Bivalves

Click on photo to enlarge. Scale line in photo equals 1cm unless otherwise specified.
* Species which are commonly encountered on the beach.

Lucinoma annulatum
(Reeve, 1850)
Western Ringed Lucine
intertidal to 750m size to 82mm
northern Mexico to central Alaska & Japan
This is occasionally found intertidally.
The prominent growth rings are easily eroded.
On this species the growth rings represent
growth intervals, not years.
(previous name - Lucina annulata)

Boca de Quadra, AK
Adontorhina sphaericosa
P.H. Scott, 1986
Inflated Axinopsid
subtidal, 95-3000m size to 1.6mm
central California to SE Alaska
This tiny shell is highly inflated, almost a round ball. The hinge plate is moderately broad with irregular granules.

Thyasiridae

Pribilof Islands, AK
Adontorhina cyclia S.S. Berry, 1947
Circle Axinopsid
subtidal, 12-3000m size to 3mm
north Mexico to north Bering Sea; Sakhalin Island to southern Kuril Islands
This tiny shell is moderately inflated and has fine granules on the hinge plate.

off central Oregon coast
Thyasira flexuosa (Montagu, 1803)
Flexuose Cleftclam
subtidal, 20-3000m size to 12mm
circumboreal and panarctic; reaches south to
southern California, Florida, north Africa and Japan
The shell form is extremely variable. It has very
fine sculpturing. It has many synonyms, and with
further study, it may be determined there is more
than one species.
(synonyms - Tellina flexuosa, Cryptodon barbarensis, Cryptodon insignis, Cryptodon planus, Axinulus inaequalis)

Gulf of California, Mexico offshore north Washington coast

Channelaxinus excavata (Dall, 1901)
Excavated Cleftclam
subtidal, 800-2520m north Mexico to north Washington size to 24mm
This small deep water shell has a distinct cleft on the anterior end.
(synonyms - Conchocele excavata, Thyasira excavata, Thyasira tricarinata)

off central Oregon coast
Mendicula ferruginosa (Forbes, 1844)
Rusty Axinopsid
subtidal, 40-4475m size to 3.2mm
Circumboreal and Arctic; central California to Pribilof Islands; Cape Hatteras, NC to Georges Bank; Mediterranean; Eastern Atlantic; Cape Verde, Angola and Argentine basins
This widespread species is pale yellow. But it's thin periostracum is usually covered with a thick, reddish-brown coating.
(synonyms - Aligena (Odontogena) borealis, Cryptodon ferruginosum, Axinus ferrugineus, Thyasira ferruginea, Cryptodon rotundatus)

Conchocele bisecta (Conrad, 1849)
Giant Cleftclam
subtidal, 50-750m size to 100mm
northern California to Bering Sea; Sea of Japan to Sea of Okhotsk
This is found on mud bottoms. It is a chalky shell with a prominent cleft on the anterior end.
(synonym - Conchocele disjuncta)

Kasitsna Bay, AK
Axinopsida serricata
(Carpenter, 1864)
Lenticular Axinopsid
low intertidal to 275m size to 8mm
Circumboreal & Panarctic; reaches south to north Mexico, north Japan, & Labrador
This shell can be highly variable in shape. It has a strong central tooth. Lives in mud.
(synonym - Cyptodon serricatus)

Barkley Sound, BC BC

Parvilucina tenuisculpta
(Carpenter, 1864)
Fine-Lined Lucine
intertidal to 300m northern Mexico to northern Alaska size to 15mm
This is infrequently found intertidally. It prefers mud with high organic content. The growth lines are
very fine and closely spaced.
(previous name - Lucina tenuisculpta)

Family Lucinidae & Thyasiridae