Field Guide

When a floater dies, this large mussel with a thick shell will actually rise to the water surface and float as it decays.

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

Shaped like a checkered gunstock, with its unique, turned-down edge, pistolgrips are easy to identify.

Sometimes called the blue-point, this mussel species is widely distributed in Missouri rivers and is occasionally found along reservoir margins.

The shell of this mollusk is large and impressive in overall size. Although fairly flat, it can be more than 8 inches long. A large wing on the heelsplitter can be painful if you step on it.

Zebra mussels are named for their shells, which have alternating light and dark bands. They are a highly invasive nonnative species. Learn how to prevent their spread.

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.

Ramshorn snails are easy to identify at a glance, because the shell is a flat, disklike coil. Like other pulmonate aquatic snails, they lack the hard horny “trapdoor” possessed by other types of aquatic snails.

At one time the most valuable shell to the commercial button industry, the ebonyshell is now classified as endangered in Missouri and is a candidate for federal endangered status.