Bivalvia

Class Bivalvia (Clams and Mussels) 
Courtesy of the Cacapon InstituteTwo shells opposite of each other and strongly connected by a hinged ligament; the shell is thick and strong or thin and fragile in some kinds; growth rings on the shell are either far apart and are distinctly raised, or very close together and hardly raised at all; the foot usually consists of two tubular structures that can often be seen protruding from the shell; the body is soft tissue, often pinkish or gray in color.  Click-Here to learn about the mussel's life cycle, and Here to learn more about kinds typically found in West Virginia. 

Clams

1.

Corbiculidae (Asian clam): Shell is rounded; brown in color usually lighter than mussels; raised separated ridges along the top and sides of the shell. Clinger/burrower; Collector/filterer; VS-VL (M)(S/F)

2.

Sphaeriidae (Pea clam): Shell is very small and rounded; light colored; ridges spaced close together, not raised. Clinger/burrower; Collector/filterer; VS-M (M)(S/F)

Mussels

3.

Unionidae (Mussel): Largest of the bivalves; shell usually dark in color, variable in shape but maybe somewhat oblong; has many indentations and ridges on the tops and sides of the shell. Clinger/burrower; Collector/filterer; VS-VL (L)(S/F)

4.

Dreissenidae (Zebra mussel): Gets their common name from the striped pattern of their shells, though not all shells bear this pattern; usually about fingernail size but can grow to a maximum length of nearly two inches; often they can be found in large colonies attached to a variety of objects. Clinger; Collector/filterer; VS-M (M)(S)


Note:
North American streams, rivers, and lakes support the richest diversity of freshwater mollusks on the planet. Over 650 species of snails and 300 species of freshwater mussels have been described so far. Click-Here to learn more.  
 

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