 | An Immense World is a deep dive into how animals sense our world and it’s full of fascinating science. There are surprises in animal vision (birds see ultraviolet), touch (a manatee has thousands of sensitive whiskers all over its body), hearing (some spiders sense sound with their leg hairs), and more unusual sensations such as echolocation (bats), electrolocation (electric eels), and magnetoreception (migrating songbirds). As one scientist noted: “We don’t have to look to aliens from other planets. We have animals that have a completely different interpretation of what the world is right next to us.” |
TASTE
"The most extensive taste in nature surely belongs to catfish. These fish are swimming tongues. They have taste buds spread all over their scale-free bodies, from the tips of their whisker-like barbels to their tails.”
"The most extensive taste in nature surely belongs to catfish. These fish are swimming tongues. They have taste buds spread all over their scale-free bodies, from the tips of their whisker-like barbels to their tails.”
SIGHT
"Many birds of prey, like eagles, falcons, and vultures, actually have two acute zones in each eye—one that looks forward, and another that looks out at a 45-degree angle.
"A cow can simultaneously see a farmer approaching it from the front, a collie walking up from behind, and the herdmates at its side.
"Through a fly’s eyes, the world might seem to move in slow motion. The imperceptibly fast movements of other flies would slow to a perceptible crawl [and] slow animals might not seem like they were moving at all.
"Many birds of prey, like eagles, falcons, and vultures, actually have two acute zones in each eye—one that looks forward, and another that looks out at a 45-degree angle.
"A cow can simultaneously see a farmer approaching it from the front, a collie walking up from behind, and the herdmates at its side.
"Through a fly’s eyes, the world might seem to move in slow motion. The imperceptibly fast movements of other flies would slow to a perceptible crawl [and] slow animals might not seem like they were moving at all.
 | "…since red light is strongly absorbed by water, [fish eye] sensitivities shifted toward the blue end of the spectrum. This explains why so many reef fish, like the blue tang that stars in Pixar’s Finding Dory, are blue and yellow… Their colors look incredibly conspicuous to snorkeling humans… But the fish themselves are beautifully camouflaged to each other, and to predators." |
TOUCH
"Manatees are the only known mammals that only have vibrissae and no other kinds of hair. Aside from the whiskers on their [prehensile snout], they have another 3,000 scattered all over their large bodies….Manatees use these body-wide whiskers…to sense the water flowing around them."
"Manatees are the only known mammals that only have vibrissae and no other kinds of hair. Aside from the whiskers on their [prehensile snout], they have another 3,000 scattered all over their large bodies….Manatees use these body-wide whiskers…to sense the water flowing around them."
 | "As a fish swims, it leaves behind a hydrodynamic wake—a trail of swirling water that continues to whirl long after the animal has passed. Seals, with their sensitive whiskers, can detect and interpret these trails… from up to almost 200 yards away." |
"The lateral line is found in all fish (and some amphibians). … A swimming fish displaces the water in front of it, creating a flow field that envelops its body. Obstacles distort that field, and the lateral line can detect those distortions, providing the fish with a hydrodynamic awareness of its surroundings…. Schooling fish use their lateral lines to match the speed and direction of their nearest neighbors. "
VIBRATION
Plants are strong, flexible, and springy, which makes them fantastic carriers of surface waves. Insects exploit that property, filling plants with their vibrational songs. Between treehoppers, leafhoppers, cicadas, crickets, katydids, and more…around 200,000 species of insects communicate through surface vibrations. Their songs normally aren’t audible [to us], and so most people are completely unaware that they exist.
Plants are strong, flexible, and springy, which makes them fantastic carriers of surface waves. Insects exploit that property, filling plants with their vibrational songs. Between treehoppers, leafhoppers, cicadas, crickets, katydids, and more…around 200,000 species of insects communicate through surface vibrations. Their songs normally aren’t audible [to us], and so most people are completely unaware that they exist.
 | "Cats…have a lot of vibration-sensitive mechanoreceptors in the muscles of their bellies. When a cat crouches down during a stalk, is it doing more than lying low? Is it also sensing the vibrations of potential prey? Could a lion pinpoint distant antelope herds?" “The lying about that nature documentaries attribute to the innate laziness of lions may actually be a period of astute assessment.” |
SOUND
"Ears exist on the knees of crickets and katydids, the abdomens of locusts and cicadas, and the mouths of hawkmoths. Mosquitoes hear with their antennae. Monarch caterpillars hear with a pair of hairs on their midsection. The bladder grasshopper has six pairs of ears running down its midsection, while mantises have a single cyclopean ear in the middle of their chests.
