Red Sea Urchin 7681164010 O
27Identifcation number on The Map®

Red Sea Urchin

Strongylocentrotus franciscanus

Red Sea UrchinDave Rudie


  • This large sea urchin has sharp spines that are about 1/2 as long as the diameter of the chest
  • Color ranges from red, red brown, to dark purple
  • Diameter to about 10 inches
  • The animals have a mouth with special jaws (Aristotle’s Lantern) located on the bottom (oral) surface
  • During larval development, urchins use bands of cilia to capture food from the water column


  • Northern Japan and Alaska to Isla Cedros, Baja California


  • Lives on rocks; from low intertidal to about 300 feet in depth


  • Their preferred diet is seaweeds, kelp and algae, which they scrape off and tear up from the sea floor

Interesting Facts

  • Sea Urchins are often found living in clumps from five to ten
  • They have the ability to regenerate lost spines
  • Lifespan often exceeds 30 years, and scientists have found some specimens to be over 200 years old
  • Spawning peaks between June and September
  • Eggs are fertilized externally while they float in the ocean, and planktonic larvae remain in the water column for about a month before settling on the bottom of the sea floor, where they undergo metamorphosis into juvenile urchins
  •  Juveniles use chemical cues to locate adults
  •  Although juveniles are found almost exclusively under aggregated adults, the adults and juveniles are not directly related
  •  Red Sea Urchins can effectively reproduce even if they are incredibly old
  •  This urchin supports a very large commercial fishery on the Pacific coast of North America. Divers collect them for their roe