Beachcombers often encounter the delicate, disc-shaped remains of sand dollars, prompting curiosity about whether a found specimen is alive or merely a skeletal remnant. These marine creatures often wash ashore, leading many to wonder how to distinguish a living organism from a bleached shell. This article provides clear guidance on identifying the signs of life in a sand dollar, helping you understand when to observe and when to leave them undisturbed.
What Are Sand Dollars?
Sand dollars are flattened sea urchins, belonging to the class Echinoidea. They possess a rigid, disc-shaped endoskeleton, known as a test, often found on the beach. When alive, their body is covered in countless tiny, movable spines that give them a velvety texture.
These creatures inhabit sandy or muddy ocean floors in shallow coastal waters, often burrowing just beneath the surface. They function as filter feeders, using spines and tube feet to capture microscopic food particles from the water or sand. Their presence contributes to the health of benthic ecosystems by processing organic matter.
Signs of Life to Look For
A live sand dollar displays a distinct coloration, ranging from purplish-brown to reddish-brown or dark green, which helps them camouflage on the seafloor. The familiar white sand dollar found on beaches is the sun-bleached test of a deceased individual, having lost its epidermis and spines. Any dark coloration indicates a living specimen.
Live sand dollars are covered in countless short, velvety spines that give them a “fuzzy” appearance and texture. These spines are used for locomotion and feeding, and may show subtle, coordinated movements if gently placed in a shallow pool of seawater. A dead sand dollar is smooth and bare, as its spines detach and erode after death.
Movement is another key indicator, although it can be very slow. If a sand dollar is alive and placed in a calm, shallow body of water, it might slowly attempt to burrow into the sand using its spines and tube feet. This burrowing action, or a slight twitching of the spines, confirms its living state. Minimal handling is advised due to their delicate nature.
The location where a sand dollar is found also provides clues to its vitality. Live sand dollars almost always reside submerged in water, often partially buried in the substrate. They are rarely found washed high up onto the dry sand of a beach. Finding a sand dollar in the intertidal zone, especially if wet, increases the likelihood it may be alive.
Live sand dollars possess a fresh, mild oceanic scent, characteristic of healthy marine organisms. A recently deceased sand dollar, particularly one that has begun to decompose, may emit a strong, unpleasant odor. A bleached, long-dead test will have no discernible smell.
Ethical Collection and Conservation
Discovering a live sand dollar requires a responsible approach to ensure its well-being. If you encounter a sand dollar that exhibits signs of life, gently return it to the water where it was found, or to a deeper, calmer area if it appears stranded by the tide. Minimizing handling is important, as their delicate bodies can be easily damaged. Be aware that local regulations often prohibit or restrict the collection of live marine animals without specific permits.
If a sand dollar shows no signs of life—appearing white, smooth, and lacking spines—it is merely the empty test and can be collected ethically. To prepare a dead sand dollar for preservation, rinse it thoroughly with fresh water to remove any remaining organic material or sand. After rinsing, allow it to air dry completely in a shaded, well-ventilated area, to prevent any lingering odor or degradation.
Responsible interaction with marine life contributes significantly to the health and sustainability of ocean environments. Leaving live creatures undisturbed allows them to continue their ecological roles, supporting the delicate balance of coastal ecosystems. Understanding the signs of life in sand dollars empowers individuals to make informed decisions that promote marine conservation.