Grazes on microalgae and coralline algae. Predators include shore crabs, clingfish, the seastars Leptasterias hexactis
, Pisaster ochraceous
, Evasterias troschelii, and Pycnopodia helianthoides. The limpet crawls rapidly away and may slowly shake its shell from side to side when it encounters one of its predator seastars. Near Rosario this limpet is eaten by the black oystercatcher but to a lesser extent than is Tectura persona
, perhaps because its flat shape makes it difficult to dislodge by pecking. It is said to move up and down with the tide, and I have observed that it seems to be more out in the open at night than during the day. The limpet does not seem to home to a particular place on the rock. When submerged they move upward, but more slowly if there is light coming from above. In some places, the smaller limpets are found higher in the intertidal than are larger individuals. Respiration is through the gill and mantle, with the mantle being especially important when the animal is exposed at low tide. The radula of this species is unusual. It is twice as long as the shell (although only the front end is used). The posterior end of the radula responds weakly to a magnetic field. Juvenile amphipods Hyale grandicornis
are often found in the pallial groove of this species. Sexually mature and "ripe" females have a purple spot in the center of the foot, while "ripe" males have a white line to the left of the middle of the foot. Spawning occurs from April to June in Washington.