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Soft Shell Clam

Artwork by: Joann Wheeler, 1999

Fast Facts:

The Latin word "Mya" translates into "a sea mussel" and "arena" translates into "sand." Maryland exports roughly 90% of Chesapeake Bay's harvest to New England.  An adult soft shell clam can filter up to four liters of water per hour!

Size Up to 6 inches.
Habitat Soft shell clams are found buried in mixtures of sand/mud and mud/gravel where salinity is reduced by freshwater runoff and seepage. Soft shell clams can tolerate a variety of salinities (5-30 ppt), which makes them well adapted to estuaries. They can live in areas of low dissolved oxygen for short periods of time. Soft shell clams can often withstand below freezing temperatures.
Reproduction Soft shell clams are capable of reproduction after their first year of life and reproduce by spawning. Spawning is triggered by the increase in water temperature. Once the eggs are fertilized, free swimming larvae develop within a few hours. Despite their free swimming abilities, they are still susceptible to currents, winds and wave action that can disperse them great distances from the site of fertilization. The larval period generally takes one to three weeks but is greatly influenced by water temperature. Larvae metamorph into the juvenile stage and resemble small adults. Juveniles crawl along the bottom sediments looking for suitable substrates. Once they find a suitable substrate (good food resources, low predation and low wave action), they dig into the sediments with their muscular foot. While small, they can re-emerge and search for other suitable substrates. However, when soft shell clams become larger, the remainder of their life is spent sessile beneath the sediments. Adults can be buried a foot or more under the sediments.
Feeding Like all other bivalves, soft shell clams are filter feeders extracting their food (e.g., phytoplankton) from the water column. Soft shell clams have two tubes, called siphons, that work together to strain out food particles from the water column. Water is pumped through one siphon, passed over the gills where food particles collect, and pumped out the other siphon.
Predators Animals that eat soft shell clams are quite numerous and include several species of crabs including the blue crab (Callinectes sapidus) and horseshoe crab (Limulus polyphemus), snails, starfish, fish such as killifishes (Fundulus spp.), and waterfowl such as black ducks (Anas rubripes).
Description Soft shell clams have thin brittle shells and a distinguishing leathery tube that encases their well developed and retractable siphons. The elliptical white shell has a spoon shaped depression inside the left valve at the hinge, while the other valve has a projecting tooth that fits into the depression. Soft shell clams can live up to 12 years in Massachusetts.
Other facts: When disrupted, soft shell clams eject a spurt of water and withdraw to a safer depth in the sediments. This squirting behavior has earned them the nickname "piss clam."

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