How Can You Identify if a Sand Dollar is Alive Before Taking It from the Beach?

Walking along the shoreline and discovering a flawless, intact sand dollar is one of those small, indescribable joys in life that you may not fully appreciate until you've experienced it.

While many of us associate sand dollars with round, flat seashells, this is a misunderstanding of their true nature in the wild. Sand dollars are not shells at all, but living creatures!

Yes, a sand dollar is indeed alive at the start of its life. Over its typical 10-year lifespan, a sand dollar remains a living organism. It shares a family tree with other echinoderms, including sea cucumbers, sea stars (also known as starfish), and sea urchins.

As Jessica Brasher, the husbandry manager at the Ocean Institute in Dana Point, California, explained in 2019, "Much like their more famous sea star relatives, sand dollars exhibit five-part radial symmetry, meaning their body can be divided into five identical 'slices.'"

However, this symmetrical design isn't the reason sand dollars are classified under the echinoderm category that also includes sea urchins and sea cucumbers.

In fact, live sand dollars differ from their smoother, deceased counterparts in that they possess an endoskeleton covered by a layer of spiny skin, as noted by Leah Biery, former director of communications at Sanibel Sea School in Florida. In 2019, she explained via email, "Their skeleton, or test, is made of calcium carbonate bony plates called ossicles, which are bound together by connective tissue. They have no brain, just a simple nerve ring."

So, what makes a sand dollar truly alive? While most living creatures have limbs or some other obvious mode of movement, sand dollars travel in a more subtle way—through a water vascular system.

This system not only aids in the movement of sand dollars but also helps pump filtered seawater, which is essential for their feeding, Biery explained. The primary diet of sand dollars, whether young or old, consists of microscopic algae food particles that they scrape from hard surfaces with their teeth. Sand dollars also consume plankton and other small food drifting in the water.

Surprisingly, sand dollars are quite social. They prefer to rest flat on the sandy ocean floor, surrounded by other sand dollars, and avoid the turbulent waters caused by storms.

This behavior is especially crucial during the reproductive season, as being part of a large group of sand dollars increases the chances of successful reproduction.

As Jessica Brasher explained, "Sand dollars reproduce through spawning, where males and females release eggs and sperm into the water. If the eggs are fertilized, they develop into microscopic, free-floating larvae that bear little resemblance to their parents." These larvae undergo various stages of development before growing their test and settling on the ocean floor.

Is That Sand Dollar Alive or Dead?

Considering the complexity of a sand dollar's structure and life, is it okay to pick one up from the beach and bring it home as a souvenir? Well, that depends on a few factors.

As living creatures, sand dollars filter detritus and debris from the ocean floor, while also serving as a food source for many benthic (bottom-dwelling) predators such as sea stars, crabs, fish, and even the occasional octopus," Brasher explained.

"Even after they pass away, the shells of sand dollars continue to contribute calcium carbonate to our oceans. Since it can sometimes be hard to determine whether a sand dollar is still alive, it's best to leave it where you found it," she advised.

However, if you come across one and absolutely must take it home, make sure it is no longer alive and that its body is indeed dead. In most states, collecting a live sand dollar is illegal, but rules around gathering a deceased one can vary, so be sure to check for any notices on the beach or ask a local employee. In 2019, marine science educator John Rader from Sanibel Sea School shared these tips for determining if a sand dollar is living or dead:

If you happen to come across a living sand dollar, act swiftly. "Sand dollars won’t survive out of the water for long," Rader explained. "If you find a live one on the beach, gently return it to the ocean."