How Animal Senses Reveal the Hidden Realms Around Us
By Ed Yong
Find it on Bookshop
We, as humans, interact with the world mostly through our vision, which is relatively good. We see the world, literally, as visible light. Other animals, however, have biases toward other senses. They may “see” the world as electric or magnetic fields, or as echoes, or as scents wafting through the air.
An Immense World is a beautiful exploration of what life is like for other animals. Whether it’s a dog sniffing the ground, or a seal twitching its whiskers, or a lost lobster heading home, Ed Yong gets inside their heads to understand how they perceive the world.
With beautiful language and apt metaphors, Ed Yong takes the reader on a sensory journey across air, land, and sea. He draws on sources that range from merely anecdotal to the most cutting edge research.
I bought this book before reading it because I have that much faith in Ed Yong. Unsurprisingly, he knocked it out of the park. I specifically bought the UK edition (cover shown here) because I love the cover art so much more than the US one. If you look closely you can see the author’s corgi, Typo, near the top of the illustration. This edition also has beautiful color photo inserts depicting animals discussed in each chapter. I raved about this book to my biologist friends, who are now all excited to borrow it from me when I’m done.
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 unique sensory bubble, perceiving but a tiny sliver of an immense world.
A Sensory Buffet
Ed Yong covers all the usual senses present in our immense world, and also a few you probably don’t often think about. With a chapter dedicated to each, the reader gets a taste of different types of sensory worlds. Yong describes:
- smells and tastes (Yes, together. They’re that strongly related)
- contact and flow (”We only have a rough sense of the sense that senses roughness.”
- surface vibrations
- echoes (Note this is different from sound)
- electric fields
- magnetic fields
Yong presents these senses in the context of Umwelt— the German word for environment, used to refer to the part of an animal’s surroundings that it can sense. A human’s Umwelt is predominantly visual. We rely very strongly on our eyes to tell us what’s going on around us. Even people who are blind from birth use visual words to desribe a world they have never seen, because that it the culture they’ve grown up in. A dog, on the other hand, has good vision but interacts more strongly with scents.
Nothing can sense everything, and nothing needs to. That is why Umwelten exist at all. It is also why the act of contemplating the Umwelt of another creature is so deeply human and so utterly profound. Our senses filter in what we need. We must choose to learn about the rest.
Here are some of my favorite examples and fun facts from the book. Apologies for the bias towards the ocean examples, but they’re just so fascinating.
Dogs’ noses are shaped in such a way that they can smell even when they’re exhaling. Humans, on the other hand, can only smell in one direction: when inhaling.
If a dog is sniffing a patch of ground, you might imagine that every exhalation would blow odorants on the surface away from the nose. But that’s not what happens. The next time you look at a dog’s nose, notice that the front-facing holes taper off into side-facing slits. When the animal exhales while sniffing, air exits through those slits and creates rotating vortices that waft fresh odors into the nose. Even when breathing out, a dog is still sucking air in.
A hallmark of a coral reef for humans is the bright color palette. Fish and coral stand out to us with their blues and yellows. But it turns out that to the fish themselves, they are completely camouflaged. This is because red light is absorbed by water, so even though fish have the same type of vision as humans, they are more sensitive to the blue end of the spectrum. To them, yellow blends in with corals, and blue blends in with the water, hiding them from potential predators.
Did you know that harbor seals’ whiskers are extremely sensitive? They can detect the difference between a light current and the wake of a fish passing by. They hunt by floating still, hiding among the fronds of a kelp forest, waiting to sense prey using their “radar dish of erect whiskers”.
Whale songs have been detected 1,500 miles away from their source (”He could listen to whales singing in Ireland with a microphone situated off Bermuda.”). For most people, that’s a mind-blowing fact. Naval analysts, however, hear these songs regularly. For them, whale songs are just a part of the workday. They are marked and ignored as irrelevant.
Bats using echolocation detected sound waves bouncing off surfaces with a change in density. When they’re flying around, sound bounces off bugs and potential obstacles. For dolphins, which ecolocate underwater, sound waves don’t bounce off the flesh of their prey, because its density is similar to that of water. Instead, the sound bounces off the bones and air pockets inside the prey. So if you’re ever in the water with a dolphin, remember that they can “see” inside of you. I didn’t need another reason to think dolphins are creepy, but there it is.
I have nothing to add to Yong’s evocative description:
Just as sighted people create images of the world from patterns of light shining onto their retinas, an electric fish creates electric images of its surroundings from patterns of voltage dancing across its skin. Conductors shine brightly upon it. Insulators cast electric shadows.
At the time of writing, magnetoreception remains the only sense without a known sensor. Magnetoreceptors are “the holy grail of sensory biology,” Eric Warrant tells me. “There may even be a Nobel Prize in finding them.”
Many animals use magnetic maps to find their homes. This is how sea turtles find their home beach to nest, and how salmon find their home stream to spawn. Even invertebrates do this: Caribbean spiny lobsters live in dens, but roam relatively far away to find food, and are always able to return home. How they do this isn’t well-understood but it is impressive:
Lohmann demonstrated this by capturing lobsters in the Florida Keys, driving them to a marine lab 23 miles away, and doing everything possible to confuse them along the way. He covered their eyes and sealed them in dark plastic containers. He hung swinging magnets above them. He even drove erratically. And yet, once the lobsters were released, they walked off in the exact direction that would take them home.
Implications for Conservation
I hope by now that Ed Yong has blown your mind and gifted you respect for the incredible sensory worlds in Earth’s animal kingdom. So what should you do with this newfound knowledge and passion?
The biggest threat to these Umwelten is sensory pollution. Ship noise disrupts whale communication. City lights disorient baby turtles. The world that humans have created is disrupting the natural one. We need to do what we can to reduce our interruptions.
Sensory pollution is the pollution of disconnection. It detaches us from the cosmos. It drowns out the stimuli that link animals to their surroundings and to each other. In making the planet brighter and louder, we have also fragmented it. While razing rainforests and bleaching coral reefs, we have also endangered sensory environments. That must now change. We have to save the quiet, and preserve the dark.
Remember there are more than five senses. According to the structure of this book, there are actually eleven. Each is unique and fascinating, and portrays the same immense world in a completely different light.
Humans don’t experience these sensory world like other animals do. To understand their perspectives, we need to make an effort, conducting experiments and collecting data. Every day we learn a little more about the Umwelten around us. With this knowledge, it is our duty to protect them.
Want to read more? Find An Immense World here: Bookshop
This book made it onto my list of the Top 10 Best Books of 2022! See the full list here.
The quotes above were gathered using Readwise. It’s a truly amazing app to help you remember what you read. If you want to try it out, use my link and we both get a free month 🙂
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The Nature of Nature: Why We Need the Wild by Enric Sala
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