Common Periwinkle (littorina littorea):
The Periwinkle is a small gastropod that lives in the inter-tidal zones of most North American coastal beaches. They belong to a larger classification of sea-snails called Littorinidae, and are a significant food source for many animals. They were introduced to this area in the mid-1900’s through human activity, and have experienced a population boom over the last 100 years. There is concern over the extent of damage they have caused to other competitive gastropod species, and many biologists fear that they could cause an imbalance in our native coastal ecosystems. They can be identified by their small size and distinctive shell shape, which is often pigmented with purple, grey, and blue. They are omnivorous, but primarily graze algae growing on the surface of rocks and boulders at the water line. They are motile and will travel significant distances in search of water or food. Historical evidence suggests that Europeans used periwinkles for food and clothing dye as early as 7500 B.C. !.
Common Periwinkle