This key covers the 2 classes of Mollusca that we have collected in North Dakota rivers and streams. This key aids by providing sample features you can look for to identify your specimen. After using the key, confirm the identity of your specimen by reading the class page..
Gastropoda (snails) - Gastropods have a single, spiral shell (Fig. 1). Or occasionally have a single, cup-shaped shell (Fig. 2). The soft body inside has a head region (Fig. 3).
Bivalvia (mussels) - Bivalves have a shell in two parts, connected by a hinge (Fig. 4). The soft body inside lacks a head (Fig. 5). Overall appearance as in Figure 6.