excerpts from ed yong’s “an immense world: how animal senses reveal the hidden realms around us”

walk and discuss at eagle pond, barnstable: wednesday, june 5, 2024 at 10 am

Though it is not necessary to read the book ahead of time to participate on the walk, we encourage you to pick up a copy at Titcomb’s Bookshop in Sandwich on Route 6A. You will be amazed by this seminal work. Register for this special event here: https://blt.org

1. INTRO: [A large room, as big as a school gymnasium, is entered by seven animals - a bat, a bumblebee, an elephant, a rattlesnake, an owl, a mouse, and human….]

“These seven creatures share the same physical space but experience it in wildly and ponderously different ways. The same is true for the billions of other animal species on the planet and the countless individuals within those species. Earth teems with sights and textures, sounds and vibrations, smells and tastes, electric and magnetic fields. But every animal can only tap into a small fraction of reality’s fullness. Each is enclosed within its own sensory bubble, perceiving but a tiny sliver of an immense world.

There is a wonderful word for this sensory bubble - Umwelt. It was defined and popularized by the Baltic-German zoologist Jakob von Uexküll in 1909. Umwelt comes from the German word for “environment” but Uexküll didn’t use it simply to refer to an animal’s surroundings. Instead, an Umwelt is specifically the part of those surroundings that an animal can sense and experience - its perceptual world. Like the occupants of our imaginary room, a multitude of creatures could be standing in the same physical space and have completely different Umwelten.

Even when animals share the same senses with us, their Umwelten can be very different. There are animals that can hear sounds in what seems to us like perfect silence, see colors in what looks to us like total darkness, and sense vibrations in what feels to us like complete stillness. There are animals with eyes on their genitals, ears on their knees, noses on their limbs, and tongues all over their skin. Starfish see with the tips of their arms, and sea urchins with their entire bodies. The star-nosed mole feels around with their noses, while the manatee uses their lips. We are no sensory slouches either. Our hearing is decent, and certainly better that that of the millions of insects that have no ears at all. Our eyes are unusually sharp, and can discern patterns on animal bodies that the animals themselves cannot see. Each species is constrained in some ways and liberated in others.

“[Animals] move finished and complete, gifted with extensions of the senses we have lost or never attained, living by voices we shall never hear,” wrote the American naturalist, Henry Benton. “They are not brethren, they are not underlings; they are other nations, caught with ourselves on the net of life and time, fellow prisoners of the spender and travail of the earth.”

2. SCIENCE AS STUDIED BY SENSORY ATYPICAL SCIENTISTS, P. 13

When we pay attention to other animals, our own world expands and deepens. Listen to treehoppers, and you realize that plants are thrumming with silent vibrational songs. Watch a dog on a walk, and you see that cities are crisscrossed with skeins of scent that carry the biographies and histories of their residents. Watch a swimming seal, and you understand that water is full of tracks and trails. “When you look at an animal’s behavior through the ends of Thant animal, suddenly all of this salient information becomes available that you would otherwise miss, “ Colleen Reichmuth, a sensory biologist who works with seals and sea lions, tells me.” “It’s like a magic magnifying glass, to have that knowledge.”

Many sensory biologists have backgrounds in the arts, which may enable them to see past the perceptual worlds that our brains automatically create. Sonke Johnsen, for example, studied painting, sculpture, and modern dance well before he studied animal vision. To represent the world around us, he says, artists already have to push against the limits of their Umwelt and “look under the hood.” That capacity helps him “think about animals having different perceptual worlds.” He also notes that many sensory biologists are perceptually divergent. Sarah Zylinski studies the vision of cuttlefish and other cephalopods; she has prosopagnosia and can’t recognize even familiar faces, including her mother’s. Kentaro Arikawa studies color vision in butterflies; he is red-green color-blind. Suzanne Amador Kane studies the visual and vibrational signals of peacocks; she has slight differences inhere color vision in each eye, so that one gives her a slightly reddish tint. Johnsen suspects that these differences, which some might bill as “disorders” actually predispose people to step outside their Umwelten and embrace those of other creatures. Perhaps people who experience the world in ways that are considered atypical have an intuitive feeling for the limits of typicality.

3. SURFACE VIBRATIONS : FROG EMBRYOS:

….Frog embryos are neither as helpless nor as unaware as people thought. The embryos’ sensory bubble extends beyond the actual bubble in which they’re trapped. Light can pass through the translucent eggs, and chemicals can diffuse into them. But vibrations are what really matter. They pass into the eggs and into the embryos, which can distinguish between bad vibes and benign ones without and previous experience of either. A bite from a snake will trigger hatching. Rain, wind, and footsteps will not. Even when a mild earthquake rattled [the pond] the embryos did not react… Falling raindrops produce a steady pitter-patter of short, high-frequency vibrations. Attacking snakes produce lower frequencies and more complicated patterns, with prolonged bouts of chewing punctuated by periods of stillness. If [the scientist] edited gaps of stillness into rainfall recordings to make them feel more snake-like, the tadpoles found them scarier and were more likely to hatch. They can clearly sense the world before entering it, and they can use that information to defend themselves. They have agency. They have an Umwelt.

