The Magnetism of Eels

In a large bay along the Muhheakantuck, standing in the thickness of a partially exposed mud flat, my natural history students and I pull up a net pulsing with glass eels. Glass eels are tiny, transparent baby American eels, Anguila rostrata, and we are assisting members of the American Eel Monitoring Project, one of the longest-standing such programs in the country. Based at Hudsonia, an environmental nonprofit in Annandale-on-Hudson, the monitoring project seeks to document the American eel population and help facilitate its recovery. Beginning in the 1970s, populations of three different Anguila species—A. anguila, A. japonica, and A. rostrata—crashed dramatically following intensive, industrialized fishing targeting them. In addition to overfishing, habitat destruction and water pollution have contributed to declining eel populations, leading all three species to be listed as endangered on the International Union for the Conservation of Nature Redlist.

As part of a class I teach at Bard College, I arranged for my students to volunteer on an “eeling day.” Eeling days happen mostly on Fridays during the spring, but the time of day depends on when the moon’s gravity pulls the water back toward the ocean; making plans based on the lunar cycle felt fitting for this class. Standing in the muck, wearing oversized waders, we wet our hands and carefully pluck each writhing baby eel from the net, slipping them into a bucket for counting and documentation. They are tiny, about two inches long, entirely clear except for their spine and large, black eyes set cartoonishly on their little faces. I can imagine being confused about all the effort expended on these fish. But holding one of these creatures, I am taken by a familiar feeling: a being’s evolutionary story, laid out in my palm, is so unbearably beautiful—and mind-achingly improbable—that I become keyed into some amorphous, inarticulable truth. I think this truth has something to do with the meaning of life, but the way it is hemmed with a sense of grief makes me unsure. As much as I would like to articulate the pang of knowing I feel in these moments, as much as I would like to make it material, I cannot. But what I can do instead is tell you a story of the American eel.


During the Wisconsin Glaciation period that began about seventy-five thousand years ago and ended about eleven thousand years ago, the entire northeastern region of Turtle Island, now referred to as North America, was under a mile of ice. The tremendous weight of frozen water moved with the flux of phase changes—crushing, pushing, carving, churning, and dispersing earthly materials. The geological story can be sensed in the region’s soft mountainscapes and erratically plunked boulders, as well as the enormity of the Muhheakantuck, later called the Hudson by colonizers. This river was formed during glacial retreat, dug out by a glacier pulling north during a period of increased global warmth. The river is long, with its headwaters in the Adirondacks, running over three hundred miles to the Atlantic Ocean. It is referred to as a “drowned river,” due to the ocean’s upriver encroachment, commingling salt and fresh waters. The moon’s tidal influence shapes the dynamics of the Muhheakantuck, with a change in tide either exposing vast stretches of mud flats in the bays or swallowing them entirely. This is how the Muhheakantuck received its name in the Munsee language of the Lenape: the river that flows both ways.

Something about the size of the glass eels—and that their journey occurs underwater—disrupts my expectations of the limits of biological possibility.

Some fish spend their whole lives in freshwater, while others live entirely in saltwater. And some, like American eels, are diadromous, which means that their life cycle involves living in freshwater for one phase and saltwater for another. More specifically, eels are referred to as catadromous fish, meaning they are born in the ocean and then migrate to freshwater. This is opposite to anadromous fish, like salmon, which are born in freshwater and then migrate to the ocean. Catadromous species are much less common than anadromous species, as most fish species are descendants of fish that evolved in freshwater. This shift from freshwater to saltwater marked an adaptive transition that led to the vast numbers of fish species living in the ocean presently.

