Monday, August 17, 2009
One of the most popular and sought after seashell is the sand dollar sea shell (echinarachnius parma). When they reach us at the beach, they are typically bleached white from the sun, round in shape and show no signs of ever having once been alive. So, what are sand dollars like when they're alive?
When alive, sand dollars are covered with many tiny, maroon colored, hairlike spines. These spines work a lot like the legs of a centipede or spider and allow the sand dollar to move around the ocean floor as well as pick up food. The flower petal-like pattern on the sand dollar’s shell is actually 5 paired rows of pores. These pores are holes in the endoskeleton through which the podia, used like fish gills, project from the body to allow the sand dollar to "breathe". Like the sea star, sand dollars have their mouths on their stomachs. The spines around their mouth gather and push small microorganisms into their mouth. Sand dollars live in the intertidal zone (the area between high tide and low tide) in the ocean.
Sand dollars have few natural enemies due to their hard, protective shells and the precious little edible parts to them. One of their few known enemies is the thick-lipped, eelpout (also known as an ocean pout or zoarces americanus).
The best time to find sand dollar seashells is right after a big storm. The waves will have dredged up many of the dead, discarded shells from the ocean floor. If you are not concerned with preserving the shell for your collection, I would suggest breaking it open. You may find many hard, white loose pieces inside. These were the sand dollars teeth!