“During peak spawning, you can’t miss them,” I tell the group gathering at Plumb Beach. “But even when they’re not here in massive numbers, if you know where to look, this pretty dirty stretch of Brooklyn waterfront becomes something extraordinary.”
It’s late June, and twenty-three people have shown up for my monthly discovery walk—families with kids, photographers, biology students, a couple from Westchester. My daughter Greta, almost sixteen, is setting up our demonstration area while kids already cluster around her, drawn to her teenage patience with their questions.
Plumb Beach in late June is not what most people would call beautiful. Tucked between the Belt Parkway and Jamaica Bay, it’s more urban shoreline than pristine coastline—a narrow strip of sand littered with plastic bottles, old tyres, and the occasional shopping cart. The Manhattan skyline rises in the distance, a reminder that nature here exists in the edges, in the spaces we haven’t yet found a way to develop. The air smells like salt and gasoline, and the constant traffic hum from the parkway creates a soundtrack that never quite fades.
But it’s horseshoe crab spawning season, and we’re here to witness something that’s been happening since long before Brooklyn existed. I touch the place where my scar lies hidden beneath my shirt, feeling the ridge of reconstructed tissue. A year since the mastectomy. Clean margins, they said. No lymph node involvement. Yet here I am, leading walks about ancient creatures whose bodies have been harvested for human survival, wondering about the ethics of biological labour, about what it means to be simultaneously saved and saving.
Greta spots them first. “There!” she shouts, pointing at movement beneath the surface. She’s been coming as my assistant for a year now, and she’s better at this than I am—spotting them in the murky water, handling them with an unselfconscious confidence. As the wave recedes, it’s revealed: a horseshoe crab, bigger than most people expect, its domed shell glistening. And attached to its back, a smaller male.
“They’re coupled in what scientists call amplexed,” I explain to the group gathering around us. “The mating embrace that can last for weeks. The term comes from Latin, meaning ‘to embrace.'” A few people pull out their phones to take pictures, but most just stare, transfixed by watching them move together through the surf. The female, substantially larger, does all the work of locomotion while the male simply holds on, a passenger committed to the journey wherever it leads.
More pairs appear as the tide rises. I guide the group along the shoreline, pointing out pairs emerging from deeper water in steady procession, ancient and unhurried, following an impulse older than flowers. Some travel alone, others in chains of three or four, satellite males trailing behind the amplexed pairs like hopeful understudies.
“Can we touch them?” asks a woman with a Brooklyn accent.
“Gently,” I say. “They’re remarkably tolerant of us.” Greta wades into the shallows and carefully picks up a smaller crab, demonstrating the proper technique. “Hold them by the sides of their shell,” she tells a group of kids who’ve gathered around her. “Never by their tail—that’s called a telson, and you should never grab it.”
I watch her guide a nervous eight-year-old’s hands to the right position on the shell, her patience matching that of the ancient creatures we’re studying. We kneel beside a pair stranded by a receding wave, gesturing for the group to gather around. Up close, they’re even more prehistoric than most people imagine. The female’s shell is scarred and pitted, barnacles clustered along its edges like rough jewellery. The male, pressed against her back, seems almost delicate by comparison, his shell unmarked by age.
Three weeks ago, I lay in a donation centre watching my blood flow through clear tubing, each heartbeat sending another surge toward the collection bag. The nurse—Kenya, her name tag read—told me how beautiful it was that I’d never know whose life I might save. But watching the crabs tonight, I keep thinking about that word “donation,” how easily we apply human concepts to non-human situations. These crabs don’t choose to be lifesavers. They simply are, by accident of evolution, by the lucky coincidence of possessing something we need.
“They’re so patient, right?” I tell the group. “They don’t even notice us standing here. I mean, they’re on a completely different timeline than we are—they’ve been doing this for 450 million years. A few minutes of us gawking at them is nothing.”
The female begins to dig, using her front legs to excavate a depression in the sand. The group falls silent, mesmerised, as she settles into the shallow nest and begins to release her eggs—thousands of tiny green spheres, each one a potential life. The male responds immediately, releasing clouds of sperm into the water around them. Other males, the satellites we’d noticed earlier, crowd closer, adding their own genetic contributions to the mix.
