Discovering Coquina Clams at Cocoa Beach

After 25 years of visiting Cocoa Beach, a discovery of coquina clams transformed my appreciation for the ecosystem, revealing its beauty, complexity, and intrinsic connections to life.

A Familiar Shore, Newly Seen

For nearly two and a half decades, I’ve strolled the sands of Cocoa Beach—since my first visit in March 2001—comforted by the rhythmic Atlantic waves and the familiar stretch of shoreline. I thought I knew this beach intimately; from the way the sunrise paints the water orange to the feel of wet sand under my feet. Yet it wasn’t until a clear morning in February 2025 that I recognized one of its tiniest treasures: the coquina clam. In the past, I might have walked past countless little shells and the tiny siphons and feet in the sand without a second glance. Now, with newfound awareness, I realize an entire world had been bustling at my toes all along.

February 2025: Discovering the Coquina Clams

Early one February morning, as the high tide receded, I noticed something magical happening at the water’s edge. Tiny coquina clams—each no larger than a fingernail—were emerging from the sand only to swiftly burrow down again between each wave.​

These living coquina clams were found in the receeding high tide on a February 2025 morning on Cocoa Beach, Brevard County, Florida

Their small wedge-shaped shells, in colors of pastel pinks, purples, yellows, and whites, peeked out for a moment and then vanished, synchronized with the pulse of the ocean. It was as if the beach itself had come alive with confetti-like jewels, re-positioning themselves with every ebb and flow. I stood entranced, wondering how I’d missed this subtle dance for so many years. That morning marked the beginning of my quest to learn about these little clams that had been hiding in plain sight.

Life Beneath the Sand

Once my eyes were opened, I began observing and researching the coquina clams’ hidden world. I learned that each delicate clam is a filter feeder, siphoning in microscopic phytoplankton, algae, and organic particles from the surf. This constant filtering not only feeds the clam but also helps clean and clarify the coastal waters by removing excess nutrients. Coquinas live a fast-paced, transient life by necessity: they typically survive 1–2 years in the wild and can endure a mere few days without the ocean’s moving water.​

No wonder they race to burrow when the waves recede—staying submerged is a matter of life and death, as they rely on the surf for both food and oxygen. In their brief lifespan, they continually ride the tides, migrate in swarms up and down the beach, and rebury themselves between each wave to avoid being swept away.

I found it astonishing that such small creatures possess the agility and tenacity to “surf” the waves and dig themselves back into wet sand within seconds, a graceful routine I had unknowingly witnessed that February morning.

Beyond their daily habits, coquina clams also undergo a remarkable life cycle beneath the sand. They spawn in the warmer months, releasing gametes into the water for external fertilization. The resulting larvae drift as plankton for a time before settling into the sand and metamorphosing into tiny clams. With no parental care to guide them these young coquinas must immediately fend for themselves in the surf zone. Perhaps it’s this independent, perilous beginning that drives them to cluster in large colonies—while they aren’t social in a communicative sense, hundreds of coquinas often live side by side in favorable spots, turning patches of wet sand into vibrant mosaics of color and life​.

Walking the beach now, I recognize these patches: slightly raised, pebbly areas that, when a wave washes over, suddenly bristle with tiny siphons and feet as the clams feed and reposition. It’s humbling to realize that under each footstep, an entire hidden ecosystem of coquinas might be thriving.

Shells on the Shore: Beauty and Predation

With my new awareness, even the empty shells strewn along the high tide line told a story. I began to collect some of the colorful coquina shells scattered on the sand, marveling at their variety—no two looked exactly alike. Some were solid orange or yellow, others striped with purple and white, each as delicate as a butterfly wing. Many of these shells were intact, evidence of clams that had lived out their short lives or perhaps fallen prey to gentle endings. Others, however, bore mysterious perfectly round holes on their surfaces. At first glance, I thought a tiny drill had punched through them, and in a way, I was right. Those small holes are the signature of predatory snails that haunt the sands: creatures like moon snails (also known as shark’s-eye snails) and whelks that prey on coquinas by literally boring into their shells. These sand-dwelling snails wrap themselves around a clam and use a tongue-like organ called a radula—akin to a miniature saw—to drill a neat hole through the coquina’s shell, aided by acidic secretions to soften the calcium carbonate. Once the hole is complete, the snail devours the clam from within, leaving behind an empty, perforated shell as a grim calling card of the food chain in action.