Glass eels arrive into consciousness somewhere near the Bermuda Triangle, in the Sargasso Sea. That is where the adults spawn, presumably all together in an orgiastic fantasia. Then, shortly after birth, glass eels are called by their encoded ancestral knowledge to begin their migration to freshwater. The eels we scooped up in the bay were at the tail end of a yearlong swim. For one whole year, these minuscule, transparent beings dedicate themselves to this path, this destiny. That a creature only an inch or two long can endure this migration is part of my fascination with them. Many animals migrate over astounding distances, each a baffling display of adaptation, but something about the size of the glass eels—and that their journey occurs underwater—disrupts my expectations of the limits of biological possibility. With birds, we humans can relate partially to the visual capacities they rely on to guide them: the rise and fall of the sun giving directional information, the contours of mountain ranges and water bodies, and so on. Impressive, yes, but fathomable. Baby eels make me think of the Polynesian sailors who charted vast oceans using the constellations. How on earth, literally, could that be done?

The prevailing explanation for the migrational capacity of eels is that they have in their bodies something called magnetite. Magnetite is an oxidized iron crystal that, as the name suggests, is sensitive to the Earth’s magnetic fields. Magnetite and similar compounds are found throughout the tree of life, including in certain bacteria, fish, birds, insects, and humans. In animals, the crystals are typically inside or near our brains. While it has been suggested since the 1970s that many animals use some degree of magnetic sensing to make their migrations, overall the biology of this phenomenon is not well understood. There are debates as to whether the magnetite found in certain animals is functional, or if it’s just an incidental byproduct of metabolic pathways. What we do know is that the origin of magnetite is ancient. Iron is one of the most abundant elements on Earth and is an essential element in the functioning of all known life forms. At some point, perhaps billions of years ago, an ancient lineage of aquatic prokaryotic bacteria evolved to incorporate magnetite crystals into their single-cellular bodies. These bacteria are called magnetotactic, meaning moving in response to magnets, because they use these crystals to sense their planetary location and guide them to their desired habitats. In their bodies, certain proteins synthesize nanoparticles of magnetite, which are enveloped in a membrane and are called magnetosomes. About a dozen or so magnetosomes are arranged in a chain, and they can move like a needle in relation to the earth’s magnetic field—life’s first compass.

If you accept that symbiosis is a norm rather than an exception to the rules governing biological relations and species dynamics, then the Earth itself, as a collective, begins to appear less random and chaotic.

After these magnetic compasses evolved in bacteria, yet another astoundingly improbable (at least to me) event is believed to have occurred. Another single-cellular organism absorbed a magnetotactic bacteria and incorporated it into its own body. Instead of being digested, the bacteria not only survived in the body of the larger species, but persisted for generations. Over deep time, these two lineages of coexisting organisms became fully interdependent, and gradually the smaller magnetotactic species became more of a component structure than a distinct individual. The larger species, now imbued with the biological capabilities of its symbiotic partner, continued to evolve and diversify, giving rise to innumerable descendants and a vast array of lineages. This is a process called endosymbiosis. It is also through endosymbiosis that organisms have mitochondria, chloroplasts, and other cellular components. These remnant structures, while now fully incorporated into other species, still possess unique features, such as proteins and even DNA sequences, that tell their own origin stories. As humans, our evolution is entirely dependent on one bacteria’s failed meal.

The success of this new little magnetic quirk, as with all adaptations, was acted on by natural selection. The individual who first absorbed the magnetotactic bacteria benefited, at least marginally, compared to its kin. When that cell divided, the bacteria also divided, and suddenly there were multiple cells containing and benefiting from magnetism. And again, a marginal benefit played out under the slow and dispassionate machinations of natural selection, so that in each generation, the population of magnetized individuals grew, on and on, for millions and millions of years. Of course, other changes were happening too: other endosymbiotic events, other pressures and other rewards, eventually giving rise to many distinct kingdoms of life, full of magnetic beings.

