is one of many Missouri mussels with a declining population.

Groups of whirligig beetles swim on the water surface in quick, random patterns, searching for food. They have two pairs of eyes — one pair above water, one pair below — to help them quickly and accurately capture their prey.

You may have heard about stinging jellyfish in the ocean, but did you know that there are similar creatures living in the freshwater of Missouri? Fortunately, they’re harmless!