Biology/Natural History: This species is more common subtidally in the Pacific Northwest than farther south in areas like Monterey Bay. On the east coast of North America, the migration behavior of its larvae serves to make it especially abundant in estuaries. The earliest naupliar stages are found high in the water column and so move outward in the estuary with the fresh water outflow. Later stages swim deeper and are carried back into the estuary, where they settle. In Monterey Bay this species settles sporadically almost year round. It can grow to 2 cm diameter in 1 year. Usually they grow wide, but when crowded can grow tall and narrow. Predators include seastars such as Evasterias troschelii.