Sand dollars are intriguing marine creatures often found along coastlines. Many beachgoers encounter the familiar white, disc-shaped structures and assume they are just pretty souvenirs. However, these fascinating animals are alive and play a role in their marine habitats before becoming the bleached, rigid forms collected on beaches. Understanding the distinctions between a living sand dollar and its skeletal remains helps in appreciating these organisms and practicing responsible beachcombing.
Identifying a Living Sand Dollar
A living sand dollar looks quite different from the white “shell” many people recognize. They are covered in a dense layer of tiny, flexible spines, giving them a velvety or fuzzy appearance. These spines are modified tube feet, used for movement, burrowing, and feeding. If you gently hold a live sand dollar, you might observe these minute spines wiggling or slowly moving, indicating the creature is active.
The color of a living sand dollar is another clear indicator; they are not white. Their natural coloration ranges from shades of brown to purplish, reddish, or dark gray, providing camouflage. If you encounter a sand dollar with these darker hues and a velvety texture, it is likely alive. Additionally, some living sand dollars may release a harmless yellowish substance called echinochrome when handled, which can temporarily stain your skin.
The Journey to a Beach Souvenir
The familiar white, smooth sand dollar found on beaches is not the living animal, but its “test” or skeleton. After a sand dollar dies, its soft tissues decompose, and the tiny spines fall off. This leaves behind the internal, hard, disc-shaped structure composed of calcium carbonate.
The skeletal remains are then tossed around by waves and currents. Exposure to sunlight and the abrasive action of sand and water gradually bleaches the test, turning it from its original dark color to the characteristic white or off-white seen on shore. This bleached, spineless form is what many people collect as a beach souvenir, often recognizable by the distinctive five-petal or star-shaped pattern on its surface.
Responsible Beachcombing
When exploring the beach, distinguish between living and deceased sand dollars to protect marine ecosystems. If you find a sand dollar exhibiting signs of life—such as its natural dark color, velvety spines, movement, or echinochrome release—gently return it to the water. Live sand dollars cannot survive long out of water, typically only a few minutes, and removing them can be detrimental. In many locations, collecting live sand dollars is illegal and can result in fines.
Conversely, if a sand dollar is white, smooth, and lacks spines or signs of movement, it is considered dead and can be collected as a souvenir. These empty tests are natural remnants of the marine environment and pose no harm to the ecosystem when collected responsibly. Sand dollars contribute to their habitat by filtering detritus and serving as a food source for other marine animals, underscoring the importance of leaving living specimens undisturbed.