The purple sea urchin that lives in the west coast of the United States is an echinoderm with tube feet and long spines and a mouth with strong jaws. It’s a voracious herbivore that can have a devastating influence on its environment if not held in check by predation.
Stanford’s Virtual Sea Urchin website is series of interactive tutorials. Urchins have been used for decades to study fertilization because it’s easy to stimulate fertilization and early development. There are also units on predator/prey interactions and the impact of ocean acidification on sea urchins. http://virtualurchin.stanford.edu/index.html
This is natural history and conservation reading from the Monterey Bay Aquarium. http://www.montereybayaquarium.org/animal-guide/invertebrates/purple-sea...
This is “An Army of Sea Urchins Eating Kelp” from Planet Earth.