Carinacea Kroh & Smith 2010

Scleractinia, Porifera

Poriferous zone Stomopneustes variolaris test

Aboral (top) surface of purple urchin showing anus surrounded by spines, pinchers, and tube feet.

Closeup showing the urchin's chewing apparatus, 'Aristotle's lantern.'

Skeleton of purple urchin shows convex points of attachment of spines and openings for branches of the water vascular system that serve the tube feet.

Depth 24 m. For about two years, purple urchins denuded a localized patch of sea floor at moderate depth. We do not know why the sea otter did not prevent this localized catastrophe.

Porifera, Nudibranch?

The purple sea urchin, Strongylocentrotus purpuratus, lives along the eastern edge of the Pacific Ocean.

purple sea urchin with coralline algae