Echinoidea - Sea Urchins

Though probably visible during normal low tides, exploring further into the crevices of the rocks of the tide pools, you are likely to find sea urchins. The living urchin is like a pin cushion covered with red, purple or green spines which are movable on a socket like base. These spines provide the creature with a protective coating as well as a means of transportation. Despite the spines, most California sea urchins can be picked up and held if done correctly.

Up to 3" wide, it digs holes n the rocks for protection against the waves. this burrowing is accomplished by a motion of the test - skeleton - and spines while the animals clings with its tube feet to the rock. Spines are quickly worn away by this abrasive contact but they are being constantly renewed by growth. The purple sea urchin primarily feeds on seaweed, which is chewed by the five toothed jaw known as Aristotle's Lantern, located on the underneath or "oral" side of the creature. Young purple sea urchins are green and due to their size require more thorough searching to be seen.

Purple Sea Urchin - Strongylocentrotus purpuratus

Red Sea Urchin - Strongylocentrotus franciscanus

The red sea urchin can also be found in these tide pools. These spines are longer than the purple sea variety and the red sea urchin does not show these same boring tendencies. If touched with a sharp object, the spines will immediately bend toward it as if an effort to keep it away from the test.

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