Seanet High Intertidal

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Littorina keenae (Phillippi, 1847) Rosewater, 1978
Phylum Mollusca, Cl. Gastropoda, Subcl. Orthogastropoda, Superorder Caenogastropoda, O.Sorbeoconcha, F. Littorinidae

Periwinkle; shell smooth to 23 mm, brown to black with white patches & fine spiral lines (often eroded); aperture longer than half shell length, inside brown with white inward-curving stripe at base (arrow); smooth flattened parietal area adjacent to posterior end of aperture (arrow); tan columella wide & polished.

Abundant on bare rock in high intertidal zone, exposed & protected outer coast; browses on microalgae.

Geo Range: Coos Bay, Oregon to central Baja
Synonyms: Littorina planaxis
Similar species: Littorina plena & L. scutulata are smaller; both lack wide columella & smooth patch on parietal area.  Must examine reproductive structures to confirm identification.