Sand Dollars

Treasure trove.

That’s how I would describe beaches in South Carolina during the 80s. Many of them are still beautiful, but there’s less of the pristine landscape I remember seeing when my family had the opportunity to visit the ocean.

Rental properties and hotels have infringed upon those beaches today, but my memory still contains white sand and clear water… and countless treasures washed onto the shore.

One of my favorite things to do at the beach was to pick up shells and other fossilized (or ossified) animal remains. At one point, I had a little tool cabinet with drawers for each type of shell I found. Biology wasn’t always my primary area of interest, but it was everywhere I looked, so it was always a subject of study.

There was one find that would always delight me, especially when the remains were unbroken. This was a sand dollar, a former creature that came to resemble a bleached-white coin of some kind.

European explorers were reminded of the Spanish dollars that became the most widely used currency in the world for more than a century. By the 19th century, English speakers had begun to call them sand dollars, and that’s what they were called when I was introduced to them as a kid.

I was intrigued by the symmetry of the disc. It seemed like something that was too perfect for mother nature to make—those regular, repeating patterns from the radial symmetry made it seem even more manmade to me, and the color seemed too pristine and bright to be natural.

I’m sure that I knew sand dollars were sea urchins, like starfish, but I have little memory of learning this as a kid. You can see the five arms projecting outward from the center that mirrors a starfish’s structure, but they’re also related to sea cucumbers and other spiny critters that live at the bottom of the sea.

Sand dollars have a spine that is on the outside. You can imagine that one giant spinal prison wouldn’t work well for most animals, and you’d be right to guess that sand dollars don’t have such rigid exoskeletons. Instead, they’re more like bristles of a brush—flexible enough so that the animal can eat, reproduce, and all that.

However, once you see the ossified remains (hardened skeletons), the bristles are now blended together into one mass that makes up one unit. That’s what I picked up on the beach all those years ago: these were skeletons, not entire creatures I was collecting.

The rest of the animal has almost always already decomposed by the time you find a sand dollar on the beach, but not always. You might find a living sand dollar, but usually only after a big storm, where things from the floor of the ocean have been stirred up and washed ashore.

Sand dollars do all sorts of cool things while they’re alive! If they need to hide from predators, they can swallow sand so that they sink to the bottom, where the sand around them can obscure the view of something trying to eat them.

For their own feeding needs, sand dollars kind of scoop food upward with their arms, into their mouths. These mouths are located on the bottom side, and sand dollars have little grooves that lead directly in there, so when they swoosh the water around with their arms, their future lunch get a little push down that conveyer belt.

As a child, I saw only the bleached skeletal remains, and I was fascinated enough to want to collect and study these wonderful things. Today, I have another chance to be in awe of sand dollars.

Do you remember sand dollars? Did you ever collect shells as a kid?