Endosymbiotic theory—also known as serial endosymbiosis, or symbiogenesis—was largely established by evolutionary biologist Lynn Margulis in “On the Origin of Mitosing Cells,” an article published in 1967 in the Journal of Theoretical Biology, and in subsequent works. Margulis is also famous for her contributions to the Gaia hypothesis, which is the idea that Earth is, in some sense, a superorganism. If you accept that symbiosis is a norm rather than an exception to the rules governing biological relations and species dynamics, then the Earth itself, as a collective, begins to appear less random and chaotic. The planet and all of its emergent complexity becomes more like a being than an object. Central to this hypothesis—which was first developed by James E. Lovelock and later collaboratively expanded upon by Margulis—are the many roles and functions of microbes: first archaea and bacteria, and later fungi. The microbial realm orchestrates a chemical environment that self-regulates and self-​sustains conditions for life. Margulis rejected the hyperfocus of competition in ecological sciences, and instead pushed us, through highly rigorous study, toward a framework of mutualism, cooperation, and, frankly, vitality. Her paradigm-shifting theories were vehemently contested for many decades, and she was personally the target of near-constant criticism for her work. As researchers have compounded evidence in support of her theories over the past fifty years and more, Margulis has been referred to as a “vindicated heretic.”

Sometimes the circumstances of a person’s life can seem fated, pointed magnetically toward some purpose, so obvious it is written on their forehead.

In 2022, a group of researchers from Oregon State University published a study in the Proceedings of the National Academy of Sciences on the magnetite in salmon noses. Salmon are famous for their dramatic migration, and scientific interest in their magnetic sensing has existed for decades. This study looked at proteins in the magnetite structures and was able to genetically link those proteins to bacteria, providing strong evidence for the endosymbiotic theory. While the exact methods of the study have not been applied to other groups of animals as yet, it is logical to accept that all animals with specialized magnetite structures, including the American eel, obtained them from a common bacterial ancestor. In these migratory species, not only is the Earth’s magnetic field a source of active information in the midst of a journey, but the magnetite itself is seemingly capable of being imprinted by magnetic patterns. Eels may be born with a magnetic memory—similar to how human fingerprints form in the pressing and moving of the pads against the lining of our mothers’ wombs, becoming imprinted with the soft, rich contours of their internal space. The variable dynamics of ocean tides, the gravitational push and pull, the relational space of the moon and Earth and its iron heart are the topographies etched into crystals and passed down generationally.

Like salmon, eels have magnetite in and around their heads, positioned near their foreheads. This makes me think of the Armenian word ճակատագիր, which is pronounced cha-ka-ta-gyr. Ճակատագիր can be translated to “destiny,” but in Armenian it literally means “writing on the forehead.” Sometimes the circumstances of a person’s life can seem fated, pointed magnetically toward some purpose, so obvious it is written on their forehead. Sitting between the eels’ little eyes is the crystalline map their parents gave them before dissolving into the sea. Here’s how you get home.


Home, for me, is unclear. My ancestors were displaced from Armenia and from Ireland by the rampages of genocide and colonialism. Now I move around on stolen land. I do not fluently speak either of the languages of my ancestors, Western Armenian or Gaelic, which are dying and threatened languages, respectively, due to campaigns of death and assimilation. A great sadness for me is that I will never speak a language fluently in the ecological cradle from which it arose. Like other biological features, a language emerges in the context of its speaker’s habitat, a reciprocal engagement between human and landscape. The landscape reveals, the speaker tells, and vice versa. The landscape exerts power, but a gentle power, similar to that exerted by farmers in the Armenian Highlands, who chose for breeding the sweetest apricots, every generation, for thousands of years. Irish linguist Pádraig Ó Tuama describes Gaelic as a decidedly earthy language, one that translates the physical world very literally, sometimes severely. Interviewed by the podcast For the Wild, he explains that the Gaelic word for the plant heather (Calluna vulgaris) is fraoch, which translates to “fury.” A foreigner to the land may look out across the rolling hills of pastel fraoch and see it as soft and beautiful: heather. A person familiar with the land will know that those visually inviting vistas are actually full of brutally sharp plants that bleed the tongues of sheep: fraoch. The British colonial aim of language eradication was made easier by the fact that, up until the 1800s, Gaelic was a predominantly spoken language. Criminalizing Gaelic and forcibly converting the earthy, place-based names of Irish communities to English names not only disoriented people socially and economically, but damaged their knowledge of their landscape. I see this loss as reciprocal, a violence felt both by the people and the landscape. I haven’t visited Ireland, but when I visited Armenia, I couldn’t contain my desire for belonging. I wanted to walk in the mountains and feel something tremble, something to tell me with total certainty that I was home. I was unabashedly looking for magic: I expected to feel the land recognize me back, perhaps magnetically resonate with my body. As time passed and nothing like this happened, I felt afraid that I had been forgotten; too much time had passed, and my lineage was too fractured.

