If you've ever taken a stroll along a sandy shoreline, you've probably discovered one of the most highly prized treasures to be washed up on the beach by the pounding surf: a sand dollar. Whether you're planning a trip to a sun-kissed seashore and want to know what to look for well in advance or you're simply intrigued by these unique organisms and want to soak up all the information about sand dollars you can, the following sand dollar facts are sure to come in handy the next time you encounter one of these creatures on your favorite stretch of sand.
What are sand dollars?
Coveted by shell seekers of all ages who sift through cockles and periwinkles, whelks and augers in search of the perfect souvenir from the sea, sand dollars are flat, round echinoderms-spiny-skinned creatures that live on the salty sea floor-that can be found in oceans throughout the world. Sand dollars are characterized by a purplish-colored coating of spines when they are alive in the sea and contain five sets of pores which are arranged into a pattern that resembles the petals surrounding a flower.
Once a sand dollar has died and washes up on the shoreline, it no longer has its covering of tiny spines and typically becomes bleached by the sun's rays, transforming it into a white-colored disk that bares little resembles to its living counterparts. Sand dollars are most closely related to creatures such as sea lilies, sea cucumbers, sea urchins and starfish. The Common Sand Dollar, or Echinarachnius parma, is a species that is native to the Northern Hemisphere.
What do sand dollars eat?
A sand dollar's diet consists primarily of organic particles that wind up in the sandy bottom of the ocean floor as well as plankton and algae. The tiny spines that form a coating on the outside of a sand dollar are covered in cilia, which move food to the creature's mouth opening in the center of its underside. Although they are commonly overlooked as food by most predators due to their relatively hard shell and few edible parts, some sea creatures-such as starfish, ocean pouts and skates-are capable of devouring them.
Where do sand dollars live?
Using their series of small spines to crawl through the sand, sand dollars are most often found on the ocean floor, generally amongst several other sand dollars. If you are searching for live sand dollars-which should be admired and appreciated in their living form but never removed from the sea-the best way to spot them is to comb the outer edge of the seashore after the tide has receded, exposing more of the ocean's sandy bottom. To collect the white-colored sand dollars that are no longer living in the seas, scour the shoreline after a strong storm, since rough surf tends to dredge up shells and sand dollars and deposits them along the beach.