Key:  Family Littorinidae

Phylum Mollusca
 Class Gastropoda
  Subclass Prosobranchia
   Order Mesogastropoda
    Suborder Taenioglossa

Taken primarily from  Kozloff, 1987, 1996 p. 209 (Copyright 1987, 1996, University of Washington Press.  Used in this web page by permission of University of Washington Press)

Note:  Since the writing of Kozloff's key, Family Lacunidae has been included in Family Littorinidae as Subfamily Lacuninae
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1a  Diameter almost equal to the height; often with rather prominent spiral ridges (height up to about 2 cm; common, but mostly north of Oregon; primarily on rocky shores, but also on rocks, wood, and debris in bays and salt marshes Littorina sitkana
1b Height of shell decidedly greater than the diameter; without obvious spiral ridges 2
2a Spire generally consisting of 3 whorls; usually with a white band inside the lower portion of the aperture, near the columella (color, except when the shell is eroded, usually brown or nearly olive, with irregular lighter mottling; not likely to be found north of Oregon) Littorina keenae
2b Spire generally consisting of 4 whorls; without a white band inside the aperture 3
3a Shell thick (typical for Littorina); without an umbilicus; height to 1.5 cm; color usually dark brown, purple, or black, often with a checkerboard pattern of whitish areas or white streaks.  Common on rocky shores and also found on rocks in bays.  [Littorina plena, known to occur in Oregon and California, cannot be distinguished from L. scutulata based on these characters] Littorina scutulata
3b Shell thinner than typical for Littorina; with an umbilicus that is partly covered by the flangelike inner lip of the aperture; height to 8 mm; color brown (there are generally 2 or 3 wide, spiral bands of dark brown separated by narrow bands of lighter brown); restricted to salt marshes, where it is found on vegetation (Algamorda subrotundata in key) Littorina subrotundata

Taxonomic Levels Represented in This Key:

  Littorina scutulata
  Littorina sitkana
  Littorina subrotundata

Page created by Dave Cowles, 2004
Edited by: Dave Cowles 2005, 2006