One day, after a morning of mushroom collecting in the foggy hills of Dilijan National Park, rain soaked, I stepped into a cavernous, unlit monastery built about a thousand years before the genocide. From within the dark, someone lit a candle and passed it to me. I held the candle and cried. In the flame flickered an inextinguishable knowledge of belonging.

For decades, their secrets were safe in those mysterious waters, and I hoped we would never know them.

Home, for the American eels, is the gentle rivers and streams running from the eastern coast into the heart of Turtle Island. The calm waters are replete with nutritious invertebrates that the glass eels can eat upon arrival. Over time, the eels continue to grow in size and deepen in pigmentation. Passing from the glass stage to the yellow stage to the silver stage, their bodies increasingly match the silty riverbed, darkened by algae, plant tannins, and soil-enriched runoff. For as long as forty years, a single eel may live in a particular river or stream, growing up to five feet long. At some point after the eel is fully mature, signaled again by ancestral instructions and seasonal cues, they make the journey to sea. While much has changed for the eel, while a human generation has passed, the magnetic memory is still written on their forehead.


The objective of the eel’s second journey is to return to the spawning waters, where it will embark on a whirlwind of sex and death. Until late 2022, no one knew precisely where these waters were, though people had attempted, unsuccessfully, to find out. Once, a research group equipped about fifty adult eels with monitors before migration, but only a single eel survived enough of the journey to be tracked even remotely close to the suspected spawning waters. For decades, their secrets were safe in those mysterious waters, and I hoped we would never know them. Though a report on the location was released this year, I haven’t read it. My reverence for the sacred tells me that the eels’ clandestine location should remain a secret.

Because, until this year, no one had ever found the place the eels spawn, that also means there are no known human witnesses of eels having sex; as far as I know, no one has seen this yet. We know that eels appear to spend nearly their entire lives as intersex beings, with no observable secondary sex characteristics, and sex determination only arising in their last year of life. In order to prepare for the second migration, the eel is genetically programmed to stop eating and to structurally repurpose their digestive organs so that their body is packed with gonads, sexual reproductive organs. Even then, there are accounts of intersex adult eels, with functioning testicular and ovarian organs. The absence of obvious sexual reproductive organs in eels until this last year of life beguiled white male scientists for hundreds of years, so much so that it was dubbed “the eel question,” and elevated to almost fanatical heights. Understanding eel sexuality was the “holy grail of natural history,” according to writer and eel enthusiast Patrik Svensson.

The mysterious genesis of eels was first explained by Aristotle with the theory of spontaneous generation, which posited that multicellular organisms could arise from nonliving matter (often rotting organic material or soil) and did not need to descend directly from sexually reproducing parents. In Aristotle’s fourth century BCE text, Historia Animalium, translated by Richard Cresswell, he writes:

They originate in what are called the entrails of the earth, which are found spontaneously in mud and moist earth. They have been observed making their escape from them, and others have been found in them when cut up and dissected. These originate both in the sea and in rivers wherein putrid matter is abundant; in those places in the sea which are full of fuci, and near the banks of rivers and ponds, for in these places the heat causes much putridity. This is the mode of generation in eels.

