Common Periwinkle (also known as the Littorine or Edible Periwinkle)
Phylum: Mollusca, Class: Gastropoda, Order: Littorinimorpha, Family: Littorinidae, Genus: Littorina, Species: Littorina littorea · Littorinidae (Periwinkle family) · Gastropod (snail/univalve), whole shell, spiral shape
Species
Littorina littorea
Shell Type
Gastropod (snail/univalve), whole shell, spiral shape
Family
Littorinidae (Periwinkle family)
Size
Approximately 0.4 inches (10 mm) in length, which is a juvenile specimen. Adults typically range from 0.5 to 1.2 inches.
Color & Pattern
Dark brown to blackish base color with faint, spiraling paler bands and streaks of white or cream. The coloration is natural and glossy with intact exterior surface.
Rarity
Very Common
Habitat
Intertidal zone, typically found on rocky shores, intertidal mudflats, and salt marshes attached to rocks, seaweed, or hard substrates. Marine species.
Geographic Range
Native to the northeastern Atlantic coasts of Europe, introduced and widely established along the northeastern and northwestern coasts of North America.
Description
A small, sturdy, conical shell featuring a moderately elevated spire consisting of about five to six convex whorls. The surface is smooth with faint growth lines and spiral striations. The aperture is rounded to oval with a sharp outer lip and a small columella.
Key Features
Small, robust conical shell with dark brown banding, a moderately acute spire, lack of an umbilicus, and a smooth, polished exterior surface when clean.
Collector Value
Low commercial or collector value due to extreme abundance, though commonly collected by beginner beachcombers and children.
Condition Notes
The shell appears to be in excellent, intact condition (Gem grade) with full color retention, no visible boring holes or major structural damage, and a sharp outer lip.
Interesting Facts
Littorina littorea is an invasive species in North America that was introduced from Europe in the 19th century. They are herbivorous grazers that feed on microalgae and can drastically alter rocky shore ecosystems by controlling algal growth.
Ecological Role
Acts as a primary herbivorous grazer controlling macroalgal and microalgal populations on intertidal rocks, serving as a prey item for shorebirds, crabs, and fish.
Similar Species
Rough Periwinkle (Littorina saxatilis) and Smooth Periwinkle (Littorina obtusata). Littorina saxatilis has a rougher texture, while Littorina obtusata is broader and prefers fucoid algae.
Beach Finding Tips
Look along rocky shores, jetties, and tide pools during low tide, particularly clinging to seaweed or nestled in rock crevices.