Seeing those tiny “murder holes,” as beachcombers jokingly call them, on coquina shells transformed my perspective on the shell collections I had casually admired for years. Each shell in my hand represented a life that had been an integral part of the beach ecosystem. Some had been snatched by shorebirds or fish the instant they were exposed by the retreating tide, becoming breakfast for a sanderling or a pompano. Others, as the holes revealed, had been victims of an even stealthier predator under the sand. It struck me that every fragment and hollowed shell on the beach is evidence of a relationship—predator and prey, life and death intertwined on the shore. Instead of seeing a random assortment of pretty shells, I now saw a record of the beach’s vibrant food web written in calcium carbonate. The realization filled me with both wonder and respect: this sunny tourist beach holds quiet tales of survival as dramatic as any wilderness, if one knows where to look.

The Coquina’s Ecological Role

As I dug deeper (both into the sand and the literature), I discovered that coquina clams are far more than a footnote in the beach ecosystem—they are a keystone of coastal ecology. By filtering plankton and detritus from the surf, countless coquinas collectively act as tiny water purifiers, helping maintain water quality along the shore. Their presence in large numbers indicates a beach’s health; in fact, abundant coquina populations signal that the beach environment is robust and unspoiled. A stretch of sand teeming with coquina clams suggests natural, shifting sands and minimal human interference, as these clams thrive best where coastal processes remain undisturbed. In this way, coquinas are like a barometer for the shoreline: if I continue to find them at Cocoa Beach, it means the beach is still alive and supporting complex life.

Coquina clams also form a critical link in the food chain. Numerous shorebirds rely on them as a food source—those flocks of little sandpipers and plovers skittering at the water’s edge have, all along, been feasting on coquinas right under my nose. Fish that patrol the surf, like the Florida pompano and various kinds of drum (whiting), gulp them up as the waves churn the sand​.

These coquina clam shells were found February 2025 on Cocoa Beach, Brevard County, Florida

Even ghost crabs and other scavengers benefit, feeding on clams that wash ashore. And of course, the predatory snails under the sand have a specialized taste for them. It’s a reminder that even a creature only an inch long can be a cornerstone of an entire food web, sustaining animals up the chain from mollusks to birds to fish. Standing on the beach now, I often pause and watch the frenetic chase of the shorebirds in the surf, aware that without the coquina clams beneath the foam, that familiar coastal ballet could cease to exist.

Humanity and the Coquina: Intertwined Histories

It’s not only animals that have interacted with coquina clams—we humans have a longstanding relationship with them as well. Historically, Floridians made use of coquinas as a food source. Local folklore and old recipes describe coquina broth and chowder, a delicate soup made by briefly boiling these tiny clams to extract their flavor.​

Because each clam is so small, you’d need hundreds to make a pot of soup, so it’s not a common dish today except perhaps as a novelty. Still, the idea that the sands I walk on could literally be cooked into a chowder is a charming and earthy connection between food and place. Early indigenous peoples and European settlers alike would have recognized coquinas as an edible bounty in times when every bit of protein counted.

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Humans have also found value in the shells of coquinas beyond admiring their beauty. Over time, vast deposits of coquina shells on ancient beaches hardened into a soft limestone rock called coquina stone (the term “coquina” itself comes from the Spanish for “shellfish” or “cockle,” reflecting its composition)​.

In a fascinating twist of fate, this sedimentary rock—essentially millions of fused clam shells—became a building material. Here in Florida, coquina stone was quarried and used to construct some of our oldest structures. The historic fortifications in St. Augustine, like Fort Matanzas and Castillo de San Marcos, were built from coquina stone, their walls made resilient by a matrix of coquina clam shells​.

