Southern California Snails Southern California Snails . Periwinkles are small, stocky snails that live high in the inter-tidal region of the California coast. 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.