Sand dollars are flattened sea urchins, related to sea stars and sea cucumbers. Many recognize their bleached, white, disc-shaped skeletons, called “tests,” often found washed ashore. These are remnants of living creatures that inhabit sandy ocean floors. Understanding a live sand dollar’s characteristics helps distinguish between a natural souvenir and a living organism.
Identifying a Living Sand Dollar
Live sand dollars display physical and behavioral traits that differentiate them from dried counterparts. Their color is a primary indicator; living specimens are dark, ranging from brown, gray, or reddish to purplish hues. This coloration comes from thousands of tiny, velvety spines covering their surface. These flexible spines constantly move to aid locomotion, burrowing, and feeding. If gently placed in your hand, you might observe subtle spine movement.
Tube feet and cilia on the sand dollar’s underside are another sign of life. These hair-like structures facilitate food particle movement towards the central mouth and assist respiration. Gently touching the underside may reveal a slight stickiness or tiny feet moving. Live sand dollars also feel heavier than dead ones due to their water content; dead tests are lightweight and brittle. Occasionally, a living sand dollar may release a harmless yellowish substance called echinochrome, which can stain the skin.
Natural Habitat of Sand Dollars
Sand dollars thrive in marine environments, inhabiting sandy or muddy bottoms in shallow coastal waters. They are often found in large, dense colonies, with hundreds of individuals occupying a single square yard. They prefer areas with calm to moderate water movement, where they can partially bury themselves in the sediment. Their flattened bodies allow them to burrow, providing protection from strong currents and predators.
Sand dollars are found globally, remaining submerged. Live sand dollars are rarely found washed up on beaches, as they cannot survive long out of water. The white, smooth “shells” commonly encountered on the shore are skeletons of sand dollars that have died, been cleaned by the ocean, and bleached by the sun.
Responsible Interaction with Sand Dollars
Responsible interaction with live sand dollars is important for their conservation. Collecting live sand dollars is illegal in many coastal areas. These organisms play a role in the marine ecosystem, contributing to nutrient cycling and serving as a food source for other marine life. Removing them can disrupt the delicate balance of their habitat.
If a live sand dollar is found stranded on the beach, gently return it to the water. The ideal location is where it was found or in slightly deeper, calmer water nearby. Sand dollars cannot survive for long periods out of their aquatic environment. Only bleached, spineless tests should be collected as souvenirs, allowing living creatures to remain in their natural habitat.