I find it poetic that the same little clams I only just learned to appreciate have literally been the building blocks of human shelters that have stood for centuries. Even today, crushed coquina shells are used in landscaping and as decorative ground cover—perhaps you’ve seen driveways or garden paths that gleam with fragments of pink and purple shells.​

Our lives overlap with the coquina in subtle ways: from the architecture of coastal Florida to the aesthetics of our beach towns.

Modern conservationists note another connection: by protecting natural beach dynamics, we also protect coquina populations, which in turn supports the whole ecosystem. This means being mindful about coastal development, beach renourishment projects, and even how many shells tourists collect. I’ve become more aware that picking up a few pretty coquina shells as souvenirs is fine, but we must leave plenty behind for the beach to recycle and for other creatures to use. For example shorebirds glean minerals from them. The humble coquina clam has given me a new appreciation for how intimately tied human activity is to the smallest inhabitants of the shore.

Reflections: Wonder in the Little Things

My journeys to Cocoa Beach were enhanced: what began as a casual observation in 2025 has blossomed into a profound shift in the way I experience the beach. I feel as if I’ve been given new eyes—now I notice the glint of tiny shells in the sand and know there’s life (or a story of life) attached to each one. The joy of discovery I felt upon noticing the coquina clams has reignited a childlike curiosity in me. It’s astounding that after decades of visits, there was still a secret to uncover on those familiar shores. This realization makes me wonder: What else have I been missing? It’s a reminder that nature has layers upon layers of wonder, even in places we think we know intimately. Sometimes it just takes a shift in perspective, a bit of knowledge, or a quiet moment of attention to peel back the veil.

In reflecting on the coquina clams of Cocoa Beach, I’ve learned not only about a specific species and its role in the world, but also about myself and the value of lifelong learning. These clams, in their smallness and ubiquity, taught me to slow down and appreciate the intricate tapestry of life at my feet. Now, each time I visit the beach, I smile seeing the waves bring in that rush of foam and sand, knowing a hidden troupe of coquinas is hard at work filtering water, dodging predators, and holding up the very balance of the shore. I often kneel down now, running my fingers gently through the wet sand to feel them retreat, and I silently thank them — for cleaning the water, for feeding the birds and fish, for building historic forts (unbeknownst to themselves), and for showing me that wonder can be found in the smallest of places. Cocoa Beach, through the lens of the coquina clam, feels like a brand new world I’ve been lucky enough to discover, even after all these years​

I look forward to other hidden marvels awaiting discovery on my next visit.

References


Abbott, R. T. (1974). American Seashells: The Marine Mollusca of the Atlantic and Pacific Coasts of North America. Van Nostrand Reinhold Company.

Andrews, J. (1994). Shells and Shores of Texas. University of Texas Press.

Brusca, R. C., & Brusca, G. J. (2003). Invertebrates (2nd ed.). Sinauer Associates.

Denny, M., & Gaines, S. (2000). Encyclopedia of Tidepools and Rocky Shores. University of California Press.

Futch, C. R., & Burger, J. (1976). The ecology of coquina clams (Donax variabilis) in the southeastern United States. Marine Biology Journal, 34(2), 157-168.

Leal, J. H. (2002). Seashells of Southern Florida: Living Marine Mollusks of the Florida Keys and Adjacent Regions. Smithsonian Institution Press.

Mikkelsen, P. M., & Bieler, R. (2008). Seashells of Southern Florida: Marine Bivalves, The Bivalvia. Princeton University Press.

Morton, B. (1988). Particulate Matter Processing in Bivalves: An Overview. Journal of Marine Ecology, 19(3), 103-123.

Ruppert, E. E., Fox, R. S., & Barnes, R. D. (2004). Invertebrate Zoology: A Functional Evolutionary Approach (7th ed.). Cengage Learning.

