Lacuna (Epheria) variegata Carpenter, 1864 

Common name(s): Variegate lacuna, variable lacuna, variegated chink shell, chink shell
Synonyms: Lacuna variegata snail
Phylum Mollusca
Class Gastropoda
Subclass Prosobranchia
Order Mesogastropoda
Suborder Taenioglossa
Family Littorinidae
Subfamily Lacunidae
Lacuna variegata from eelgrass in Padilla Bay.  Length about 6 mm
(Photo by: Dave Cowles, July 2008)
Description:   Chink shells (Family Littorinidae subfamily Lacunidae) are small and shaped rather like periwinkles (Family Littorinidae) but they have a slitlike open umbilicus next to the columella (photo).  They have recently been made a subfamily of Family Littorinidae.  They have a raised spire and an operculum but have neither a siphonal notch nor an anal notch.  They are slightly longer than wide.  The interior of the shell may be shiny but is not pearly.  The columella has no folds or ridges.  Lacuna variegata has an aperture just over half the height of the shell (photo).  The shell is light tan with chevron-shaped brown markings.  It has no spiral lines.  The larger whorls may have slightly flattened shoulders.  The operculum is thin and horny.  Shell is fragile, and about 4 whorls.  Height to 1.6 cm (but not often over 7 mm here).  Lamb and Hanby state that the shell flares at the aperture.

How to Distinguish from Similar Species:   The species may look much like Littorina scutulata, but L. scutulata has no open umbilicus and is found in the high intertidal on rocks while this species is in the very low intertidal on eelgrass.  Several other local Lacuna have apertures 2/3 the height of the shell. L. vincta has a spiral white band and is found on rocky shores.

Geographical Range:  Prince William Sound, Alaska to southern California.  Unlikely to be found south of Washington State.

Depth Range:  Low intertidal

Habitat:  Mainly on eelgrass.

Biology/Natural History:  Feeds on diatoms on eelgrass. Lacuna species hybridize readily and can be hard to distinguish.  This species lays a small ring of eggs on eelgrass or kelp, in late spring/early summer around Rosario.  The ring is greenish as first but becomes yellow as the eggs mature.


 
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References:

Dichotomous Keys:
  Kozloff 1987, 1996
 
 
 

General References:

  Kozloff, 1993
  Lamb and Hanby, 2005
  O'Clair and O'Clair, 1998

Scientific Articles:

Web sites:

General Notes and Observations:  Locations, abundances, unusual behaviors:
 

These snails and their eggs are common on the eelgrass of  Padilla Bay.
 


This view shows both the operculum and the open umbilicus.  Note that the aperture is very close to or just over half the height of the shell.


Authors and Editors of Page:
Dave Cowles (2008):  Created original page
CSS coding for page developed by Jonathan Cowles (2007)