Even the most seasoned beachcomber is excited and pleased to find a whole, intact sand dollar on the beach.
A common sand dollar is another name for a particular type of “flattened” sea urchin. The common sand dollar is found in the Northern Hemisphere in temperate and tropical waters.
On a good day at most North Carolina Beaches, you might find many sand dollars ranging in size from one to approximately four inches in diameter.
Sand dollars live on sandy or muddy flat areas of the ocean floor in shallow water near land. They often live in colonies. Female sand dollars release eggs that are fertilized externally.
Interestingly, the newly hatched larvae can clone themselves as a means of self-defense. If threatened, they can double their numbers by halving their size, thereby lessening the chance of being detected.
The larvae go through a few stages of development before forming an external skeleton that houses the animal’s internal organs.
The star on the skeleton was part of the food grooves that channel morsels to the mouth. The five-petal pattern around the star were sets of pores that extended to tube feet which allow for respiration.
IMPORTANT: If you find a sand dollar that is brownish and covered with short, dark, fur-like spines, the animal is alive and should not be removed from the beach.
A live sand dollar’s spines are covered with small hairs called “cilla.” By moving the cilla and spines, sand dollars are able to move across the sea beds in which they live. Mature sand dollars have few predators and can live up to ten years.
These sea creatures live in groups by the hundreds on the seafloor, partially burrowing themselves in the sand to remain in place as they catch food.
Finding Sand Dollars
The skeleton is called a “test” and it is this sun-bleached skeleton that beachcombers find on the shore. Beachcombers are most likely to find sand dollars in the morning at low tide, especially after a storm. When searching pay close attention to the area just below the high-tide line and look for round patches or depressions in the sand; these may turn out to be sand dollars on closer inspection.
The sun-bleached shells will be extremely fragile and will crumble or break easily.
To preserve the sand dollars that you bring home, rinse them several times in freshwater until the water runs clear, then soak them for 15 minutes in a 70% water, 30% bleach solution. Let it air dry completely.
When the sand dollars are dry, carefully paint them with a mixture that is half water and half white glue. The glue solution will make them less likely to break. You can also spray acrylic varnish or shellac to help protect the skeletons from chipping or breaking. Your beautiful sand dollars will last a long time if treated with care.
If you have trouble finding sand dollars on the beach, try taking a charter boat to sand dollar “hot spots”, small islands (really sand bars) out in the ocean that accumulate more shells than the shore, such as Sand Dollar Island, in North Carolina, Ocracoke Island in the Outer Banks, or Bear Island.