What a Fish Knows: The Inner Lives of Our Underwater Cousins
By Jonathan BalcombeScientific American/Farrar, Strauss, and Giroux, 2016In 1949, Austrian ethologist Konrad Lorenz introduced his concept of the “baby schema,” which theorized that the large eyes, shorter snouts, and round wobbly heads of infant animals trigger caregiving urges in their parents. That this phenomenon crosses species lines is irrefutable, considering how much time we spend cooing at puppies and kittens—true fur babies—and any adult creature possessing a hint of benign fluffiness. If Lorenz were alive today, he'd nod in sage commiseration at our vast internet cache of videos and memes celebrating owls, raccoons, pigs, hedgehogs, rabbits, and ducklings (to name a few, in this reviewer's order of Descending Cuddliness).How about fishes? The puffer gracing the cover of Jonathan Balcombe's new book, What a Fish Knows, stares out with a rascally mien, as if daring us to deny that he is, indeed, cute. With both eyes facing front, playful spots and stripes, and translucent fins whirling, you could say he's all wobbly head. Might your first instinct be to pet his forehead, rather than see him sautéed on a plate?Balcombe, a Humane Society ethologist who's written about animals as sentient individuals of emotional complexity in Pleasurable Kingdom (2006) and Second Nature (2010), favors petting. Now he aims to show, through both the latest science and fabulous anecdotes, that “fishes are not just sentient, but aware, communicative, social, tool-using, virtuous, even Machiavellian.” Like author Sy Montgomery's foray into similar pools with last year's National Book Award finalist, The Soul of an Octopus, Balcome's What a Fish Knows is meant primarily for those who treat the ocean like a buffet table, rather than the fascinating, fragile alien world that it is.For example, it shouldn't surprise animal lovers to learn that male puffers, while courting females, make sand art on the ocean floor. Sandy mandalas are created when the puffer swims on his side while fluttering a pectoral fin, and are further beautified with bits of crushed seashell sprinkled in the center. Balcombe reveals this elaborate courtship gesture, akin to the architectural flourishes of bower birds, late in the book, in a chapter focused on fishes' sex lives. He begins his case for piscine equality with personal stories meant to resonate with the maximum amount of readers, including fishing at summer camp—and watching caught animals knifed in the skull—as well as his accidental shattering of a goldfish bowl in elementary school.Before Balcombe's swift, effective prologue is through, he presses us to imagine just how much 100 million tons (approximately 157 billion individual fishes) amount to—for that is the estimated annual haul of commercial fisheries worldwide. These individuals die miserably from “asphyxiation by removal from water, decompression from the pressure change of being brought to the surface, crushing beneath the weight of thousands of others hoisted aboard in massive nets, and evisceration once landed.”Balcombe then moves into the historical essentials of the fish as an organism, how bony fishes (teleosts) ring the world with 31,000 species, and cartilaginous fish (like sharks and rays) number around 1,300. The Cambrian period, 530 million years ago, is when the first fishlike creatures appeared. Then in the Silurian, 90 million years later, these creatures developed jaws, initiating the eat-or-be-eaten cycle that led to the explosion of fish species in the Devonian period.Humanity has only been around for 200,000 years. We've explored less than five percent of the Earth's oceans, which makes its depths a genuinely alien realm. That we should respect the fish as one of evolution's most elegant and versatile designs—instead of ripping giant nets across the ocean floor to cull as many as possible—does not, unfortunately, go without saying. Aside from relating stories by those who live and work with fishes about the animals' desire to be petted (the way any dog does), Balcombe tackles stereotypes about them being cold-blooded dimwits, unworthy of our moral consideration, in two main ways.First he describes a variety of fishes simply as they are. In doing so, we can't help but be astonished by creatures like the flounder, who experiences the migration of one eye to the opposite side of his face prior to adulthood. This happens in conjunction with another super-power, pigment manipulation (via cells called melanophores), which helps flounders take on the coloration of their surroundings. Other fishes are so strange that, were they featured on The X-Files as monsters-of-the-week, you'd have to ask, “Who comes up with this stuff?” Here Balcombe describes the sexual parasitism of certain male anglerfishes, who are less than half an inch long,
but what they lack in size they make up for in the sheer audacity of their mode of existence. On finding a female, males of some deep-sea anglerfish species latch their mouths onto her body and stay there for the remainder of their lives. It doesn't matter much where they fix their bite on the female—it could be on her abdomen or her head—they eventually become fused to her. Many times smaller, the male resembles little more than a modified fin, living off her blood supply and fertilizing her intravenously. One female may end up with three or more males sprouting from her body like vestigial appendages.
