Feeding & growth
  Like other bivalves, scallops feed on phytoplankton that they sieve from the water on their gills. Particles move along the gill edges in ciliated grooves and are sorted by the paired labial palps on either side of the mouth. Edible material moves along ciliated tracts into the mouth while inorganic and other inedible matter is gathered by the palps into mucousy blobs and these, along with feces, are periodically ejected from the mantle cavity by rapid clapping of the shell valves.
Research study 1

Two specimens of Chlamys sp. poised to swim. It is almost impossible to
distinguish the west-coast species C. hastata and C. rubida in the field,
especially when they are coverered with sponge or other growth 1X

A scallop Chlamys sp. of 8cm shell height is about 8yr old. Divers should think twice about removing rock scallops Crassadoma gigantea to eat.  A specimen of 17cm shell height may be 20-25yr old. MacDonald et al. 1991 Can J Fish Aquat Sci 48: 215.

Purple-hinge rock scallop Crassadoma gigantea 0.7X

Research study 2

photograph showing a rock scallop excessively fouled with hydroids, anemones, and algaeA study on growth of purple-hinge rock scallops Crassadoma gigantea at Mission Bay near San Diego, California shows that test specimens grow best in deeper depths.  At a depth of 1m, for example, excessive fouling growth apparently interferes with growth.  Monical 1980 Proc Nat Shellfish Assoc 70: 14.

NOTE  test scallops are suspended in cages at 1, 4, and 6m below MLLW







Rock scallop Crassadoma gigantea excessively
fouled with hydroids, anemones, and algae 0.7X

Research study 3

graph showing age and growth of scallops Patinopecten caurinusAn investigation in Alaska by scientists from the National Marine Fisheries Service, NOAA shows that growth and size of Pacific sea scallops Patinopecten caurinus increases from sites in the southeast to sites in the northwest (see map and graph).  Age is determined by counting annual (winter) growth rings on the upper (exposed) valve.  photograph of Pacific plate scallop Patinopecten caurinusIgnell & Haynes 2000 Fish Bull 98: 849.

NOTE  data are from scallops collected in 1968 and thus provide a valuable “early-fishery” baseline.  The current fishery commenced in 1967


Pacific plate
scallop Patino-
pecten caurinus

  black dot