Download Atlantic Surf Clam

Atlantic Surf Clam
Common Nicknames: Surf clam
Scientific name: Spisula solidissima
Field Markings: Shell is yellowish-white to dark gray, with
a brownish-black covering.
Size: Up to 6 inches long. Siphons can extend several
inches outside the shell.
DISTINGUISHING FEATURES AND
BEHAVIORS
The Atlantic surf clam is one of the largest species of clam
inhabiting the Atlantic coast. Their heavy shells have a rounded,
triangular shape, and the shell surface is
smooth with fine concentric lines. New lines
are added as the clam grows and can therefore
be used to determine its age.
Surf clams have two short siphons which,
when extended into the water column, are used
to collect and expel water and plankton. The
foot of the clam is used for movement. Surf
clams burrow just below the surface of the
mud and are often exposed at low tide, making
them vulnerable to predation.
Surf clams are filter feeders, using one of
their siphons to take in water and plankton. The other siphon
isused to expel water after the plankton and oxygen have been
removed. The gills extract oxygen and collect plankton on mucuscoated cilia. The cilia also send food particles to the mouth. The
clam holds its shell tightly shut with two large muscles, called
adductor muscles. These muscles are strong enough to prevent
most predators from opening the shell.
Surf clams are preyed upon by gulls, who often drop them
Habitat: Intertidally and subtidally, burrowed in sand or mud
from the low tide line to 100 feet of water; beach shorelines.
Seasonal Appearance: Year-round
from the air onto hard surfaces such as boat decks, docks and
parking lots in an effort to break open the shell. Other predators
include whelks and sea stars.
RELATIONSHIP TO PEOPLE
Surf clams make up about 70% of all
clams commercially harvested in the
United States. Only the abductor muscle
of this clam is edible. The are used
primarily in the production of canned
clams and clam chowder and also as fish
bait. These clams are harvested in
offshore waters up to 100 feet deep.
Empty shells are common along the
southern beaches of Rhode Island and
are prized among beachcombers.
During the 1996 North Cape oil spill off Moonstone Beach,
hundreds of thousands of surf clams washed ashore in great
masses, killed by the toxic oil.
HOW TO GET YOUR OWN COPY
RISAA members can purchase their own copy of The
Uncommon Guide To Common Life on Narragansett Bay
for $15 from the RISAA Merchandise Committee. Stop by
the committee table at any monthly RISAA meeting.
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R.I.S.A.A. / November, 2014