Purple Sea Urchin

The five bony teeth of the sea urchin were given to the original created kind to help it scrape algae (its food) from rocks. The sea urchin also uses its teeth to “carve” away a depression in the rock where it will then settle and grab hold. This feature provides this creature with food and protection.


  • The purple sea urchin’s color can vary from a deep reddish purple to a light purple.
  • The sea urchin has a globe-shaped body, sharp spines, and a hard test, or shell.
  • The young purple sea urchin is a shade of green.

Fun Facts

  • The Old English term “urchin” was the name for the spiny hedgehog. The sea urchin resembles a hedgehog in appearance, so it was called “sea urchin.”
  • The sea urchin does not have a brain.
  • The sea urchin’s spines can be used in locomotion, defense, and capture of prey.

CLASS: Echinoidea (heart urchins, sand dollars, and sea urchins)
ORDER: Echinoida
FAMILY: Strongylocentrotidae
GENUS/SPECIES: Strongylocentrotus purpuratus

Size: Average 3.5 in (9 cm)
Diet: Algae, plankton, and seaweed
Habitat: Shallow waters off North America’s Pacific coast from Alaska to Baja California