Sea Urchin

photo by Kirt L. Onthank CC BY

Sea Urchin look like round, spiny balls (usually 1-4 in across). They can be found in oceans around the world but are much less common in the cold polar areas. They have hard shells and use their tube feet to crawl along the sea bed. Their spines help protect them from predators but also help them to move about and to trap food particles.

Sea Urchin have a mouth on the underside of their body with 5 teeth they can use to grab, scrape, pull, and tear. Sea Urchin eat both plant and animal matter, such as seaweed, algae, and dead animals.

Sea Urchin are closely related to Starfish and Sand Dollar that also have radially symmetrical bodies.

There are many different species of Sea Urchin. Red Urchin have long spines and can live more than 200 years. Green Urchin have very fine, short spines and can be found in calm areas without too much wave activity. Purple Urchin prefer areas with a strong surf and are common in the Atlantic Ocean.

Did you know? Sea Urchin breathe through their tube feet.

See Also: Barnacle, Blue Mussel, Clam, Crab, Harbor Seal, River Otter, Sand Dollar, Sea Anemone, Sea Lion, Sea Otter, Starfish