The Geology of Delaware

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Bivalves: Phylum Mollusca, Class Bivalvia

Mollusca Bivalvia - Miocene Fossils <br>Source:  Wikimedia Commons

Clams, mussels, oysters, and scallops are members to the class Bivalvia (or Pelecypodia). Bivalves have two shells, connected by a flexible ligament, which encase and shield the soft vulnerable parts of the creature. All 15,000 known species of bivalves are aquatic in nature, with close to 80% being marine (saltwater environments).

Living at the bottom of the marine environment bivalves tend to either swim using their mantle cavity to force water movement, burrow into the sand, or attach themselves to an object with sticky strings called "byssal threads."

Below is a list of notable Bivalve species found at the Pollack Farm site.

  • Dallarca sp.
  • Astarte distans
  • Astarte sp.
  • Cyclocardia castrana
  • Glossus sp.
  • Iphigenia sp.
  • Caryocorbula subcontracta

Click the image or the link below to view the bivalvia collection!


Photographs from DGS Special Publication No. 21, 1998, R.N. Benson, ed.
Top left image: http:/

Photo Gallery
6-7. Dallarca (?) subrostrata<br>8-10. Dallarca sp.
1,3. Glycymeris parilis (Conrad)<br>2. Modiolus ducatellii (Conrad)<br>4. Mytilus (Mytiloconcha) incurva (Conrad)
7,9. Glycymeris parilis (Conrad)<br>8. Isognomon (Hippochaeta) sp.
3-4, Pecten humphreysii woolmani (Heilprin)<br>5-8. Crassostrea virginica (Gmelin)
4,8,9. Carditamera aculeata (Conrad)<br>5-7. Parvalucina crenulata  (Conrad)
1-3. Stewartia anodonta (Say)
1-2. Astarte distans  (Conrad)<br>3-6. Astarte sp.
7-8. Dinocardium sp.<br>9,11. "Cardium" calvertensium (Glenn)<br>10. Chesacardium craticuloides (Conrad)
7-8. Ensis directus (Conrad)<br>9-11. Strigilla sp.
9. Donax idoneus ssp.<br>10. Iphigenia sp.<br>11-14. Domax sp.
1-3 Mytilopsis erimiocenicus (Vokes)<br>4. Glossus sp.
3,6. Caryocorbula subcontracta (Whitfield)<br>8,11. Bicorbula idonea (Conrad)<br>9,12. Varicorbula elevata  (Conrad)
4-8. Martesia ovalis (Say)<br>6. Martesia ovalis borings into a broken Mercenaria shell.
1. Thovana  sp., Exterior view of left valve.<br>2-3. Martesia ovalis (Say). <br>2. Close-up view of same specimen in figure 3.<br>3. Exposed hinge of a complete specimen in place in a boring into Crassostrea virginica.