Kelp
Kelps are large brown algae seaweeds that make up the order Laminariales. There are about 30 different genera.
Pterygophora californica
"P. californica" grows in underwater kelp forests with other brown algae including the annual species, bull kelp ("Nereocystis luetkeana") and giant kelp ("Macrocystis pyrifera"). Brown seaweeds are photosynthetic organisms and their growth is mainly restricted by the availability of light. Various algae try to get a head start by attaching themselves to "P. californica" well above the ocean floor. These include red algae (Rhodophyte spp.), bull kelp ("Nereocystis luetkeana") and sea belt ("Saccharina latissima"). The most common cause of death of "P. californica" is being torn from the rocks during storms. This is made more likely by the drag caused by the epiphyte burden. "P. californica" and other Laminariales attempt to reduce their epiphytic load by periodically sloughing off their surface layers and by the production of "antifouling" substances such as phenols in their tissues.