Common periwinkle, also known as the 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 10 to 15 millimeters in length, which is small and juvenile or typical for a younger specimen. Adult periwinkles typically range from 20 to 40 millimeters.
Color & Pattern
Pale greenish-grey to light greyish-white base color. The colors appear somewhat weathered and sun-bleached, typical of specimens found high in the intertidal zone.
Rarity
Very Common
Habitat
Intertidal zone, typically found on rocky shores, intertidal mudflats, and salt marshes, clinging to rocks, algae, and seaweed. It is a marine and brackish water species.
Geographic Range
Native to the rocky shores of the northeastern Atlantic Ocean, including northern Europe, and introduced to the northeastern and northwestern coasts of North America.
Description
A small, robust, turbinate or conical shell with a smooth to finely striated surface. It features a pointed spire consisting of several tight-coiling whorls, a relatively small aperture, and a solid outer lip. The simple yet durable architecture allows it to withstand heavy wave action on rocky coastlines.
Key Features
Small, pointed spire, turbinate shape, dark or greyish-green banded color variations (when fresh), and lack of a siphonal canal. The columella is smooth and the outer lip is simple and sharp.
Collector Value
Low collectible value as it is extremely common and widespread. It is typically collected by beginners or beachcombers rather than advanced shell collectors, holding little to no monetary value.
Condition Notes
Fair condition. The shell shows signs of sun-bleaching with a faded, pale green-grey hue, and minor surface wear around the apex and body whorl, but remains fully intact with no major fractures.
Interesting Facts
Littorina littorea is a well-known intertidal grazer that feeds on microalgae and macroalgae, effectively controlling algae populations on rocky shores. It was introduced to North America from Europe and is commonly consumed as seafood in various cultures.
Ecological Role
Acts as an important primary consumer and herbivore, grazing on algal films and preventing algae from overgrowing rocky substrates, thereby maintaining the balance of the intertidal ecosystem.
Similar Species
Flat periwinkle (Littorina obtusata) and rough periwinkle (Littorina saxatilis). Littorina obtusata has a much flatter, broader spire, while Littorina saxatilis tends to have rougher, more pronounced sculptural ridges.
Beach Finding Tips
Look along rocky intertidal zones during low tide. They are often found clinging to rocks, hidden in crevices, or among clumps of seaweed and rock pools.