DISTINCTION BETWEEN SOUND AND SURFACE VIBRATIONS:

Airborne sounds are waves that oscillate in the direction of travel - imagine stretching and compressing a Slinky. Surface waves, by contrast, oscillate perpendicular to the direction of travel.

…Animals detect both kinds of waves with the same receptors and organs, like hair cells and inner ears.

For the longest time, researchers saw all kinds of drumming, thumping, shaking, and quivering body parts, and interpreted them as visual or auditory signals, while ignoring the surface waves that those movements produce. Every red-eyed tree frog cues into that sensory world from four and a half days of age, but generations of scientists ignored it. “We have encountered it, but we were not looking for it,” wrote ecologist Peggy Hill. It’s a lesson that sensory biologists, and everyone else, should heed: By giving in to our preconceptions, we miss what might be right in front of us. And sometimes what we miss is breathtaking.

ELEPHANTS:

In the early 1990s, Caitlin O’Connell spent weeks at a time sitting in a dank, cramped, half-buried cement bunker, gazing through a narrow slit at a waterhole. She had come to Etosha National Park in Namibia to study elephants and to find ways of keeping them away from croplands. In the meditative confines of her bunker, she got to know the local hers, and certain behaviors began to leap out. Sometimes, she noticed, an elephant seemed to sense something in the distance, freeze midstride, and lean forward with a foot propped up on its toenails….. The animals seemed to be listening with their feet but no one seemed to have noticed.

In 2002, O’Connell returned to her waterhole to test her idea. She had previously recorded the alarm call of local elephants that were being threatened by lions. The original call was audible, but O’Connell transformed it into a mostly seismic signal by cutting off the higher frequencies and playing it through shakers buried in the ground. When she did this, entire herds would freeze. They’d fall silent, become wary, and bunch up into defensive formations. Watching them through night-vision goggles, O’Connell was thrilled……”Elephants were detecting and responding to our seismic cues.”

A few years later, she repeated the experiment, but with an extra anti-predator rumble recorded in Kenya. This time, the Etosha elephants responded to the vibrations of the familiar local alarm, but not to the unfamiliar Kenyan one. They not only paid attention to vibrations but could tell if they were coming from elephants they knew.

4. PROTECTING THE SENSORY WORLD:

A better understanding of the senses can show us how we’re defiling the natural world. It can also point to ways of saving it. In 2016, marine biologist Tim Gordon traveled to Australia’s Great Barrier Reef to begin his PhD work. He should have spent months swimming among the corals’ vivid splendor. Instead, “I watched in horror as my study site got completely obliterated,” he tells me. A heat wave forced the corals to expel the symbiotic algae that give them nutrients and colors. Without these partners, the corals starved and whitened in the worst bleaching on record, and the first of several to come. Snorkeling through the rubble, Gordon found that the reefs had been not only bleached but Las o silenced. Snapping shrimps no longer snapped. Parrotfish no longer crunched. Those sounds normally help guide baby fish back to the reef after their first vulnerable months out at sea. Soundless reefs were much less attractive. Gordon feared that if fish avoided the degraded reefs, the seaweed they normally eat would run amok, overgrowing the bleached corals and preventing them from rebounding. But in 2017, “We went back and thought: Can we flip that on its head?”

He and his colleagues set up loud speakers that continuously played recordings of healthy reefs over the patches of rubble. The team would dive every few days to survey the local animals. “And on day 30,” Gordon says, “I remember moseying around with my dive buddies and saying, “There’s a big pattern here, isn’t there?” After forty days, he ran the numbers and saw that the acoustically enriched reefs had twice as many fish as silent one and 50 percent more species. They had not only been attracted by the sounds but stayed to form a community. “It was a lovely experiment to do,” Gordon says. It showed what conservationists can accomplish by “Seeing the world through the perceptions of the animals you’re trying to protect.”

Realistically, this is a small-scale solution : Loud speakers are expensive and coral reefs are big. Without reducing carbon emissions and forestalling climate change, reefs are in a a grim future, no matter how attractive they sound. Still, with half the Great Barrier Reef already dead, corals need all the help they can get. Restoring their natural sounds might give them a fighting chance and make the task of saving them a little less Herculean.

In 1995, environmental historian, William Cronin wrote that “the time has come to rethink wilderness.” In a searing essay, he argued that the concept of wilderness, especially as perceived in the United States, has become unjustly synonymous with grandeur….

“Idealizing a distant wilderness too often means not idealizing the environment in which we actually live, the landscape that for better or worse we call home.”

The majesty of nature is not restricted to canyons and mountains. It can be found in the wilds of perception - the sensory places that lie outside our Umwelt and within those of other animals. To perceive the world through other senses is to find splendor in familiarity, and the sacred in the mundane. Wonders exist in a backyard garden, where bees take the measure of a flower’s electric fields, leafhoppers send vibrational melodies through the stems of plants, and birds behold the hidden palettes or purples and grurples. In writing this book, I have found the sublime while confined to my home by a pandemic, watching tetra chromatic starlings gathering in the trees outside and playing sniffing games with my dog, Typo. Wilderness is not distant. We are continually immersed in it. It is there for us to imagine, to savor, and to protect.