Balcombe's other scientific sortie on fishes' behalf is to describe their sensory world—what German biologist Jakob von Uexküll called the umwelt—and how it compares with our own. One of the biggest differences between humans and fishes is that we are trichromatic, having three types of cones in our eyes for detecting color, and they are tetrachromatic, possessing four. This allows for the detection of ultraviolet light, reflected by the faces of certain species and used by individuals to recognize each other.As if navigating a UV world didn't require a miraculous kind of intelligence by itself, fishes also create mental constructs, a key component of sentience. While decision making in laboratory exams—for food rewards—fishes can be deceived optically, using both the Ebbinghaus and Müller-Lyer illusions (the former involves circles of various sizes, the latter uses lines of varying length). Our underwater cousins, infamous for their supposed three second memories, couldn't master and/or fail a food-reward test unless they developed notions about, and then acted upon, the answers.Though Balcombe offers dozens of examples that illustrate awe-inspiring fish abilities on par with the human talents of writing and composing music, a few stand out. One is how some fishes smell. Salmon, sharks and eels can detect the scents of predators, prey, and their own species from absolutely minimal portions. Salmon can detect two-thirds of a drop of concentrated sea lion scent in an Olympic-size swimming pool. Eels can detect their home water using one-ten millionth of a drop. If the noses of these fishes seem astoundingly fine-tuned, evolution has a further surprise (as it usually does). It comes in the form of biogenic magnetite crystals, which certain bats and pigeons use to detect the Earth's magnetic fields. Balcombe tells us that long-distance swimmers like sharks, eels, and tunas have
Single cells containing microscopic magnetite crystals [that] act like compass needles. By isolating cells from the nasal passages of trouts (very close relatives of salmons) and exposing these cells to a rotating magnetic field, a research team from Germany, France, and Malaysia found that the cells themselves rotated. The magnetic particles are firmly attached to the cell membrane, and by constantly pulling toward magnetic field lines, these particles generate torque on the cell membrane when the salmon changes direction. That torque must be directly transmitted to stress-sensitive transducers of some kind, because evidence shows that the salmons can feel it.
Notice that Balcombe doesn't detail what “isolating cells from the nasal passages of trouts” actually entails. Perhaps it involves a non-invasive electronic scan of some kind? Judging by the author's horrific descriptions of other tests, executed to prove that fishes can feel pain, I'm probably being naive.Whether or not fishes experience agony, or merely react to it like robots, is an inane bit of obfuscation meant to validate both commercial and recreational fishing the world over. Fishes, like all vertebrates, are opioid-responsive, meaning that when injured their bodies are capable of chemically dulling a fire set in the nervous system. More pointedly, doses of lab-administered morphine work on fishes after lab-administered injections of acid and bee venom cause them injury. Sadly, such tests are necessary if scientific consensus is to translate into public policy. More people love eating delicious fish, and enjoy relaxing by the lake with their rod and tackle box, than are willing to bow to the common sense that if something is alive and can make eye contact, it probably wants to be left unmolested as much as you do.Once What a Fish Knows covers the animals' umwelt, the bodily experience, we're treated to the intricacies of their social and emotional realms. Balcombe relates anecdotes by fish owners whose pets grew anxious when tank mates were displaced, or when one owner himself changed his room around—and his cichlid Oscar began frequenting the other side of the tank to see him better. At a small pond in Pennsylvania, a librarian saw one fish use careful nudges to help a tilting companion stay upright.These behaviors are fairly intimate, and it's not likely that scientists will ever induce them in even the coziest artificial setting. There is, however, one natural fish environment that is like a laboratory unto itself: the reef. One of Balcombe's most dramatic examples of fish intelligence and emotion deals with cleanerfishes, who remove parasites, dead skin, and algae from the bodies of clients. These cleaners, working best and most competitively in reefs, follow exacting principles while operating what amounts to a small business. Cleaners must be fast, fair, and loyal to returning clients because their reputation is at stake. Those who nip their clients while cleaning (a fish's coating of mucus is quite nutritious) risk being avoided.Some readers will learn about cleaners, lovelorn pets, and sand-decorating puffers and dismissively answer that food and sex are a fish's prime motivator, as they are for any animal. A multitude of readers will encounter passages about vessels that dump dead by-catch (accidentally netted animals) back into the water as waste, and shrug. Yet the author maintains a patient and hopeful tone throughout What a Fish Knows, even when confronted by the devastating reality of ocean acidification and collapsing fish stocks around the world. He says,
Knowledge is a powerful thing; it informs ethics and fuels revolutions—witness the end of colonialism and institutionalized slavery, the advancement of women's rights, and the establishment of civil rights for African Americans. These were triumphs of reason stoked by a growing sense of moral revulsion. Injustices, be they driven by greed, narrow-mindedness, prejudice, or all three, wither in the face of informed reason. The color of one's skin, one's religion, or possession of a womb are simply no grounds for exploitation.
If more people realized that plastic, mercury, and a host of other poisons get cycled through the ocean, through fishes, and back into us, maybe books like this one would become rare. As it is, retailers and libraries have entire sections dedicated to the damage we've done to the environment and ourselves.____Justin Hickey is a freelance writer, and editor here at Open Letters Monthly.
