Sand Dollars - On Ballast and Buoyancy

Paul's pic of a washed ashore sand dollar - topside

I failed at something not only important to me but to my sense of identity as a citizen-scientist and environmental educator. I’ve been nagged by it for almost two full years and just now I have the unexpected opportunity to correct it. I’ll confess it in a bit, but first I should share with you my first encounter with my natural teacher in this situation – living sand dollars. As a kid, our family visited the beach every August along the Outer Banks of North Carolina. Watching the calendar for that singular week was, for me, like waiting for Christmas. One August when I was what marketers now call a “tween” an adult relative took me and my friend to a place in the Bogue Sound where one could find sand dollars - those symbol-laden treasures of the sandy-mucky bottom. I begged my mom to let me decorate our Christmas tree that year, promising that I’d deck it full out with sand dollars.

Your experience with sand dollars now is likely on par with mine then; finding Communion-wafer-like, broken pieces of their tests (skeletons) on the beach and bleached-white whole disks of them for sale in shell shops along with the Christian-based “Legend of the Sand Dollar” that always goes something like this:

Snipped from this fellow: https://www.courageouschristianfather.com/the-legend-of-the-sand-dollar/#google_vignette

What we found that day, sifting through the shallow, muddy sand was quite a surprise. I’d locate one with my fingers and immediately feel hundreds of short, stiff, bristly spines pushing against my skin to try to escape my hunter’s clutch. Once I’d have them out of the water to place in our collecting bag I was confused by their chocolate-brown color. I just didn’t expect them to be so, well, alive. As we filled that bag with enough disks to decorate several holiday cedars I began to get filled with a sense of uncertainty. I wondered if what we were doing was somehow wrong. I may or may not have asked the adult about the ethics of our gluttony, but regardless I recall wanting to remain ignorant of the crime, if there was one. I really, really wanted to create this special tree for my mom who worked so hard yet with such joy to make our Christmases magically special. Still, back home in the Shenandoah Valley I felt immediate regret as I laid out to dry and bleach white their dead bodies. Come that Christmas Day all I could see hanging on our very live spruce who we would plant come January were contrasting symbols of death; living creatures sacrificed by my desire to please. Plus, I missed those magical, miniature worlds my mom would create with her no-two-alike ornaments gifted to her over the years by the kids she nurtured as our elementary school’s secretary and nurse. She was sort of everyone’s mom. Now, fast forward forty years and we come to my recent screw up and my present but risky opportunity to correct it.

Paul's timelapse of a live Sand Dollar on the move! Just as the world was closing itself down in spring 2020 due to the pandemic, Paul and I set sail with some new sailing friends to a very remote and protected place in Mexico’s Sea of Cortez. All of us were eager to set anchor so we could snorkel and free dive to experience the abundant and diverse sea life found there. One of my new friends popped up near me from a dive, very excited, and exclaimed to their partner, “Oh my gosh! Did you see that? That sea turtle let me ride her!”. I thought to myself, “No flippin’ way?! We shouldn’t be touching anything here, but a SEA TURTLE!? Do they not know how absolutely wrong that is?! Aside from harassing the wildlife, for crying-out-loud, sea turtles need to surface to breathe so grabbing onto one at depth could actually stress a sea turtle to the point of physical harm! Surely, everyone knows this.” I swam over to Paul and asked him if he heard what our new friend said. He didn’t and he asked me in his own disbelief if I was sure I heard correctly.

Paul's pic of a sea turtle surfacing for a breath.

Ah . . . Paul. He delivered a grain of doubt. A social-responsibility escape hatch. Surely, I heard incorrectly with the waves, wind, and my two layers of wetsuit hoodie. Hmmm. What do YOU think? Yeah, that was a load of BS, but I shoveled it on thick enough to talk myself out of confronting her and risking a new friendship wilting before it could bloom. Weeks later our boats parted ways, and just like with those sand-dollars, I knew I employed willful ignorance to evade responsibility. Who am I if not a teacher who shares her knowledge and love of all creatures in order to help protect them? Why, I’ve been asking myself for almost two years, did I make the choice not to speak up? Did I not want to hurt my friend’s feelings by making her feel bad or guilty? Did I not want to come across as a know-it-all-bossy-bitch-eco-cop? Some of both most likely. Like all of us I fear rejection, desire acceptance, and thus look for any excuse to shy away from conflict, even necessary conflict. But no matter my motivation, what I thought I heard required clarification and then response. I needed to speak my mind! I made a promise that if our boat lives should ever intersect again, I would need to make reparations to the sea and her life by speaking UP.

