Floris van Breugel / Giant Red Sea Urchins (Strongylocentrotus franciscanus) Purple sea urchins (Strongylocentrotus purpuratus) and Sea Anenomes (Anthopleura) underwater, in tide pools along Californian coastline, USA.

Fred Bavendam / Purple Sea Urchin (Strongylocentrotus purpuratus) and Red Sea Urchin (Strongylocentrotus franciscanus) group, Channel Islands, California

Flip Nicklin / Purple Sea Urchin (Strongylocentrotus purpuratus) with tube feet extended into water to feed, California

Georgette Douwma / Purple sea urchins, California USA

Olga Kamenskaya / Purple sea urchin (Strongylocentrotus purpuratus) off the coast of Svalbard, Norway. September.

Richard Herrmann / Red Sea Urchin (Strongylocentrotus franciscanus) and Purple Sea Urchin (Strongylocentrotus purpuratus) feeding on Southern Sea Palm (Eisenia arborea) creating urchin barren, Santa Cruz Island, Channel...

Franco Banfi / Purple sea urchin (Strongylocentrotus purpuratus) Little Strytan dive site, Eyjafjordur nearby to Akureyri, northern Iceland, North Atlantic Ocean.

Norbert Wu / Purple Sea Urchin (Strongylocentrotus purpuratus) group feeding on Giant Kelp (Macrocystis pyrifera), creating urchin barren, California

Norbert Wu / Brittle Star (Ophiothrix spiculata) group and Purple Sea Urchins (Strongylocentrotus purpuratus), California

Norbert Wu / Purple Sea Urchin (Strongylocentrotus purpuratus), Vancouver Island, British Columbia, Canada

Norbert Wu / Sunflower Sea Star (Pycnopodia helianthoides) and Purple Sea Urchin (Strongylocentrotus purpuratus) in feeding on Frilled Sea Anemones (Metridium senile), Vancouver Island, British Columbia, Canada

Jeff Rotman / Purple Sea Urchins (Strongylocentratus purpuratus) colony feeding on kelp bases. Channel Islands, USA, Pacific Ocean.

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

Jaymi Heimbuch / Western Gull (Larus occidentalis) feeding on Purple Sea Urchin (Strongylocentrotus purpuratus) prey, Yaquina Head Outstanding Natural Area, Newport, Oregon

Richard Herrmann / Purple Sea Urchin (Strongylocentrotus purpuratus) and Brittle Stars (Ophiothrix spiculata), Santa Cruz Island, Channel Islands, California

Jeff Rotman / Purple sea urchin {Strongylocentrotus purpuratus} Channel Is, California, USA

Russell Laman / California sea lions (Zalophus californianus) swimming over rock covered in Bat stars (Patiria miniata) and Pacific purple sea urchins (Strongylocentrotus purpuratus) near the Monterey Coast Guard Pie...

Russell Laman / Giant spined star (Pisaster giganteus) on a rock alongside Pacific purple sea urchins (Strongylocentrotus purpuratus) underneath a Giant kelp (Macrocystis pyrifera) forest off the coast of Monterey, C...

Russell Laman / Pacific purple sea urchins (Strongylocentrotus purpuratus) feeding on Giant kelp (Macrocystis pyrifera) on seabed, Monterey, California, USA, Pacific Ocean.

Russell Laman / Pacific purple sea urchins (Strongylocentrotus purpuratus) and Strawberry anemones (Actinia fragacea) covering rocks on seabed, Monterey, California, USA, Pacific Ocean.

Russell Laman / California sea lions (Zalophus californianus) swimming over rocks covered in Pacific purple sea urchins (Strongylocentrotus purpuratus) and Strawberry anemones (Actinia fragacea), Monterey, California...

Shane Gross / Purple sea urchins (Strongylocentrotus purpuratus) and Red sea urchins (Strongylocentrotus franciscanus) on seabed, Barkley Sound, Vancouver Island, British Columbia, Canada.