Coldwater Marine Aquatics recommends you keep these animals in 55F-60F water.
The common periwinkle or winkle, scientific name Littorina littorea, is a species of small sea snail, a marine gastropod mollusk that has gills and an operculum, and is classified within the family Littorinidae, the periwinkles. Littorina littorea is an omnivorous, grazing intertidal gastropod.The common periwinkle is primarily an algae grazer, but will feed on small invertebrates such as barnacle larvae. They use their radula to scrape algae from rocks, and, in the salt marsh community, pick up algae from the cord grass, or from the biofilm that covers the surface of mud in estuaries or bays.
This species is also found on the West Coast of the United States, from Washington (U.S. state) to California. Littorina littorea is now the most common marine snail along the North Atlantic coast. It has been shown to fundamentally change North Atlantic intertidal ecosystems via grazing activities, altering the distribution and abundance of algae on rocky shores and converting soft-sediment habitats to hard substrates, as well as competitively displacing some native species.The presence of this species has caused extensive damage due to interspecific competition with native intertidal gastropods.