We saw these Periwinkles above the tide pools at La Jolla Cove near San Diego. Periwinkles are algae eaters. These snails scrape microscopic algae from the surface of the rock. In scraping off the algae, the snails sometimes remove tiny bits of the rock. Scientists have estimated that over 100 years Periwinkles may remove as much as two and a half inches of rock.
Periwinkles live high in the inter-tidal region.
Periwinkles depend on the spray from ocean waves to keep them from getting dehydrated, so these animals must live near the water. This picture shows four Top Snails in a tide pool near Point Loma in San Diego . Unlike the Periwinkles, these snails live underwater. Top Snails are slightly larger than Periwinkles. These snails were perhaps 1 inch across.