valves are broader than
long. As is the rule for members of Class Articulata, the
this species cannot be opened fully without breaking the valves. The
opening undulates strongly, involving both valves. The
pedicle valve (ventral) has a slightly elevated median ridge
broadly rounded notch at the anterior margin opposite the pedicle.
The shell’s color may be gray, yellow, tan, brown, or reddish. Width up
to 5.6 cm.
Common lamp shell , transverse
lamp shell, scalloped lamp
|Synonyms: Terebratalia caurina
photo taken at Rosario beach Marine
|Photo by: Anna Dyer,
How to Distinguish
from Similar Species: Distinguished
by location, color, and the fact that it is broader than long. No other
brachiopod or clam in this region has such strong undulations in the
opening between the valves.
Note: Unlike in clams, the two valves of a brachiopod
are dorsal and
ventral. In this species the dorsal valve is smaller and underneath,
the ventral valve is larger, has the opening for the pedicle, and is on
top so the animal normally lives "upside-down". The hinge is the
end of the animal and the opening is anterior.
Range: Alaska to Baja
Range: It is found in the low
intertidal zone but is more commonly subtidal to at least a depth of
m in clean, quiet water.
This species, when found,
is usually attached to undersides or protected surfaces of large rocks.
History: The animal
is solitary. When it reproduces (in winter), the fertilized
develop into a characteristic 3-lobed and ciliated planktonic larva
like a trochophore. The larva does not feed
The larva attaches and then develops into an adult. Predators
this species include crabs, which chip off parts of the margin of the
to reach the soft parts, and the seastars Evasterias
troschelii and Orthasterias
koehleri. The lampshell may survive crab attacks
and many show
asymmetrical shell growth from repairs that have been made.
and Hanby, 2005
et al., 1980
and O'Clair, 1998
This species is often encrusted with coralline algae. Photo
Dave Cowles, July 2000
This individual has unusually pronounced growth lines. Shell
found dead at 12 m depth near many live individuals off the Cone
by Jim Ramaglia, and provided by Andrew Rice. Photo by Dave
This view of the under (dorsal) side of the animal shows the dorsal
valve. At the top of the photo is the ventral (upper) valve with the
from which the pedicle exits at the posterior end of the valve. The
pedicle attaches to a rock, and the side shown here would be oriented
in life. Note that the opening for the pedicle is at the very posterior
end of the valve and the posterior end is not pointed. Photo of a 4.2
individual by Dave Cowles, August 2020.
This is the normal orientation of the animal in life. The dorsal valve
is down, and the larger ventral valve is up. The fleshy pedicle
through the opening in the ventral valve seen on the right and attaches
to a rock. Anterior is to the left and posterior to the right. Note
the ventral valve, which is on top and thus would receive more light,
encrusted with coralline algae in this photo while the corsal valve on
the bottom is not. Photo of the same individual as shown for the dorsal
valve above by Dave Cowles, August 2020.
This photo shows the hinge articulation. The two valves are
so that they cannot be opened more than in the picture without
The fragile brachidium has already broken off in this individual. Photo
by Dave Cowles
The set of brachial arms (brachidium) is a skeletal element which
It is very fragile and usually breaks free when the animal dies or is
This photo shows a mostly intact brachidium. Photo by Dave Cowles, July
Authors and Editors of Page:
Anna Dyer (2002): Created original page
Edited by Hans Helmstetler 11-2002; Dave Cowles 2005-