Sand dollars are flattened, burrowing sea urchins, which are marine invertebrates related to starfish and sea cucumbers. They possess a rigid skeleton, known as a test, composed of calcium carbonate plates arranged with a five-fold symmetry. This distinctive disc-like shape, often bleached white by the sun after the animal’s passing, is what beachcombers typically recognize. Finding one of these ocean treasures can be a rewarding experience for those exploring coastal areas. This article provides guidance on how to successfully locate sand dollars while ensuring responsible beachcombing practices.
Ideal Search Conditions and Locations
Sand dollars thrive in shallow coastal waters with sandy bottoms, often forming large colonies. They are less likely to be found on rough, rocky beaches, preferring calmer bays and areas where the sand is fine and soft. The most opportune time to search for sand dollars is during low tide, particularly after a strong storm. Lower tides expose more of the seabed where sand dollars reside, and storms can dislodge them from their sandy burrows, washing their tests ashore. Searching the tide line, where the ocean’s previous reach is evident, can often yield results. These conditions increase the likelihood of discovering intact specimens that have been naturally deposited onto the beach.
What to Look For
A sand dollar’s test is typically flat and disc-shaped, ranging from 5 to 10 centimeters (2 to 4 inches) in diameter. The most prominent feature is the five-petal pattern, or petaloid, on its top surface, which consists of five paired rows of pores. When found on the beach, these tests are usually white or grayish, bleached by the sun.
Effective searching involves scanning the sand along the low tide line and sifting through accumulations of shells and other debris. Sometimes, sand dollars may be partially buried, creating subtle mounds or slight irregularities on the sand surface. Looking for these small disturbances or areas where the sand has been recently disturbed can indicate a potential find. Gently sifting through the top layer of sand with your hands or a small tool can uncover buried treasures.
Distinguishing Live from Collected
For ethical beachcombing, differentiate between a live sand dollar and a dead, bleached test. Live sand dollars are typically dark brown, purple, or reddish in color, not white. Their entire body is covered in tiny, velvety spines, which are actually very small hairs (cilia) that allow them to move, burrow, and feed. If gently touched, a live sand dollar’s spines will show slight movement, and it may even feel fuzzy.
In contrast, a collected sand dollar is the dried, bleached skeleton, or “test,” of a deceased organism. These are white, brittle, and completely lack any spines or signs of movement. If you encounter a live sand dollar, it is essential to leave it undisturbed in its natural habitat, as they cannot survive for long out of water. Only dead, spineless, and white sand dollars should be collected.