“Mom, look at this one,” Greta calls from further down the beach, carefully carrying a particularly large female toward our group. “She’s got some serious mating scars.” The kids crowd around as Greta shows them the marks on the female’s shell, deep grooves where previous mates have gripped, season after season. “See these?” she says, tracing the worn places with her finger. “Every time she’s mated, the males leave these marks.”
I watch their faces as much as I watch the crabs. The wonder, the slight discomfort at witnessing something so intimate, the questions forming. It’s chaos and precision simultaneously. Random and ritualised.
In my medical sociology class last week, I showed my students photographs of horseshoe crabs lined up on metal racks, needles inserted into their hearts, their blue copper-based blood draining into sterile containers. About half a million crabs are bled annually. Thirty per cent mortality rate. “But it saves human lives,” Sarah, my pre-med student, said. “Every vaccine, every implanted device…” She wasn’t wrong. The crabs’ blood tests every injectable medication for bacterial contamination, including the ones that might have saved her life. Or mine. Or the life of whoever received my blood, tested safe by creatures who never consented to the exchange.
A wave crashes over the nesting site, and when it recedes, the pair is gone, vanished back into the deeper water. Only the disturbed sand remains, and somewhere beneath it, thousands of fertilised eggs begin their improbable journey toward life.
I’ve been leading these summer walks at Plumb Beach for several years now, drawn back not just by the crabs themselves but by watching people encounter them for the first time. Having Greta as my assistant has added another layer to the experience—watching her develop her own relationship with these creatures, her own way of explaining their behaviour to younger kids. Each group brings different perspectives, different questions. The marine biology students want to know about moulting schedules and population dynamics. The families focus on the spectacle of ancient creatures in an urban setting. The photographers seek the perfect shot of amplexed pairs silhouetted against the urban skyline.
Each walk reveals new details, or rather, new ways of seeing the same ancient patterns. The way satellite males position themselves precisely at the point where eggs are released, maximising their chances of genetic success without the commitment of attachment. The patient efficiency of their movements, no energy wasted on anything that doesn’t serve survival. The scars that accumulate, season after season, marking previous embraces.
But it’s the questions people ask that stick with me afterwards. How long do they stay attached? Do the females choose their mates, or is it simply a matter of who grabs on first? What does it feel like to be carried by another creature for weeks at a time? I don’t always have answers, but the questions themselves feel important, even necessary.
On the drive home, Greta is quiet for the first few minutes, staring out at the lights reflecting off Jamaica Bay. She’s always more reflective after the walks, processing what she’s seen and heard.
“That little kid tonight,” she finally says. “The one who was scared to touch the crab at first? By the end, he was picking them up himself.”
“I noticed that too. You’re good with them.”
She shrugs, the way teenagers do when they’re pleased but don’t want to show it. “It’s just about not being afraid. I think that boys want to show they are tough, but they are scared until they get used to them.”
We drive in comfortable silence for a while, past the Belt Parkway exit where beach walkers are heading home with sandy shoes and salt-stained clothes.
“Mom?” Greta’s voice is thoughtful. “Do you think the crabs know they’re helping people? When do they take their blood?”
The question catches me off guard. It’s one I’ve wrestled with in my own research, the ethics of non-consensual biological labour. But coming from her, it feels different—less academic, more immediate.
“I don’t think they know anything about helping,” I say. “They’re just trying to live their lives. Reproduce, survive, follow the patterns their species has followed for millions of years.”
“But we’re part of their lives now, aren’t we? I mean, we depend on them.”
I glance over at her. At fifteen, she’s already thinking about connections in ways that took me decades to understand. “Yes. We’re all connected, whether we realise it or not.”
She nods, then goes quiet again. After a few minutes, she says, “Did you see that couple tonight? The really big female with the smaller male on her back? They are probably in like 50 different pictures now on Instagram. Horseshoe crab celebrities.”
“They are famous,” I agree.
“Yeah. But they had more important things to worry about than us.” She pauses. “I kind of respect that.”
