VCSU Macro-Invertabrate Lab
Main Key
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).
Spiral shell of Gastropoda Cup-shaped shell of Gastropoda Gastropoda body
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.
Hinged Bivalve shell Soft Bivalve body Bivalve shell
This web site is funded by Region VIII EPA Section 319 funds administered by the North Dakota Department of Health.
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