For Sharona Muir, the bestiary is a literary genre of its own. Her novel Invisible Beasts is part anthology and part field-guide, but mostly it's the story of a young woman who sees animals nobody else can. Her experiences unfold in the form of a scientific catalog of animals.

Invisible Beasts Explores the Evolutionary Biology of Imaginary Animals

These descriptions are sensitive and elegant. However, this book maintains a sense of polemical urgency, to which the very invisibility of the beasts it describes is a testament.

Invisible Beasts explores the development of Sophie's skills, and of her discovery of the next in her family to share this ability:

I come from a long line of naturalists and scientists going back many generations, and in each generation we have had the gift of discovering hard-to-see phenomena, from a shelled amoeba lurking between two sand grains, to the misfolded limb of a protein pointing to a genetic flaw. This book also follows a venerable family tradition, but one never exposed to public view. Perhaps "trait" would be a better word than "tradition." Every so often, that is, every second or third generation, someone is born in our family who sees invisible animals.

As is evident from the meticulous distinction Sophie makes between tradition and trait, this book hews to evolutionary rules. These fantastical creatures follow the laws of natural selection, even in their invisibility.

The entry for "Feral Parfumier Bees" describes a bee colony, isolated in the Pleistocene:

Invisible, or Parfumier, Bees are natives of Asia, where they likely spring from the oldest lineage of honeybees, the red-bellied dwarf honeybee, Micrapis Florea. Though noble in their antiquity, Micrapis have never been the brightest bees on the planet—they never learned to waggle-dance, for example.

Invisible Beasts Explores the Evolutionary Biology of Imaginary Animals

Image via BiblioOdyssey

Sophie's biologist sister, Evie, offers, throughout the text, scientific explanations, and sisterly wit, even though she lacks the sight that her sister possesses: "What that means," Evie says, explaining the term escalator to extinction, "is, like, birds follow the plants and animals they eat into cooler climates…for which they haven't evolved."

As with the bees, the evolution of invisibility sometimes appears as itself an adaptation, for animals that struggle in their environment, whether that's the Asian bees that evolve into parfumiers rather than honey-makers because of their subsistence on unfamiliar resins, or the Pluricorn, a "wretched" animal barely clinging to the survival of its species:

Craning into the leafage, he sported a barbed brow horn, a fringe of curly tusks, a horn projecting from his chest, and big spurs, like ivory artichokes, on his rather knock-need legs. Over his head, a massive rack cast a grotesque, thorny shadow. Poor beast, he kept bashing himself on the hawthorn trunk, or tipping too far to one side and pawing rapidly to adjust.

Most of his equipment looks like antler tissue gone berserk, but his leg spurs look like naked bone protruding from under his skin. That has to hurt.

Invisible Beasts' publisher, Bellevue Literary Press, dedicates itself to books at the intersection of art and science, and it's in the descriptions of the invisible beasts, like the Parfumier Bees and the Pluricorn, that the affinity between the two seemingly disparate fields is revealed most clearly. Storytelling remains the only access to those real, visible species, now extinct, like the dire-wolves and the ground sloths that shared the Parfumier Bees' cave, or to the many living species most humans will never directly encounter, whether Rotifers or Chinese water deer, whose tusks the Pluricorn shares.

And it's through this affinity between storytelling and evolutionary biology that the book's urgency comes through. While the interlinked entries are packed with fanciful, beautiful, often humorous descriptions of invisible animals, the book's implicit argument is that all animals are invisible until humans recognize them, and so recognize their own dependence on a diversity of species, even those that seem invisible to most of us.

The stories Sophie tells imagine the animals' evolutionary path. The Fine Print Rotifer, included, punnily, under a section headed Invisible Beasts in Print, not because, like the other animals included in this section, this rotifer exists only in written records, but because it literally lives in, and on, print:

We are talking optimal foraging theory, which applies to all animal foraging, including your own shopping route. … And where do FPRs find their tasty ink molecules? In letters and words. So they develop foraging routes in the shapes of letters and words.

Fine Print Rotifers, in Muir's account, are responsible for the impenetrability of fine print because they subsist on the fine print of contracts, insurance policies, and mortgages.

Invisible Beasts Explores the Evolutionary Biology of Imaginary Animals

Despite the passion Muir has for her subjects and the stories of their evolution—"Who could not love a process that refined raw accidents into rare advantages?" Sophie asks—this book is neither didactic nor preachy, and Muir never lets the catalog structure make the narrative repetitive or plodding. Her storytelling is both funny and tender. In the section in which Sophie discovers a previously-unknown invisible species, the Hypnogator, Muir combines includes both danger and romance.

On trip to a Georgia sea island, Sophie discovers an invisible species she has never encountered. But its invisibility does not make the Hypnogator any more friendly than its visible counterparts:

the cold, ugly, glowing stones appeared. They blinked, left, left, right. I couldn't stop my mind from following their code, the code to confusion. I remembered that I'd locked onto Leif's kicking body, but a mental mist—like the one when you're about to black out—had kept me from knowing, except in glimpses, if I was still holding on.

The Hypnogator, like its visible brethren, is terrifying, and dangerous. There is, here, no excessive sentimentality about animals—whether visible or not. Rather, the attention to detail that our naturalist/narrator brings to her observations of beasts only she can see, also serves the narrative, developing characters and relationships that are flawed, poignant, beguiling.

This inventory of fantastical beasts allows Muir to tell a story at the level of the human, but also all of humanity. We don't, Invisible Beasts argues, have to be able to see animals to value them. Beasts exert profound influences on the way humans live, both in individual relationships and in our relationship to the world. And beasts, a category used here in all its expansiveness, includes everything from the human to the microbe. This book is a wondrous testament to those relationships, interdependencies, and affinities. Invisible Beasts makes the bestiary a document of profoundly human dimensions, and offers to all readers, whether devotees of science or of fantasy, very real pleasures.