Stanley, S. M. (1970). Relation of shell form to life habits of the Bivalvia. Geological Society of America Memoir, 125, 1-296.

Voss, G. L. (1980). Seashells of the Gulf and Atlantic Coasts. Houghton Mifflin Harcourt.

Wells, H. W., & Gray, I. E. (1960). Habitat selection and the distribution of the coquina clam (Donax variabilis). Ecological Monographs, 30(1), 55-77.

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Crystalline Secrets: The Art and Science of Whelk Shell Formation

As you stroll along the beach, the beauty of whelk shells captures your attention. Ever wondered how these intricate structures form? Dive into the secrets of their creation, from cosmic origins to mollusk mastery. Discover the fascinating world within their shells

Exploring the Formation of Whelk Shells


As I wander along the coast, the variety of seashells scattered across the beach fascinates me, particularly the whelk shells with their intricate designs and robust structure. This marvel of nature prompts me to delve into the science behind the formation of these shells, which are not just homes for the marine creatures but also a testament to the extraordinary processes that take place both within the organisms and across the cosmos.

The Architect: The Mantle of the Whelk


The journey of a whelk shell begins within the mollusk itself, specifically with an organ called the mantle. This organ is a marvel of biological engineering, responsible for laying down the calcium that forms the shell’s backbone. It secretes a matrix, a kind of biological scaffolding composed of proteins and polysaccharides, and then directs the deposition of calcium carbonate within this matrix to create the hard shell. The mantle’s work is meticulous, ensuring the shell’s growth and repair throughout the whelk’s lifetime.

The Building Blocks: Calcium, Carbon, and Oxygen


So why do the elements calcium, carbon, and oxygen play such a crucial role in shell formation? It’s a question of availability and suitability. These elements are abundant in the marine environment—calcium dissolved in seawater, carbon, and oxygen from both water and air. Their chemical properties allow the formation of calcium carbonate, a stable compound that can adopt various forms like calcite and aragonite, offering structural diversity for shells. Calcium carbonate’s moderate solubility enables mollusks to control shell formation precisely, and its biocompatibility ensures the process is safe for the living organism. Above all, the resulting crystalline structure provides immense strength and rigidity, a natural armor against predators and environmental challenges.

The Role of Calcium Carbonate


Calcium carbonate (CaCO₃) is not just a building block for shells; it’s a common substance that shapes our world. Found in rocks as calcite and aragonite, it forms limestone, the basis of pearls, and even the eggshells we encounter daily. This compound is an active player in both industrial applications and biological functions, serving as an agricultural amendment, a component in cement, and even a dietary supplement for humans.

The Mollusk’s Craft: Extracting from the Environment


Whelks are not alchemists; they do not create calcium carbonate from thin air. Instead, they are master extractors, pulling calcium and carbonate ions from their surroundings and depositing them as calcium carbonate to form their shells. The mantle is at the heart of this process, secreting proteins and enzymes to facilitate ion extraction from the water. The precise regulation of ion concentrations and pH ensures the calcium carbonate crystallizes in the desired form, perfectly tailored for the whelk’s protection.

Star-born Elements: The Cosmic Connection


It’s astounding to think that the elements composing whelk shells are not just earthly but cosmic in origin. The calcium (atomic number 20), carbon (atomic number 6), and oxygen (atomic number 8) that are so critical to these marine structures owe their abundance to the stars. The life cycles of stars, from their hydrogen (atomic number 1) and helium (atomic number 2) fueled births to the explosive supernovae and neutron star collisions that mark their deaths, generate and scatter these elements throughout the universe. These star-born materials eventually coalesced to form our solar system and Earth, providing the necessary ingredients for geological and biological phenomena, including the formation of the whelk shells I hold in my hand.

As I reflect on the shells before me, I am reminded of the interconnectedness of all things—from the inner workings of a tiny mollusk to the vast and violent furnaces of stars. These shells are not just remnants of life; they are cosmic artifacts, a reminder of our connection to the universe and the extraordinary processes that shape our existence.

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