Sand dollars, often mistaken for mere seashells, are fascinating marine animals belonging to the order Clypeasteroida, a type of flattened sea urchin. Understanding how to distinguish between a live and a dead sand dollar is important for beachcombers and nature enthusiasts. This distinction ensures ethical interaction with marine life and helps in responsibly collecting specimens.
Identifying a Live Sand Dollar
A live sand dollar appears significantly different from the bleached white disc often found on beaches. Their color typically ranges from dark shades of purple, brown, or greenish, due to a covering of tiny, velvety spines. These spines, which are hair-like cilia, are in constant motion, helping the sand dollar move, burrow, and feed. If gently held, one might observe subtle movement of these spines.
Live sand dollars are also more delicate than their dead counterparts. Sometimes, a live sand dollar may release a harmless yellow substance called echinochrome, which can temporarily stain skin, indicating life.
Identifying a Dead Sand Dollar
When a sand dollar dies, its body transforms into the familiar white skeleton, often collected as a souvenir. The distinctive dark colors fade, and the sand dollar becomes bleached, appearing stark white or gray due to sun exposure. The soft, velvety spines that cover a live specimen are completely absent, leaving a smooth, hard, and often brittle texture. The intricate, star-shaped pattern, known as petaloids, and sometimes small, round holes called lunules, become clearly visible on the clean, spine-free surface. These hardened remains are more durable and less prone to breakage.
Where to Find Them and What to Do Next
Live sand dollars inhabit shallow, calm ocean waters, often partially buried in sandy flats or seagrass beds. They can be spotted during low tide or by snorkeling, and in quiet waters, they may stand on one end, partially buried. If you encounter a live sand dollar, it is important to leave it undisturbed in its natural environment. Disturbing or removing live marine animals can harm them and may be illegal in many coastal regions.
Dead sand dollars are commonly found washed up on shorelines, particularly after storms or during periods of low tide. They are often mixed with shell debris and can be located by shuffling feet in shallow water or searching near the high-tide line. Once collected, it can be gently rinsed with fresh water to remove any sand or loose debris. For further cleaning and whitening, soak them in a diluted bleach solution (e.g., 1 part bleach to 4 parts water) for a short period, followed by thorough rinsing and sun-drying. This process helps preserve the sand dollar as a keepsake.