Bivalves

Home > Northwest Shells & Marine Life > PNW Shells & Marine Life Photos > Bivalves > Bivalves - Trapezidae, Ungulinidae ,
Kelliellidae & Vesicomyidae

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

Neotrapezium liratum (Reeve,1843)
Quadrate Trapezium
intertidal size to 53mm
introduced to various locations in BC and WA with oyster seed, native to the western Pacific
It is easily found where it is established. The shell is oblong with irregular concentric growth lines. The interior is often purplish. It attaches bysally to rocks
and oyster shells in river estuaries.
(synonyms - Trapezium liratum, Trapezium japonicum)

Ungulinidae

Hope Island, BC Nanaimo, BC, juvenile with intact periostracum

Diplodonta impolita S.S. Berry, 1953
Rough Diplodon
intertidal to 100m Oregon to Kodiak, Alaska size to 32mm
This is occasionally found intertidally. It is fairly round and inflated.
The shell is chalky white under a thick periostracum. It has heavy
irregular, commarginal growth lines. This has sometimes been called Diplodonta orbella, which is now known to be a more southern species. Yet another species exists north of Kodiak, AK.

Kelliellidae

off west coast U.S.
Kelliella sp.
Deep-orb
Kelliella are deep water species. Our specimen is either Kelliella galatheae Knudsen, 1970 or K. pacifica (E.A. Smith, 1885). K. galatheae ranges from BC to the Gulf of Panama at a depth of 1760-4000m. K. pacifica lives on the abyssal plain of the mid-north Pacific Ocean at a depth of 4882-5200m. Our specimen did not have exact location data.

Vesicomyidae

Isla Tortuga, Mexico
Archivesica gigas (Dall, 1896)
Giant Vesicomya
subtidal, 550-2610m size to 125mm
north Mexico to Gulf of Alaska; Costa Rica; central Chile
This species grows large and is very inflated. The periostracum may be light olive to dark brown.
(previous names - Vesicomya gigas, Callocardia gigas)

off Oregon coast
Phreagena kilmeri (F.R. Bernard, 1974)
Kilmer Vesicomya
subtidal, 800-1200m size to 85mm
north Mexico to Haida Gwaii, BC
This species is a little smaller and less inflated than A. gigas but with a thicker shell.
(previous names - Vesicomya kilmeri, Calyptogena kilmeri)

off central Oregon coast
Pliocardia stearnsii (Dall, 1895)
Stearns Vesicomya
subtidal, 370-3070m size to 46mm
north Mexico to Barkley Sound, BC
This species in inflated with prominent beaks. The shell is thin with a light tan periostracum.
(previous names - Vesicomya stearnsii, Callocardia stearnsii)

off Oregon coast
Vesicomya pacifica (E.A. Smith, 1885)
Pacific Vesicomya
subtidal, 550-2000m size to 75mm
Monterey Canyon, CA to Gulf of Alaska; Kurile Trench; Costa Rica subduction zone
This shell is inflated and thicker than P. kilmeri. The periostracum is light brown.
(previous name - Calyptogena pacifica)

Wareniconcha lepta (Dall, 1896)
Thin Vesicomya
subtidal, 850-1920m size to 65mm
north Mexico to Tillamook, OR
This shell is inflated and thin. The periostracum is thick and may be light to dark brown.
(previous names - Vesicomya lepta, Callocardia lepta)

Family Trapezidae, Ungulinidae,

Kelliellidae & Vesicomyidae