Periwinkle The common periwinkle or winkle (Littorina littorea) is a species of small edible whelk or sea snail, a marine gastropod mollusk that has gills and an operculum, and is classified within the family Littorinidae, the periwinkles. This is a robust intertidal species with a dark and sometimes banded shell.
The common periwinkle is one of the most abundant snail species in the world with an estimated population of about 3 x 10 11 individuals, occupying 5-20% of rocky shores within its geographical range. A closely related species, Littorina saxatilis, was previously considered a subspecies of Littorina littorea.
The common periwinkle is found in North America, Europe, Turkey, and North Africa. In Britain, it has a very limited range around South Wales and southwest England from Cornwall to Dorset. It also occurs around the rest of the coast of Europe, including northern Spain and Portugal. In Europe, it is found from the low tide line to depths of 50 m. It lives mainly on rocky shores and in crevices where it feeds on algae and other organisms by grazing, often using a radula tooth rake to scrape off food.
The common periwinkle is preyed upon by numerous animals: sea stars such as Pisaster ochraceus and the leather star (Dermasterias imbricata); fish such as the three-spined stickleback (Gasterosteus aculeatus) and shanny (Pikeblennius spp.), cuttlefish; cormorants; gulls; terns; shore crabs Carcinus maenas and Littorina saxatilis; the starlet sea anemone (Isanthidae); and some nudibranchs. In Great Britain, it is known to be preyed upon by the whelk Nucella lapillus. The common periwinkle is itself a predator on barnacles, mussels (Mytilus spp.), and other small mollusks such as the dog whelk (Nucella lapillus).
The common periwinkle is an important member of intertidal communities in northern Europe and North America where it occupies the same ecological niche as Littorina littorea, a closely related species that is much more widespread in northern Europe. The two species are difficult to tell apart, but the common periwinkle grows to a larger size (max. length 80 mm) and lives mainly in crevices rather than under boulders like Littorina littorea.
The common periwinkle feeds primarily on algae but also consumes a variety of foods, including invertebrates such as mussels and barnacles, detritus, microscopic particles, and carrion. A new home is made by the periwinkle by creating a U-shaped gap in a boulder, then by cementing the gap with calcareous material