Three things about animal senses from Ed Yong's An Immense World: ttftw 2023w24

Three things from this week.

There’s a genre of book that excitedly catalogs gee-whiz factoids about the unbelievable activities going on in the animal world. Tigers that can leap 20 feet straight up and ants that lift 50 times their own body weight. Blue whales are the biggest, giraffes are the tallest, cheetahs are the fastest, and camels are the coolest. I loved learning these little bits of trivia when I was a kid. A world with all these different creatures in it felt so much bigger than the one I lived in day to day.

This week I want to tell three things from a book that’s helping me form a more grown-up and more complete perspective on the big world we share with all those whacky critters. Ed Yong explicitly spells out early on in An Immense World that understanding how a bat uses echo-location is not the same as imagining yourself, a human, with wings and an extra sense. Instead he goes to lengths to encourage deeper thinking about the world from the perspective of a creature with a very different set of senses and different ways to combine those senses to understand the world around it. He attempts to avoid simple comparisons of numerical measurements of resolution or frequency ranges. When these do appear they’re put into clear context. For example, to think about wider and narrower fields of vision, the reader is encouraged to look at your thumbnail with your arm outstretched. This covers about one degree of the circle around you. With a visualisation like this we’re better prepared to understand what it means that an owl can localize sound within two degrees. Beyond giving context and comparisons for numbers though, the writing encourages us to think about these senses interacting as multiple dimensions of an individual creature’s existence. While evolutionary advantages and selection are clearly relevant, each of these creatures makes its own way in the world, one by one.

In every conversation I’ve been having lately I find myself bringing up topics that came up recently from this book. So here are three things I’ve learned so far. They’re not really spoilers because my ability to explain here only goes as far as the factoid level; I can’t provide the context or depth that you’ll get from listening to the book.

Birds can smell, dogs aren’t colourblind, and surface waves are a great way to communicate.

Birds' eyes

Birds that appear white to us may also have colours mixed from the ultraviolet range. We (mostly¹) can’t see into ultraviolet but some birds and other creatures can. However they may or may not see the other primary colours we do. The picture they form also differs in visual acuity - humans generally see more detail in good light than a lot of other animals.

The view observed by birds like ducks or herons covers more of the sphere above or behind them than our stereo overlapping front-facing eyes. These are some of the ways that a bird can take in light differently from us.

It’s not easy to think like a creature other than the one you are. Ed mentions YouTube videos showing elaborate bird mating dances where the subject appears to turn away and ignore the performance. However, he observes, if your eyes are on the sides of your head then turning your head away can mean getting a better look at the performer.

Dogs noses

Dogs are continuously smelling. Not just always pulling in air and deciding what smells are sampled with that breath. Their noses are structured differently from ours - on the inside too. They keep some portion of the air inside and continuing to soak up whatever is floating around in it. This isn’t unique to dogs but it relies on structures that we probably don’t have.

Surface waves

Many animals seem to be able to create or perceive surface waves. Similar to the way that a spider feels a twinge on its web, other creatures can feel motion transmitted along some pretty coarse surfaces like sand or dirt. Treehoppers can vibrate the branch they’re on, sending out surface waves that others receive through their legs. Oh, and maybe elephants do something similar.

Finally, I also wanted to point out that I’m listening to this as an audiobook and that I’ve been very impressed with the timing, pacing, and performance of the reader. So I checked to see who read the audiobook edition and … also Ed Yong.

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