Bivalves

Victoria, BC
Macoma calcarea (Gmelin, 1791)
Chalky Macoma
subtidal, 10-360m size to 60mm
Panarctic & Circumboreal, reaching south to central Oregon, Japan, New York, Iceland, and Norway
This shell has a chalky surface. The pallial sinus is very deep in the left valve and moderate in the right. Both are significantly detached.

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

Birch Bay, WA
Macoma balthica (Linnaeus, 1758)
Baltic Macoma *
intertidal to 40m size to 45mm, but usually less than 30mm central California to northern Alaska; panarctic & circumboreal; reaches south to Georgia, Spain & Japan
This is a common shell on beaches of silt or mud. It can be white to yellow or shades of pink. The pallial sinuses are deep and not detached in both valves. Recent studies show Macoma petalum is also be present on the west coast. More study is needed to determine the extent of each. They have basically identical morphology.
(synonyms - Tellina balthica, Macoma inconspicua)

San Juan Islands, WA
Macoma elimata
Dunnill & Coan, 1968
Beveled Macoma
subtidal, 9-435m size to 35mm
southern California to the Aleutian Islands, Alaska
This shell has a definite bend to the "nose". The pallial sinuses are both mostly detached, reaching very deep into the shell in the left valve and moderately deep in the right valve.

San Juan Islands, WA
Macoma carlottensis
Whiteaves, 1880
Charlotte Macoma
subtidal to 1550m size to 30mm
northern Mexico to northern Alaska
This shell has a greenish, polished periostracum. The shape can be quite variable. Both pallial sinuses are moderate and mostly detached.
(synonyms - Macoma inflatula, Macoma quadrana)

San Juan Islands, WA
Macoma brota Dall, 1916
Heavy Macoma
subtidal, 10-260m size to 75mm
Puget Sound, WA to northern Alaska
This is a thick shelled species with a slight curve to the shell at the "nose". The pallial sinuses are mostly detached in both valves, running deep in the left valve and moderate in the right.

Makah Bay, WA
Macoma expansa
Carpenter, 1864
Expanded Macoma
intertidal to 30m size to 50mm
southern California to central Alaska
This shell has a somewhat inflated profile. The pallial sinuses in both valves are moderate and not detached. It tends to be found on more exposed shores.

both - Birch Bay, WA freshly dug from sand

Macoma nasuta (Conrad, 1837)
Bent-Nose Macoma *
intertidal to 50m northern Mexico to southern Alaska size to 110mm
This is very commonly found intertidally in sand or silt. It has a very noticeable bend to the "nose". The pallial sinus in the left valve extends
all the way across the valve. In the right, it is very deep and not detached.

Macoma golikovi Scarlato & Kafanov, 1988
Oval Macoma
intertidal to 200m size to 50mm
Puget Sound, WA to northern Alaska; Sea of Japan to Sakhalin Island
This is a rather oval shaped shell. It is commonly found intertidally in its northern range and tends to be subtidal to the south. The pallial sinuses are slightly detached, reaching very deep in the left valve and moderately in the right. This species was originally confused with the Asian species, Macoma incongrua.

San Juan Islands, WA
Tellina carpenteri
Dall, 1900
Carpenter's Tellin
intertidal to 823m size to 25mm
northern Mexico to southern Alaska
This is infrequently found intertidally.
It is usually tinged pink with two
yellow stripes. It is most easily
confused with A. modesta, but lacks
the internal, radial riblet.
(synonyms - Angulus carpenteri, Tellina variegata)

Ocean Shores, WA
Tellina bodegensis
Hinds, 1845
Bodega Tellin
intertidal to 100m size to 60mm
northern California to southern AK
This is occasionally found
intertidally along the open coast.
The interior is often tinged pink or
yellow. It is a thick, solid shell.

Macoma inquinata (Deshayes, 1855)
Pointed Macoma *
intertidal to 50m size to 55mm
southern California to central Alaska
This is very commonly found intertidally. It prefers a silty habitat and is often stained a dirty color. The pallial sinuses are not detached and extend very deep across the valves. This species was originally confused with Macoma iris.

Macoma lipara Dall, 1916
Sleek Macoma
subtidal, 20-260m size to 75mm
southern California to northern Alaska
This is a heavy shell. The pallial sinuses are mostly detached, reaching deeply into the left valve and moderately in the right.

Oak Bay, WA
Tellina nuculoides
(Reeve, 1854)
Salmon Tellin
intertidal to 75m size to 20mm
northern Mexico to central Alaska
This is infrequently found intertidally. It is has an olive-colored, shiny periostracum and the shell can be
white to pink. Rather than the silt or sand most of our Macomas andTellins are found in, this one likes a coarser sand or even rocky location.
(synonym - Tellina salmonea)

Oak Bay, WA
Tellina modesta (Carpenter, 1864)
Plain Tellin *
intertidal to 100m size to 20mm
northern Mexico to central Alaska
This is somewhat commonly found intertidally
on sandy beaches. The shell is usually glossy
white. It has an internal, radial riblet.
(synonyms - Angulus modesta, Tellina buttoni)

Macoma yoldiformis
Carpenter, 1864
Yoldia Shape Macoma
intertidal to 100m size to 25mm
northern Mexico to southern, Alaska
This is rarely found intertidally in the northwest. Its shape is reminiscent of a Yoldia, hence the name. The pallial sinuses reach about halfway across the valves. It is mostly detached in the left valve and moderately detached in the right. It prefers protected waters.

Semiahmoo Spit, WA Thetis Island, BC submerged in water, siphon partly extended

Macoma secta (Conrad, 1837)
White-Sand Macoma *
intertidal to 50m size to 120mm
northern Mexico to northern BC
This is commonly found intertidally in sandin sheltered locations. It is our largest
intertidal species and has a noticeably small, thick ligament for the size of the shell. The posterior end has a distinct ridge. The pallial sinuses are not detached and reach
deeply across the valves. It is hard to confuse this species with any of our other Macomas.
(previous names - Tellina secta)

Family Tellinidae