"African elephants use infrasound just like their Asian counterparts—and in every conceivable context. There are contact rumbles that help individuals find each other. There are greeting rumbles they make when reuniting after a separation. Males make rumbles when in heat, and females make rumbles in response to them. [These deep sounds are] mostly imperceptible to us [but] detected by other elephants over long range.
"[Ultrasound] refers to sound waves with frequencies higher than 20 kHz, which marks the upper limit of the average human ear [but] Even our closest relatives, chimpanzees, can hear close to 30 kHz. A dog can hear 45 kHz; a cat, 85 kHz; a mouse, 100 kHz"
"Ears exist on the knees of crickets and katydids, the abdomens of locusts and cicadas, and the mouths of hawkmoths. Mosquitoes hear with their antennae. Monarch caterpillars hear with a pair of hairs on their midsection. The bladder grasshopper has six pairs of ears running down its midsection, while mantises have a single cyclopean ear in the middle of their chests.
"African elephants use infrasound just like their Asian counterparts—and in every conceivable context. There are contact rumbles that help individuals find each other. There are greeting rumbles they make when reuniting after a separation. Males make rumbles when in heat, and females make rumbles in response to them. [These deep sounds are] mostly imperceptible to us [but] detected by other elephants over long range.
"[Ultrasound] refers to sound waves with frequencies higher than 20 kHz, which marks the upper limit of the average human ear [but] Even our closest relatives, chimpanzees, can hear close to 30 kHz. A dog can hear 45 kHz; a cat, 85 kHz; a mouse, 100 kHz"
 | "An owl’s ears are uniquely asymmetrical, with the left being higher than the right…If a sound comes from above or from the left, it arrives a little sooner and little more loudly at the higher left ear than the lower right one…. The owl’s brain uses these differences in timing and loudness to work out the position of the sound’s source in both the vertical and the horizontal." |
ECHOLOCATION
"[A bat unleashes] a stream of short, ultrasonic pulses from her mouth. By listening for the returning echoes, she can detect and locate objects around her—a form of biological sonar. Only a few animals have this skill, and only two groups have perfected it: toothed whales (like dolphins, orcas, and sperm whales) and bats.
While bats can only sense the outer shapes and textures of their targets, dolphins can peer inside theirs. If a dolphin echolocates you, it will perceive your lungs and your skeleton…. It can pick out the air-filled swim bladders that allow fish, their main prey, to control their buoyancy [like an] X-ray machine or an MRI scanner."
"[A bat unleashes] a stream of short, ultrasonic pulses from her mouth. By listening for the returning echoes, she can detect and locate objects around her—a form of biological sonar. Only a few animals have this skill, and only two groups have perfected it: toothed whales (like dolphins, orcas, and sperm whales) and bats.
While bats can only sense the outer shapes and textures of their targets, dolphins can peer inside theirs. If a dolphin echolocates you, it will perceive your lungs and your skeleton…. It can pick out the air-filled swim bladders that allow fish, their main prey, to control their buoyancy [like an] X-ray machine or an MRI scanner."
ELECTROLOCATION
"After 160 years of research, it is clear that the knifefishes and elephantfishes use their electric fields to sense their surroundings, and even to communicate with each other. Electricity is to them what echoes are to bats, smells are to dogs, and light is to humans—the core of their [sensory worlds]."
In addition to sensation, these fish use electricity to hunt: "The most powerful of the three electric eel species can discharge 860 volts—enough to incapacitate a horse."
"After 160 years of research, it is clear that the knifefishes and elephantfishes use their electric fields to sense their surroundings, and even to communicate with each other. Electricity is to them what echoes are to bats, smells are to dogs, and light is to humans—the core of their [sensory worlds]."
In addition to sensation, these fish use electricity to hunt: "The most powerful of the three electric eel species can discharge 860 volts—enough to incapacitate a horse."
MAGNETORECEPTION
"…sea turtles, spiny lobsters, songbirds and many others [can sense the planet's magnetic field]. Their ability, known as magnetoreception, allows them to navigate even when celestial bodies are obscured by clouds or darkness, when large land masses are wreathed in fog or murk, and when the skies and oceans are devoid of telltale scents."
"…sea turtles, spiny lobsters, songbirds and many others [can sense the planet's magnetic field]. Their ability, known as magnetoreception, allows them to navigate even when celestial bodies are obscured by clouds or darkness, when large land masses are wreathed in fog or murk, and when the skies and oceans are devoid of telltale scents."
It’s impossible to capture the variety and wonder of the fascinating universes revealed by An Immense World. Ed Yong is a fabulous writer and sinner of the Pulitzer Prize. For more on just two of the animals explored in this incredible book, see Human Hunters and Alien Brains.
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