Clams and Mussels

Highlights Found in slow moving, warm rivers Empty shells are often seen piled along a river shoreline Can tolerate degraded environments

• Phylulm Mollusca
• Class Bivalvia

Appearance

• Freshwater clams look basically like those found along an ocean shore
• Body enclosed within two shells (bivalve) held together by a hinge
• Soft, fleshy body (foot) may extend from the open shell
• Empty shells (dead clams) are sometimes found
• Shells are oblong with a brownish yellow, fibrous exterior
• Clams are small, round and symmetrical
• Mussels are larger, oblong and lopsided

Behavior

• Common in the slower sections of the lower Red Deer River, Beaver River, South Saskatchewan River and North Saksatchewan River
• Associated with large rivers having mud or sand bottom
• Clams are mainly sedentary (stationary) and wait for food to pass by them
• Some movement is accomplished by opening the shell, extending the foot and hunching forward little by little
• Shells are open during feeding and closed when disturbed

Aquatic Habitat

• Warm, brown and slow moving rivers

Reproduction

• Hermaphroditic- both sexes in one individual
• May live for up to 20 years

Feeding Type

• Filter feeders on microscopic material adrift in the current
• Diet consists of plankton and organic debris

Predation

• Clams are eaten by river otters, muskrats, raccoons and sturgeon
• Piles of empty shells can be seen along the banks of the Beaver River near Cold Lake. It is thought that river otters carry these clams onto the shore, eat them and discard the shells.
• Clams have been occasionally snagged in the Owl River by anglers casting for pike
• It's fun to collect the shells and check for "mother of pearl" spots on the inside

Pollution Tolerance

• Can be found in slow moving, warm water
• Can tolerate degraded environments
• Moderately pollution tolerant
• Large numbers may indicate fair water quality
• Empty shells do not necessarily reflect water quality because they last so long