Terebratalia transversa (Sowerby, 1846) 

Common Lampshell 

Synonyms: None
Phylum Brachiopoda
 Class Articulata
  Order Telotremata
Terebratalia transversa  photo taken at Rosario Marine Station
Photo by: Anna Dyer, 08/02/02
Description:  The valves grow up to 56 mm wide, broader than long.  It is smooth with prominent radial ribbing.  The concentric sculpturing may or may not be conspicuous.  The pedicle valve has a slightly elevated median ridge and a rounded notch at the margin opposite the pedicle.  The shell’s color may be gray, yellow or reddish.

How to Distinguish from Similar Species:  Distinguished by location, color, and that it is broader than long.

Geographical Range:  Alaska to Baja California.

Depth Range:  It is found in the low intertidal zone but is more commonly subtidal to at least a depth of 1,800 m in clean, quiet water.

Habitat:  This species is scarce, but when found, is usually attached to undersides or protected surfaces of large rocks.

Biology/Natural History:  The animal is solitary.  When it reproduces, the fertilized eggs develop into a characteristic, but nameless, larva.  The larva does not feed and is planktonic.  The larva attaches and then develops into an adult.  The main predators of this species appear to be crabs, which chip off parts of the margin of the shell to reach the soft part.  The lampshell may survive these attacks and many show asymmetrical shell growth from repairs that have been made.

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Dichotomous Keys:
  Kozloff ,1987, 1996

General References:
  Morris et al., 1980

Scientific Articles:

General Notes/Observations:

This species is often encrusted with coralline algae.  Photo by 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 Islands by Jim Ramaglia, and provided by Andrew Rice.
Photo by Dave Cowles, July 2005.

This photo shows the hinge articulation.  The two valves are interlocking so that they cannot be opened more than in the picture without breaking.
Photo by Dave Cowles

Authors and Editors of Page:
Anna Dyer (2002):  Created original page
Edited by Hans Helmstetler  11-2002; Dave Cowles 2005