Iowa Mussels Identification

Size

• Size can be an unreliable index for identification, since it's hard to account for different levels of maturity and regional variations. Nonetheless, it's a useful characteristic. Some of Iowa's mussels are hefty: the plain pocketbook may be seven inches across. Others are more diminutive, like the threatened, three-inch ellipse.

Shape

• Iowa's mussels come in a variety of shapes, though it takes a keen eye to define these. For example, a giant floater's shell is usually more elongated and oval than the rounder structure of a mapleleaf mussel.

Coloration and Pattern

• Coloration and pattern, like size, are difficult to rely upon, as they shift with age and individual variation. However, paying attention to a mussel's patterning and hue is a natural method of description. The squawfoot mussel, for example, tends to morph from green to dark brown or black between adolescence and adulthood.

Exotics

• Keep an eye out for Iowa's exotic mussels, which were transported by humans from other parts of the world. The zebra mussel, defined by banding and a small, irregular-shaped shell, is the most notorious, but the Asian clam is also seen in Iowa. Both are usually 1.5 inches or less in length.