My pic of Triplefin at anchor near San Corlos, Sonora MX

Now, guess what boat just showed up and anchored beside us? Uh, huh. I’m in a self-made hot seat, my friends. I just radioed over to invite the turtle-grabber on a short hike in order to follow through on my commitment. But to this day – heck, this moment – I struggle with HOW to speak my mind when it conflicts with someone else’s mind or behavior. If I’m straightforward and bold I can seem judgmental and harsh. If I’m round-about and subtle I can sound unprofessional and not serious. And lately I seem to be even more socially anxious than ever in all ways. So, how then to speak to her?

Perhaps a lesson can be taken from those very alive sand dollars and their nifty adaptations to life in and on the swell-tossed muck. Like all echinoderms (the “hedgehog skin” sea urchins, sea stars, and sea cucumbers) their bodies have five-fold symmetry. That five pointed nativity star on their topsides are actually marks along their test (skeleton/shell) where their specialized breathing tube feet were connected in life. Yeah, they breathe through their feet . . . pretty nifty. So, how do they walk? Each of the small pores you see is where their short hedgehog-like spines were attached. Sand dollars use these spines to move over or through the sand (or to get away from grabby kid hands) and to feed themselves. Those spines end in tiny, tweezer-like tips (pedicellariae) that pick-up individual sand grains and pass them along like a conveyor belt towards their mouth near the center of their underside. Those pathways are what creates that poinsettia design on their undersides. And what a mouth! Those five doves of peace are actually their five teeth-like mouthparts that grind the sand in order to digest the bacteria and algae found on each grain. And one of the things I love about science is how we’re always learning new stuff. Recent studies show that sand dollar babies, the larvae, when in the presence of potentially predatory fish, detect the fishes’ mucous and within twenty-four hours begin making clones of themselves; increasing the chances that some of their selves will survive. Ok, that’s all super cool, but I’m stalling a bit. Where’s my sand dollar lesson in HOW to speak my mind when engaging in conflict?

By Louis Agassiz (Motier, 28 de mayo de 1807, - Cambridge, 14 de diciembre de 1873) - Leodia sexiesperforata, figura de Agassiz (1841) aparecida en: Agassiz, Louis (1841) Monographies d'échinodermes vivans et fossiles [Tome 2]. aux frais de l'auteur., Public Domain, https://commons.wikimedia.org/w/index.php?curid=27313880

Look at Agassiz’s side view illustration #3 above. You can think of sand-dollars as urchins who are sort of smushed, so that they can move streamlined through the sand. But do you see how from the side that gives them a rounded, hydrofoil shape like an airplane wing or sailboat sail to accommodate their internal structures? Unfortunately, that makes them susceptible to too much lift, so they evolved with a way to counter that buoyancy. Recall those holes that Christians see as symbols of stigmata. The slit-like holes help sand dollars stay grounded by balancing the water pressure above and below them, so they don’t get lifted up and whisked away in the water column whenever there’s a current. And extra-light-weight baby sand dollars (I think my tween-self crafted earrings out of them.) need even more weight to stay down so they have a special behavioral adaptation. The tiny newbies, we've recently found, actually pick and choose morsels of sand laden with the heavy, iron-rich mineral magnetite. They store the magnetite in special gut chambers to give themselves ballast so they don’t go sailing up, up and away.

As I now prepare to grab the turtle-grabber on my kayak and speak my reparations while hiking, I’m considering the sand dollar. I need to have enough levity to not scare my friend into defensiveness countered with enough weight for her to take me seriously. My recalling that she may have acted in ignorance with the sea turtle just like I did long ago with the sand dollars will give me the empathy and compassion to use as buoyancy. My knowledge of sea turtle biology and behavior will be my ballast to keep my feet on the ground of facts. Well, here I go to get her, right in the midst of this first draft . . . . drum roll . . . .

What a surprise! I wasn’t perfect in my delivery. I think my voice was a bit hyper-nervous-over-excited as I told her about how I had failed by not speaking up a couple years ago. But I must have done OK because she really wanted to understand how holding onto a sea turtle could harm them. She was effusive in her thanks for the information, grateful to now know that she shouldn’t do that again, and reminded me that my withholding my knowledge from her was also not honoring her desire to be informed and act righteously in this wild world. Plus she gave me a big belly laugh by remarking something like this: “It’s lucky I didn’t run into any sea turtles the past two years. Just think, I could’ve traveled all over grabbing sea turtles willy-nilly, scaring them to death! We both could’ve been condemned to e-turtle damnation for this and you speaking up saved us, Jo! And, then this crazy thing was revealed . . . .

We sat on the beach to talk a bit more before kayaking back in the dark. We discovered that we both had suddenly lost our moms on Christmas Eves decades ago when we were each still painfully young. Instead of pretty much ignoring the holiday like I historically have, I think this Christmas Eve I’ll craft some hand-sculpted, sand dollar cookies to hang from that straggling palo verde tree on El Tomate beach, make a fire there with my new friends, and share those cookies. They won’t be bleached white cookies, mind you. These cookies will be chocolaty brown in honor of very alive sand dollars.

My first batch of cookies!