Spontaneous generation was frequently applied to cryptic, often maligned or unsophisticated organisms, such as parasites, flies, and even barnacle geese (Branta leucopsis). This theory became firmly entrenched in biology until the eighteenth century, reinforcing the pre-Darwinian and Western imperial construction of the “great chain of being,” a hierarchy of life-forms organized by their perceived proximity to God. Humans, organized internally by race and gender, were at the top of the chain, with all other organisms beneath us. At the bottom were the least sophisticated organisms, which embodied, both literally and symbolically, their distance from the “image of God.” Jean Baptiste Lamarck, the nineteenth-century scientist famous for his debunked theories of evolution, mobilized the theory of spontaneous generation in his explanation of species hierarchy. Instead of our current evolutionary understanding of a unified tree of life, in which all species are descendants of a single common ancestor, Lamarck believed each species emerged independently from nonliving matter and was advanced up the chain by a “nervous fluid” that propelled it toward greater complexity and ultimate perfection. The simultaneous presence of “lower” and “higher” organisms—both terms still used in biology—was evidence of the differing emergence times of each species, and extinctions were moments of abrupt transformation. But with the groundbreaking publication in 1859 of Darwin’s On the Origin of Species, along with advances in microscopy and parasitological studies, spontaneous generation was discredited. Eel genesis would need a new explanation.

The eel question could just as well be called the human question.

Of all the scholars interested in the eel question, one of the most notable was Sigmund Freud. Freud’s early days of research were focused on the realms of natural history, and prior to his interests in the sex lives of humans, he was interested in the sex lives of eel folk. Following the discovery of ovaries in an eel by an Italian scientist, there was renewed conviction that eels must reproduce sexually. Freud spent a month, day after day, painstakingly slitting the bodies of hundreds of eels, looking for some proof of robust male sexuality, specifically testicles. After about four hundred dissected eels, Freud did eventually find testicles, tucked deep in the cavity of a single individual. At last, the sexual binary had been (partially) affirmed. And yet, argues historian Alexander Lee in an article for History Today, this conclusion seemed to bring Freud a degree of torment rather than satisfaction. Freud eventually removed the project from his list of publications and otherwise distanced himself from the work. Based on suggestions made by a friend of Freud’s, Lee speculates that this difficult, violent, and prolonged search for eel testicles triggered his own castration anxiety, one of his earliest psychoanalytic concepts.

Central to Freud’s obsession was a fundamental failing to account for (or accept) the potentially nonbinary and queer realities of life-forms. While undoubtedly interesting, the fact that eels are intersex for the majority of their lives is only shocking in the context of a heteronormative culture. The influence of heteronormativity is evident here in every step: the question asked, the investigative methods chosen, and the resulting panic when bias was not easily confirmed. How unscientific. Indeed, the eel question could just as well be called the human question. Our lack of imagination beyond boundaries and our violence extend to our own species as often as to the creatures we live beside.

Intersex people are fewer in number than those whose biology fits more neatly on one end or the other of the female-male spectrum, but the designation still encompasses millions and millions of people. Scholar of intersex, trans, and nonbinary experience Jennie Kermode writes, “Everyone has odd little genetic variations, but intersex variations are stigmatized because they’re a threat to social structures dependent on binary sex models. Other people’s sociopolitical anxieties lead to damage being inflicted on our bodies and psyches.” In the United States, as the U. S. State Department acknowledged in 2016, doctors routinely perform nonconsensual genital removal and sex assignment of intersex people. These procedures are often done on babies or young children who are not able to advocate for themselves, and they carry a high risk of complications, including total sensory loss in the genitalia. In some cases, the decision of which sex to assign is practically a coin toss, which can lead to a lifetime of gender dysphoria or repressed sexual expression.

