Books & Literature

Bound to Please / Realms of Animal Senses, from Vision to Vibration and Beyond

By Tom Baker / Japan News Staff Writer

15:19 JST, January 30, 2023

You’re at a soiree, on the host’s balcony with a drink in your hand, watching bats flit through the twilight. A fellow guest tries to chat you up by remarking that bats use echolocation, a kind of sonar, to navigate and catch flying insects.

You might wonder why they’re telling you something that everybody knows. But if they recently read “An Immense World,” a book about animal senses by Pulitzer-winning science journalist Ed Yong, they might go on to tell you something new.

For instance, bats are among the loudest animals alive. Some shriek like sirens, at 138 decibels. Luckily, the sound is too high-pitched for you and your new friend to hear.

In fact, Yong writes, bats “must avoid deafening themselves with every scream. They do so by contracting the muscles of their middle ears in time with their calls. This desensitizes their hearing while they shout and restores it in time for the [less loud] echo.” And they send out pulses of sound with “vocal muscles that can contract up to 200 times a second — the fastest speeds of any mammalian muscle.”

Wait, don’t leave the balcony yet! “They also space their calls so that each goes out only after the echo from the preceding one has returned. The air between a big brown bat and its target is only ever filled by a call or an echo, and never both.”

That’s what a bat can do alone. But how do they keep from confusing each other on group flights, which may include millions of chittering members?

This conundrum, called the “cocktail party nightmare,” is not yet solved. But some theories are described.

“An Immense World” is aptly titled. Yong shows that seemingly familiar senses, like vision, can stretch beyond what humans experience. While most people can see millions of colors, birds can see hundreds of millions, including unimaginably exotic blends of every color you might have seen in a Crayola box with ultraviolet hues you’ve never seen at all.

The consequences of having or lacking particular senses are often surprising. A population of South American squirrel monkeys includes both “trichromats” with strong color vision and “dichromats” with weak color vision — and each has a survival advantage. “The trichromats are indeed better at finding brightly colored fruit, but the dichromats surpass them at finding insects disguised as leaves and sticks.”

Yong also writes about less-familiar senses, like the detection of vibrations and flows, described by some researchers as “touch at a distance.” A seal can use its whiskers to trace the “hydrodynamic wake,” an invisible trail of turbulence, left by a passing fish. One researcher says that a harbor seal might be able to track a herring from nearly two football fields away. The seal follows the fish’s exact zigzagging path through the water just like a snuffling hound might follow the zigzagging path of a rabbit through the woods.

The facts recounted in this review are a mere taste of what Yong reveals about the sensory worlds of birds and mammals. He also introduces heat-seeking snakes, magnetically sensitive sea turtles, electroreceptive platypuses, and mosquitos that taste your skin with their feet the moment they land.

“An Immense World” will fill your head with so many must-share facts that you too might turn into someone’s cocktail party nightmare — or perhaps a science lover’s dream date.