You live in a world of physical phenomena: surrounded by objects of all sorts, suffused by electromagnetic radiation, buffeted by waves of pressure propagating through the air and awash with tiny organic molecules that waft on it. Your senses are exquisitely attuned to perceive some of these things — certain frequencies of radiation become a beloved face, a mess of floating chemicals resolves into the scent of baking bread — but many others fall outside the narrow band of your perception. Without specialized equipment, you are quite literally blind to the ultraviolet or infrared and deaf to the ultrasonic cries of rodents or the infrasounds of elephants and whales. And forget about electric and magnetic fields; they’re so far outside our actual experience that we don’t even have a word for our inability to sense them.
This book is a guide to the physical world and how animal senses perceive it, with plenty of fascinating descriptions of biomechanics and organic chemistry. More than that, though, it’s an invitation to imagine what it might be like if our senses worked differently. Borrowing a term from early 20th century Baltic German zoologist Jakob von Uexküll, Yong describes the “sensory bubbles” of our Umwelt: like the blind men and the elephant, we have access to only a fraction of the available data, but it seems like the whole world.
We have pretty good noses and exceptionally sensitive fingertips, but the human Umwelt is dominated by sight. Not so for many other creatures, for whom touch or scent is more important — and it’s hard to overemphasize how differently other senses work. Light travels rapidly over great distances, but it can be easily blocked and it vanishes quickly and with little trace. Smells, on the other hand, seep and spread. A barrier impenetrable to sight poses no difficulty to scent; odorant molecules are so small they’re virtually impossible to entirely block, and they move around corners and through darkness as easily as they do in straight lines. But even more importantly, they linger. An Umwelt where scent reigns is one of layers, of history, of trails that slowly waft and dissolve over the course of hours or days. What would your relationship to time and space be if you came to the world nose-first?
And then make it even weirder: what if we could interpret the pressure waves of water moving between sand grains to find clams buried deeper than our probing fingers can reach, like the way the red knot can with its bill? What if we could feel the tiny air currents of an insect in flight, or the track the passage of a fish through water by the turbulence it leaves behind?
It’s difficult to imagine, and so we often don’t. After all, we have remarkable trouble wrapping our heads around other humans whose culture differs from our own; how much harder with something thoroughly alien? Maybe it’s no surprise that while the monsters we come up with may look different, they often act basically like “humans but” — human but larger, human but with big teeth and wings, human but with face tentacles and mind control. But they needn’t! Think of the (seemingly) simplest of additions, the ability to see in the dark. It adds tactical complications, sure, but it would do more than that: depending on how the dark-vision works, it can change nearly everything. Pit vipers use (you guessed it) specialized pits to “see” in infrared, but only at very low resolution and very close range. Cats and many other mammals have a reflective layer behind the retina that sends back light to be gathered a second time; in a reindeer, it grows and changes during the cold dark winter. Bats and dolphins “see” by echolocation. The golden mole finds mounds of dune grass amidst the sands of its desert home by listening for the ground-borne vibrations caused by the wind rustling the grass. Each one of these senses enables a creature to navigate a lightless environment much better than you can, but each also makes its world strange in ways you’d never think of — and which are therefore much more fun.
Just to whet your appetite for this book, I’ll leave you with a few animals.
Here’s the emerald jewel wasp:
The wasp — a beautiful inch-long creature with a metallic green body and orange thighs — is a parasite that raises its young on cockroaches. When a female finds a roach, she stings it twice — once in its midsection to temporarily paralyze its legs, and a second time in its brain. The second sting targets two specific clusters of neurons and delivers venom that nullifies the roach’s desire to move, turning it into a submissive zombie. In this state, the wasp can lead the roach to her lair by its antennae, like a human walking a dog. Once there, she lays an egg on it, providing her future larva with a docile source of fresh meat. This act of mind control depends on that second sting, which the wasp must deliver to exactly the right location. Just as a red knot has to find a clam hidden somewhere in the sand, an emerald jewel wasp has to find the roach’s brain hidden somewhere within a tangle of muscles and internal organs.And a whale:
Fortunately for the wasp, her stinger is not only a drill, a venom injector, and an egg-laying tube but also a sense organ. Ram Gal and Frederic Libersat showed that its tip is covered in small bumps and pits that are sensitive to both smell and touch. With them, she can detect the distinctive feel of a roach’s brain. When Gal and Libersat removed the brain from a cockroach before offering the roach to some wasps, they repeatedly stung it, trying in vain to find the organ that was no longer there. If the missing brain was replaced with a pellet of the same consistency, the wasps stung it with the usual precision. If the replacement pellet was squishier than a typical brain, the wasps seemed confused and kept rooting around with their stingers. They knew what a brain should feel like.
The scale of a whale’s hearing is hard to grapple with. There’s the spatial vastness, of course, but also an expanse of time. Underwater, sound waves take just under a minute to cover 50 miles. If a whale hears the song of another whale from a distance of 1,500 miles, it’s really listening back in time by about half an hour, like an astronomer gazing upon the ancient light of a distant star. If a whale is trying to sense a mountain 500 miles away, it has to somehow connect its own call with an echo that arrives 10 minutes later. That might seem preposterous, but consider that a blue whale’s heart beats around 30 times a minute at the surface, and can slow to just 2 beats a minute on a dive. They surely operate on very different timescales than we do. If a zebra finch hears beauty in the milliseconds within a single note, perhaps a blue whale does the same over seconds and minutes. To imagine their lives, “you have to stretch your thinking to completely different levels of dimension,” Clark tells me. He compares the experience to looking at the night sky through a toy telescope and then witnessing its full majesty through NASA’s spaceborne Hubble telescope. When he thinks about whales, the world feels bigger, stretching out in space and time.
Whales weren’t always big. They evolved from small, hoofed, deer-like animals that took to the water around 50 million years ago. Those ancestral creatures probably had vanilla mammalian hearing. But as they adapted for an aquatic life, one group of them—the filter-feeding mysticetes, which include blues, fins, and humpbacks—shifted their hearing to low infrasonic frequencies. At the same time, their bodies ballooned into some of the largest Earth has ever seen. These changes are probably connected. The mysticetes achieved their huge size by evolving a unique style of feeding, which allows them to subsist upon tiny crustaceans called krill. Accelerating into a krill swarm, a blue whale expands its mouth to engulf a volume of water as large as its own body, swallowing half a million calories in one gulp. But this strategy comes at a cost. Krill aren’t evenly distributed across the oceans, so to sustain their large bodies, blue whales must migrate over long distances. The same giant proportions that force them to undergo these long journeys also equip them with the means to do so—the ability to make and hear sounds that are lower, louder, and more far-reaching than those of other animals.
Back in 1971, Roger Payne speculated that foraging whales could use these sounds to stay in touch over long distances. If they simply called when fed and stayed silent when hungry, they could collectively comb an ocean basin for food and home in on bountiful areas that lucky individuals have found. A whale pod, Payne suggested, might be a massively dispersed network of acoustically connected individuals, which seem to be swimming alone but are actually together.
by Jane Psmith, Mr. and Mrs. Psmith's Bookshelf | Read more:
Image: uncredited
