Bivalves

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

Astartidae

off west coast Vancouver Is., BC San Juan Islands, WA

Astarte compacta Carpenter, 1864
Compact Astarte
subtidal, 10-200m Puget Sound, WA to the central Aleutian Islands, AK size to 30mm
This species has low, broad commarginal ribs with a thick hinge plate and large teeth. The periostracum is generally light brown and silky. The hinge teeth are large.
(synonym - Astarte willetti)

Pribilof Islands, AK Kasitsna Bay, AK

Tridonta borealis Schumacher, 1817
Boreal Astarte
intertidal to 50m size to 55mm
north central BC to Arctic; througout Bering Sea; Circumboreal
This species has small commarginal ribs near the early portion of the shell and a thick, olive- brown to black periostracum.
(synonym - Astarte borealis)

Tunstall Bay, BC Masset, Haida Gwaii, BC

Astarte esquimalti (W. Baird, 1863)
Wavy-Line Astarte
subtidal, 50-200m Puget Sound, WA to the Beaufort Sea and west to Sea of Okhotsk size to 23mm
This species has variable sculpture, from distinct wavy irregular ribs to fine, only slightly irregular ribs, to a nearly smooth surface with only a few wavy ribs near the umbones. The periostracum may be tan to black.
(previous name - Crassatella esquimalti)

Kasitsna Bay, AK
Tridonta elliptica (Brown 1827)
Elliptical Astarte
subtidal 20-250m size to 35mm
circumboreal; northern Alaska to Puget Sound, WA and
also south to the UK, Massachusetts and the Sea of Japan
This species has prominent, widely spaced, commarginal
ribs. The beak is pointed distinctly toward the anterior side.
(synonyms - Astarte elliptica,Crassina elliptica, Astarte alaskensis)

Barkley Sound, BC
Glans carpenteri (Lamy, 1922)
Carpenter Carditid
intertidal to 100m size to 15mm
northern Mexico to northern BC
This species is infrequently found intertidally.
The distinctive shell is small and elongated.
It has about 14 robust radial ribs.
(synonyms - Lazaria subquadrata,
Cardita subquadrata)

Carditidae

San Juan Islands, WA off central BC coast

Coanicardita ventricosa (Gould, 1850)
Stout Carditid
subtidal, 20-450m size to 27mm
northern Mexico to central Alaska
This species has about 20 low, broad radial ribs overlain with
commarginal ribs. The periostracum is light to dark brown.
This is the most abundant species on the temperate eastern
Pacific Coast. There are three geographic subspecies.
Cyclocardia ventricosa ventricosa occurs from central California
to central Alaska. C. ventricosa montereyensis and
C. ventricosa redondoensis are the more southern subspecies.
(synonyms - Cyclocardia ventricosa ventricosa, Cardita ventricosa)

Esperanza Inlet, BC
Miodontiscus prolongatus (Carpenter, 1864)
Elongate Carditid
subtidal, 5-210m size to 12mm
southern California to central Alaska; also the Kuril Islands
to northern Japan, but not reported from the Aleutian Islands
This species has about 10 broad, shallow radial ribs with
narrow interspaces. It sometimes has deep commarginal
growth lines.
(synonyms - Miodon prolongatus, Venericardia yatesi,
Miodontiscus meridionalis)

Kodiak, AK
Cyclocardia crassidens
(Broderip & Sowerby, 1829)
Thick Cardita
subtidal, 1-200m size to 40mm
Quadra Is., BC to north Alaska and across to Kamchatka and north Japan
This shell may be very thick and slightly variable in shape. The periostracum is thick and relatively smooth.
(synonyms - Astarte crassidens)

Family Astartidae & Carditidae