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Soft Shell Clam

Mya arenaria

Unlike most other clams, soft shell clams cannot completely retract their siphons into their shells. (Dave Cowles/Rosario Beach Marine Laboratory)
Unlike most other clams, soft shell clams cannot completely retract their siphons into their shells. (Dave Cowles/Rosario Beach Marine Laboratory)

The soft shell clam is a bivalve with thin, elongated shells. It lives buried in soft sediments in the middle Chesapeake Bay.

Appearance:

  • Thin, oval, elongated shells
  • Shells are chalky white with a thin, brittle covering that varies in color from brownish to gray
  • When closed, the shells gape open at both ends. A foot and two long, leathery siphons protrude from either end.
  • Left shell has a spoon-like depression at the hinge, which the right shell fits into
  • Grows 3-4 inches

Habitat:

  • Burrows deeply in soft sediments from the shoreline to a depth of about 20 feet
  • Spends its entire adult life in one place, unless disturbed

Range:

  • Widely distributed throughout most of the Chesapeake Bay
  • Concentrated in the middle Bay, from Eastern Bay to Pocomoke Sound on the Eastern Shore and from the Severn River to the Rappahannock River on the western shore

Feeding:

  • Filter feeder
  • Draws in water through one siphon, then filters out plankton from the water. Unused water and particles are ejected through the other siphon.

Predators:

  • Adult soft shell clams have many natural predators, including raccoons, blue crabs, horseshoe crabs, diving ducks and cownose rays
  • Humans harvest soft shell clams commercially

Reproduction and Life Cycle:

  • Usually spawns twice per year: once in late spring and once in mid- to late autumn
  • Both eggs and sperm are released into the water column. The number of eggs a female releases depends on its size.
  • Eggs develop into larvae within one day of being fertilized
  • Larvae swim freely for about 1-3 weeks. During this time they develop a foot and shells.
  • Larvae eventually find a suitable place to settle and anchor themselves to the bottom using thin threads secreted from a gland on the foot
  • Juvenile soft shell clams can be very active. Eventually they find a permanent place to burrow.
  • Some soft shell clams have been known to live 12 years

Other Facts:

  • Adults can only move vertically and cannot rebury themselves if removed
  • Unlike most other clams, soft shell clams cannot completely retract their siphons into their shells
  • When disturbed, soft shell clams squirt water out of their siphon

Sources and Additional Information:




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