These porcelain crabs are found in great numbers under most rocks in the intertidal and are characterized by their flattened bodies and large chelipeds. Five Petrolisthes species are found in the intertidal at different tidal heights and can be difficult to distinguish between. This specific species prefers rocky substrate and is intolerant of sand or silt, presumably due to their feeding mode. Porcelain crabs are filter feeders, sifting plankton and detritus from the water with fan-like mouthparts. (Oregon Estuarine Invertebrates)