Sealife guideThe red sea urchinMesocentrotus franciscanus

Last updated on 09/30/2025 at 11:08 PM
Taxonomy
Description
The red sea urchin is the largest sea urchin species and can reach a diameter of about 7 inches in the largest specimens. Its body is dark red to black in color with large, lighter red spines.
The red sea urchin (Mesocentrotus franciscanus)
The red sea urchin (Mesocentrotus franciscanus) © | Dreamstime.com
Geographic range
The red sea urchin is found on the eastern side of the Pacific ocean, along the west coast of North America down to the tip of Baja California, Mexico.
Habitat
The red sea urchin mainly lives in the rocky parts of the shoreline, also called the intertidal zone and down to depths of about 525 feet.
Diet
The red sea urchin is an herbivore and feeds mainly on kelp, which is why it is often found in kelp forests.
The red sea urchin (Mesocentrotus franciscanus)
The red sea urchin (Mesocentrotus franciscanus) © | Dreamstime.com
Around San Diego, the main predators of the red sea urchin are the California spiny lobster and the California sheephead, while north of Point Conception the main predator is the sea otter.
Reproduction
After the eggs are released into the seawater and fertilized, larvae hatch and drift freely before settling on the seafloor and developing into young juvenile sea urchins.
Did you know ?
By feeding on giant kelp, the red sea urchin plays an important role in the development of giant kelp forests and in shaping the structure of the entire ecosystem.
The red sea urchin (Mesocentrotus franciscanus)
The red sea urchin (Mesocentrotus franciscanus) © | Dreamstime.com
Discover also
Biscuit sea star (Peltaster placenta)
Biscuit sea star
(Peltaster placenta)
Golden crinoid (Davidaster rubiginosus)
Golden crinoid
(Davidaster rubiginosus)
Hatpin sea urchin (Centrostephanus longispinus)
Hatpin sea urchin
(Centrostephanus longispinus)
Long-spined sea urchin (Diadema antillarum)
Long-spined sea urchin
(Diadema antillarum)
Mosaic sea star (Plectaster decanus)
Mosaic sea star
(Plectaster decanus)
Red striped sea cucumber (Thelenota rubralineata)
Red striped sea cucumber
(Thelenota rubralineata)
Sea Apple (Pseudocolochirus violaceus)
Sea Apple
(Pseudocolochirus violaceus)
West Indian sea egg (Tripneustes ventricosus)
West Indian sea egg
(Tripneustes ventricosus)
The marine species from eastern Pacific ocean
California sheephead (Bodianus pulcher)
California sheephead
(Bodianus pulcher)
Garibaldi (Hypsypops rubicundus)
Garibaldi
(Hypsypops rubicundus)
Giant kelp (Macrocystis pyrifera)
Giant kelp
(Macrocystis pyrifera)
Gorgona guitarfish (Pseudobatos prahli)
Gorgona guitarfish
(Pseudobatos prahli)
Leopard shark (Triakis semifasciata)
Leopard shark
(Triakis semifasciata)
Mexican hogfish (Bodianus diplotaenia)
Mexican hogfish
(Bodianus diplotaenia)
Mosshead warbonnet (Chirolophis nugator)
Mosshead warbonnet
(Chirolophis nugator)
Sheep crab (Loxorhynchus grandis)
Sheep crab
(Loxorhynchus grandis)

Our latestUpdates

Disney Hollywood Studios, from Star Wars to Toy Story
Friday, November 28th 2025
Disney Hollywood Studios, from Star Wars to Toy Story
Dive into the magical world of Disney's Hollywood Studios: Star Wars and Toy Story attractions and shows for the whole family.
Tenerife island
Wednesday, November 19th 2025
Tenerife island
Tenerife, the largest of the Canary islands, is a volcanic gem in the Atlantic ocean. It boasts an incredible variety of landscapes, from golden or black sand beaches to the subtropical forests of the Anaga mountains and the majestic Teide volcano, Spain's highest peak. With its picturesque villages, rich local culture and countless outdoor activities, Tenerife is a perfect destination for every type of traveler.
Batz island
Saturday, November 15th 2025
Batz island
Located in the English Channel off the northern coast of Brittany, just a few kilometers from the town of Roscoff, Batz island is a true little haven of peace where you can enjoy its wild landscapes, unspoiled beaches and historical heritage.
Photo of the Day
Requin cuivre (Carcharhinus brachyurus)
Requin cuivre
(Carcharhinus brachyurus)