GEORGETTE DOUWMA / Purple sea urchins {Strongylocentrotus purpuratus} in tide pool at low tide, Tongue Point, Washington, USA.

Norbert Wu / Wolf Eel (Anarrhichthys ocellatus) feeds on Crabs and Purple Sea Urchins (Strongylocentrotus purpuratus) six feet long, Monterey, California

Norbert Wu / Purple Sea Urchin (Strongylocentrotus purpuratus) group feeds on algae, southern California

Norbert Wu / Bat Star (Asterina miniata) surrounded by Purple Sea Urchins (Strongylocentrotus purpuratus) in Urchin Barrens, San Diego, California

Norbert Wu / Garibaldi (Hypsypops rubicundus) males defend algal nest by removing grazing Purple Sea Urchin (Strongylocentrotus purpuratus), southern California

Norbert Wu / Purple Sea Urchin (Strongylocentrotus purpuratus) group feeding on Kelp (Macrocystis pyrifera) plants at base, killing entire 100 foot plant, San Diego, California

Norbert Wu / Garibaldi (Hypsypops rubicundus) male removes algae grazing Purple Sea Urchin (Strongylocentrotus purpuratus) from algal nest, southern California

Norbert Wu / Purple Sea Urchin (Strongylocentrotus purpuratus) barrens, population explosion destroys once lush Kelp forest, southern California

Jeff Rotman / Colony of Purple sea urchin {Strongylocentrotus purpuratus} feeding on kelp, California, USA

Jeff Rotman / Purple sea urchin underside showing mouth. Pacific Channel islands, California

Jeff Rotman / Purple sea urchins {Strongylocentrotus purpuratus} feeding on kelp, Pacific, California, USA

Ralph Pace / Purple Sea Urchin (Strongylocentrotus purpuratus) group creating urchin barren by feeding on kelp, Carmel, California