Photo 1: Red Sea Urchin at Low Tide.
Red Sea Urchin: Strongylocentrotus franciscanus
This sea urchin can grow quite large (up to 20 cm after 5 years). It is a herbivore, grazing on marine plants, especially kelp. In areas where its predators have been reduced, it has a tendency to over populate and then over graze causing vast barren areas called urchin barrens. The urchins are known for eating the holdfasts of kelp and setting the rest of the kelp adrift. It is preyed upon by sea otters, octopods, sea stars, crabs, and wolf eels.