by Philip Kiefer
There’s a war of attrition playing out on the coastlines of the San Francisco Bay that is in a ponderous class of its own. A tiny snail, called a rough periwinkle (Littorina saxatilis), might be pushing its native counterpart, the checkered periwinkle (Littorina scutulata), from the beaches it once called home. But no one is quite sure why, or even how quickly it’s spreading.
Adrielle Cailipan, a recent graduate of San Francisco State University, is spending her summer internship in the world of periwinkles with the West Coast Lab of the Smithsonian Environmental Research Center (SERC). She’s working not only to document the spread of the rough periwinkle, but also to understand what makes the invader so successful.










