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| Bay Clams |
A number of clam shell features are used to identify clams. Shape and size are usually coupled with exterior and interior design of shells to positively identfy clams.
Know what you’re digging before your shovel starts working! See information about identifying clams by their show.
Quick reference for bay clams of Oregon (pdf)
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| Common name |
Gaper |
Butter |
Native Littleneck |
Cockle |
| Other names |
Empire, horseneck, blue
Scientific: Tresus capax |
Beefsteak, Martha Washington, Quahog
Scientific: Saxidomus giganteus |
Steamer, native littleneck
Scientific: Leukoma staminea |
Heart cockle, Nutall's cockle
Scientific: Clinocardium nuttallii |
| Key Identification Features |
Large gape around neck and concentric shell rings.
Largest common clam in Oregon estuaries.
Commensal pea crab pairs are often found within their mantle. |
Identified by its smooth concentric rings.
Thick and heavy oval shell |
Identified by concentric lines and radiating ridges
Longer lived and less abundant than cockles.
Circular in shape. |
Identified by their prominent radiating ridges.
Circular in shape. |
| Common size |
3-6" |
2-4" |
1½-2½” |
1½-3”
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| Common habitat |
High salinity areas of sand or mud. |
High salinity areas of sand, mud, gravel, or rock |
High salinity areas of sand, mud, gravel, or rock. |
High salinity areas of sand. |
| Further links |
How to dig
More about gapers |
How to dig
More about butters |
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How to dig
More about cockles |
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| Common name |
Softshell |
Purple varnish clam |
Rough piddock |
Flat tipped piddock |
| Other names |
Mud clam, eastern softshell
Scientific: Mya arenaria |
Mahogony clam
Scientific: Nuttallia obscurata |
Piddock, rock oyster
Scientific: Zirfaea pilsbryi |
Piddock, rock oyster
Scientific: Penitella penita |
| Key Identification Features |
Concentric rings and oblong egg shape, slightly pointed at the neck end. |
Identified by its varnish like coating and purple interior.
Native to Japan, introduced to Oregon in the 1990s. |
Identified by gape at neck end and teeth (for burrowing) at foot end. |
Distinguished from the rough piddock by the "callum"- the smooth area on the lower foot area of the shell. |
| Common size |
2-4" |
1½-3”
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3-5”
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1½-3” |
| Common habitat |
High to low salinity areas of mud. |
Mid salinity areas of sand. |
High salinity areas of clay, mud or sandstone. Most common in high salinity portions of bays. |
Nearshore rocky areas |
| Further links |
How to dig
More about softshells |
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More about Piddocks |
More about Piddocks |
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