A bug called a treehopper communicates by creating vibrations through its abdomen. A dog’s olfactory sense is so acute that it can tell twins apart by their smell. Shore birds called red knots use their bills to feel prey under the sand. These are a few of the amazing sensory tales that Pulitzer Prize-winning author Ed Yong reveals in An Immense World.
More than a collection of animal facts, An Immense World encourages the reader to enter the world of the fellow creatures who inhabit the Earth. He begins by introducing the reader to the concept of Umwelt. This term was popularized by zoologist Jacob von Uexküll in 1909 to describe the way an organism perceives the world. While it comes from the German word for environment, Umwelt is more than just the creature’s surroundings; it’s how an organism senses or experiences the world. As Yong explains, “A tick, questing for mammalian blood, cares about body heat, the touch of hair, and the odor of butyric acid that emanates from skin. These three things constitute its Umwelt. Trees of green, red roses too, skies of blue, and clouds of white–these are not part of its wonderful world. The tick doesn’t willfully ignore them. It simply cannot sense them and doesn’t know they exist.”
It may seem odd to us as mammals that a tick doesn’t see or notice a tree, but think about the treehopper bug I mentioned earlier. Those vibrations that the treehopper creates from its abdomen are sending signals to other treehoppers around them, yet we are completely unaware as we wander through their jungle home. Those vibrations are simply not part of our Umwelt.
I really like this approach as an alternative to our usual anthropocentric way of thinking. For example, infrasound and ultrasound are common concept to us; we hear all the time about whales, dolphins, and bats using ultrasound. Ultrasound is defined as sound waves whose frequencies are above the range of human hearing; specifically, above 20 kHz. We think of animals communicating with ultrasound as having a special, secret world that is completely hidden from other creatures, when in fact the vast majority of animals can hear what we would consider ultrasound. Just because it isn’t part of our Umwelt doesn’t make it secret.
This book is filled with fascinating insights into the animal world and, perhaps a little sadly, dispels a few myths. Contrary to the popular Oatmeal cartoon, the mantis shrimp doesn’t see a “thermonuclear bomb of light and beauty.” In fact, in spite of its abundance of photoreceptors, the mantis shrimp has been shown in experiments to be an absolute failure at discriminating color. It’s now thought that mantis shrimp see color in a completely different way than mammals do–the photoreceptors are still sending signals to the brain, but the animal may not have any concept of color at all. It’s Umwelt is different.
While I absolutely recommend this book and feel confident that you will enjoy it, I do need to mention that it took me much longer to get through than I expected. The information can get very detailed (the info about the mantis shrimp, above, is a micro-Cliffs Notes version), and sometimes I felt my brain slogging. It’s beautifully written and has great things to say, so I encourage you to read it. Maybe give yourself some time between chapters and don’t try to down it in one gulp. An immense world is waiting for you.