The rate of new shell acquisition by hermit crabs, P. longicarpus, was monitored daily in northeastern Gulf of Mexico salt marshes where crown conchs, Melongena corona, prey heavily upon marsh periwinkles, Littorina irrorata. Periwinkle shells, marked while housing live snails, appeared on P. longicarpus at daily rates ranging from 1 to > 20 for selected areas of approximately 60 m2 in 3 marshes. The maximum number (22.8) of new periwinkle shells appearing among P. longicarpus in the immediate area (300 m2) represented 16.5% of crabs present there each day.