Thatched Barnacles
Semibalanus cariosus

These barnacles are white to grayish in color. They are easily identified because along the side of their shell they have ridges that appear to be “thatched” these are actually spines. These barnacles are sometimes difficult to identify because they can grow in column like shapes when there is overcrowding. The main predator of the thatched barnacle is the purple sea star (Pisaster ochraceus). I found these barnacles at Cattle Point and Argyle Lagoon on San Juan Island and in Olympic National Park at Tongue Point in Salt Creek Recreation Center.











































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This webpage is part of the UWT Marine Ecology 2007 Class Project