Crickets Have Ears On Their Knees

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Book Review: “An Immense World: How Animal Senses Reveal the Hidden Realms Around Us”

Author: Ed Yong

Reviewer: MARILYN FREEMAN

In Jewish teaching there is a concept of Tikkun Olam. It means “to heal the world.” But how do humans go about doing this when we understand so little of how the world works according to the other creatures that exist in it?

For example, did you know that ears exist on the knees of crickets? Or that some butterflies have ears on their wings which are tuned to the same frequencies produced by predatory birds? Or that Orb Weaver spiders produce silk that can transmit vibrations over a wider range of speeds than any known material? And those strands can be individually tuned!

If any of these facts grab your attention, then Ed Yong’s An Immense World is a book you’ll want to own and return to over and over. Some pages will make you laugh out loud. This is not something you’d expect in a science book.

Structurally, Yong divides senses into separate sections that include smells/tastes, light, colour, pain, heat, vibrations, electrical fields, magnetic fields and ending with why preserving quiet and dark “sensescapes” are threatened and need to be protected.

He starts with a German word Umwelt meaning the sensory bubble/environment in which each being lives. Defined and popularized in 1909, it refers to the perceptual world. Although the Umwelt of each species is limited, it doesn’t feel that way because it’s the only thing that’s known. Humans can’t detect the magnetic fields available to robins and sea turtles. We can’t trace the invisible trail of a swimming fish the way a seal can. Even when animals share the same senses with humans, their Umwelten can be very different.

Using humour and fascinating examples, Yong introduces readers to these Umwelten. Humans have trichromatic vision which can be pictured as a triangle representing red, blue and green cones. Every colour we see is a mix of those and can be plotted within that triangular space. A bird’s colour vision is a pyramid with the four corners representing each of its four cones. The entire human colour vision is only ONE face of that pyramid which makes it mind-blowing to think of all the colours that could be plotted within that pyramidical space!

Ticks are known for sucking blood but their heat sensors are found on the tips of their first pair of legs. When they wave these legs around questing, it looks like they’re trying to grab something but they’re also sensing. They can detect body heat up to 13 feet away. DEET and citronella don’t disrupt their sense of smell but they DO stop them from tracking heat!

Life exists in a planetary electric field. Even on a calm, sunny day the air carries a voltage of 100 volts for every meter off the ground. Flowers, being mostly water, bear the same negative electrical charge as their soil. Bees build up positive charges when they fly. Positively charged bees cause negatively charged pollen grains to LEAP onto their legs – even before they land! And the bees understand this!

While author Jong says that humans are closer than ever to understanding what it’s like to be another animal, we’ve made it harder than ever for other animals to exist. “Senses that served their owners well for millions of years are now liabilities.” Some are adapting to the human made world, some even flourish and for some, adaptation is not possible. As well, the human Umwelt dictates what questions a scientist will ask. “A scientist’s explanations about other animals are dictated by the data she collects, which are influenced by the questions she asks, which are steered by her imagination, which is delimited by her senses.” The human Umwelt will necessarily shape how we apprehend other Umwelten. It will also shape how we will deal with the changes human activity has caused, how we will affect Tikkun Olam.

Overall, this is a remarkably well-researched and joyous book. A reader could become popular (or merely tolerated) by telling their buddies “Did you know….?


Author Ed Yong is an award-winning science writer on the staff of The Atlantic, where he won the Pulitzer Prize in Explanatory Reporting and the George Polk Award for Science Reporting. An Immense World won the 2023 Andrew Carnegie Medal for Excellence in Nonfiction.

Marilyn Freeman joined the Peterborough Field Naturalists as soon as she moved to Peterborough because she hopes that the more we learn about how other beings interact with the world, the more people will care about how their own activities affect the activities of all others. She’s just not sure anyone really wants to know why dogs have side-facing slits in their noses.

1 Comment

  1. Fascinating ‘flyover’ of a book that a slow reader like me will never get to.

    Who knew how constricted and small human sensate capacities are, or how expansive and varied are those of the natural world ?

    When our dog puts her nose to the wind, I have a dim awareness of how captive I am to my limited experiential capacity. And that’s just a miniscule part of it.

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