In 2017, three U. S. surgeons general published a report advocating against such nonconsensual surgeries, arguing that, “While there is little evidence that cosmetic infant genitoplasty is necessary to reduce psychological damage, evidence does show that the surgery itself can cause severe and irreversible physical harm and emotional distress.” In medicine, as in U. S. society more broadly, we have decided that it is best to appear normal even at great cost—though, thankfully, this seems to be shifting a little. Much of queer advocacy can be understood as an attempt to establish or reestablish home; to find our place in things, both out in the world and within our own bodies.

To see your own biology mirrored in the body of a mysterious, metamorphosing, magnetotactic being is magic.

While it may not seem polite to compare intersex or other­wise queer people to eels, the mindset of reading comparisons to animals as insulting is also a function of colonialism and capitalism. It is the same body of logic that positions certain people beneath others and positions animals and nature beyond the human world beneath people. Domination requires imagining and constructing a distance, an other. Such mistreatment is often referred to as dehumanization or being treated as “less than human.” Culturally, we have established that language that likens humans to other life-forms permits violence against the group in question; this style of language is very frequently deployed against queer people, disabled people, and people of color. As feminist scholar Val Plumwood writes, “Thus, for example, behind the view that there is something insulting or degrading about linking women and nature stands an unstated set of assumptions about the inferior status of the nonhuman world.” By creating the myth that nature is subordinate to the unrivaled excellence of the human species, humans became alienated from nature, paving the way for justifying the domination and destruction of our companions.

To reckon with this, we must recast these comparisons entirely. To see your own biology mirrored in the body of a mysterious, metamorphosing, magnetotactic being is magic.


Like all life, eels hum with our common vitality—an energy as fundamental and universal as the genetic code itself, the transcribed and translated urge of pulsing continuity. An urge profound both in its simplicity and in its resultant complexity: to repeat a string of code. At some point eels are moved to burst forth from the relative safety of their silty homes and out into the oceanic expanse. From the little information we have, it seems the migration back to sea is a bit faster than their first journey, about forty-five days. The eels are larger now, perhaps more confident, guided magnetically back to their birthplace for their first and final romp. I am not sure if they know they are going to die, or if they know what death is, but it would be foolish of us to assume they do not.


I stand in the river with my students, in the chill of spring, and we turn up glass eels with almost every scoop of silt. They feel omnipresent, so much so that I fear crushing them with any given step. Once we have moved them into a single water-filled bucket, where they dart too quickly to count, one student scoops them with a small handheld net, and then, one at a time, allows them to wriggle free, back into the bucket. This delicate process requires only one person, but the rest of the group gathers closely around. Immediately, and in energized unison, the class begins counting each glass eel freed from the net. “One! Two! Three-four-five! Six! Seven-eight! Nine! Ten!” Everyone stands clustered, wanting to be helpful, to be bonded, both to the eels and to each other. Our group’s official count for the day—twenty-seven—is logged by the technician, and then the eels are placed in a small plastic bag for transport upstream, beyond the Sawkill Creek dam. The dam is too big for the glass eels to traverse, but the adults will have no trouble crossing over as they embark on their return migration.

Later we learn that, from within that single bay on the Muhheakantuck, the eel monitoring project recorded 3,408 glass eels that season. The project’s leaders describe this number as being so exceptionally high that it gives them cautious hope for the species’ trajectory toward recovery. Being trapped, netted, counted, and bagged is certainly not part of an eel’s natural migration, but it seems to be helping them. As I looked at their tiny bodies in the plastic bag that day, at their dark eyes and pinnate spinal columns, I wondered how they felt about their arrival upriver. When they sensed they had completed the map’s instructions and, in doing so, actualized their ճակատագիր, their destiny, did they feel something like triumph, or more of a sage satisfaction? They must sense their accomplishment somehow. Do the magnets go quiet, entering an extended dormancy, to be flicked back on at some encoded date? Or do they, instead, settle into a calming, assuring resonance? A signaling to the eels: You are home now. Grow old here.