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Biology/Natural History: This species is less resistant to emersion than is P. granosimanus, but it is more tolerant of brackish water. Many occupy small, light shells which they cannot completely retract into. They will also abandon their shell more readily than do some other species, such as P. granosimanus (photo), sometimes even when they are berried (carrying eggs (photo). They seem to have definite shell preferences, but these may be different in different places. Favorites include Nucella lamellosa, Searlesia dira, Littorina spp, and Olivella biplicata shells. Diet is mainly detritus, though they will eat live prey opportunistically. It is known to feed on hatchlings of Nucella emarginata, which lay and attach their eggs in the low intertidal. Predators include sculpins. Females become ovigerous in late fall and carry a total of about 5 broods through spring and summer. Parasites include the parasitic barnacles Peltogaster paguri and Peltogastrella gracilis and the bopyrid isopod Pseudione giardi.