Meet the creatures with the most powerful, sensitive, weird, and sophisticated eyes, ears, and noses in the animal kingdom.
Humans are pretty cool, and we have some unique strengths compared to other animals. There’s our hallmark intelligence that has led to world domination and geniuses from Isaac Newton to Cardi B. We have unique abilities with language, and our skills have uniquely enabled cooperation and technology to compound at exponential rates over generations. We’re also the only animals that blush.
That’s some cool shit, but other animals surpass us at almost everything else we do. Let’s meet them!
Eyes are thought to have evolved at least 40 times independently, and there’s a spectacular array of eye designs in the animal kingdom. The many aspects of vision (including visual acuity, light wavelengths that can be detected, low light sensitivity, ability to detect motion/objects, depth perception, color discrimination, and field of view) mean it isn’t possible to definitively rank animals’ eyesight, but there are certainly some dope animals that far surpass us in various aspects.
The Human Standard
Although there are some things we don’t have (like night vision, ability to see UV light, ability to see well underwater, and super-wide field of view), humans actually see pretty damn well compared to the broader animal kingdom. We have the best daytime eyesight of all mammals, and in fact, you could even make a case that in good daylight and when looking ahead, we have the best general vision of any animal. Not bad, humans!
For visual acuity, we measure normal human vision (20/20) based on the clarity/sharpness you should see when standing 20 feet away from an eye chart. 20/40 means you need to be 20 feet away to make out what others can see at 40 feet, and 20/15 means your vision is so good that at 20 feet you see fine details that other people need to be 15 feet away to make out. 20/10 is thought to be the maximum acuity of human eyes.
The Animal Champions
Visual acuity: Eagles, hawks, and falcons can see the furthest during the daytime, easily beating human visual acuity. Although there isn’t a lot of precise data distinguishing visual acuity between particular species, eagles and hawks are thought to have the sharpest vision in the animal kingdom and some species have the equivalent of 20/2 eyesight, which means they can see up to 10 times as far as humans can. They also see more colors than us, including colors in the UV spectrum.
Night vision: Cats and owls are famous as night vision champs. But are they the best? Not by a long shot. For comparison, we can use lux, a measure of light per square meter. Bright sunlight is well over 10,000 lux, but human eyes can operate with as little as 1 lux. Domestic cats can see in just 0.125 lux, or one-eighth the light we need. Owls can do maybe 10 times better than that. Tarsiers need only 0.001 lux, and dung beetles take it down to 0.001–0.0001 lux. But for the ultimate night vision, a few stand out: The xylocopa tranquebarica species of carpenter bee needs only 0.000063 lux, enabling them to continue flying (a hard task), foraging, and seeing colors on moonless nights. The deep-sea gigantocypris is listed in some reports as the best of any animal at gathering light, though they see at low resolution. But the not-usually-admired American cockroach is likely the winner. Their sight has been measured in a different way, so I can’t directly compare them using lux, but they’re able to respond to light received by their eyes at less than one photon per second, making them essentially impossible to beat based on the laws of physics.
Most complicated eyes: Mantis shrimp have got this one in the bag. They have independently roaming eyes, three pupils per eye (giving each eye independent depth perception), and they can see ultraviolet, far-red, and polarized light. They use 12–16 different types of photoreceptor cells to see color, which compares to our three (for red, green, and blue) and is more than any other animal (although the bluebottle butterfly is up there with 15 types). You might think this means they can see dramatically more colors (the Oatmeal hypothesized their vision is a “thermonuclear bomb of light and beauty”), but in fact, they seem to do rather poorly in tests for distinguishing color. That’s only one of the reasons National Geographic describes their way of seeing as “absurdly over-engineered.”
360° field of view: Woodcocks, chameleons, dragonflies, and (depending on the position of their head) jumping spiders can pull this off. However, this vision isn’t perfect. E.g., less than 10° of a woodcock’s vision is binocular, which compares to humans’ 180° field of view with 140° being binocular. Dragonflies’ fancy eyesight also comes at a cost: nearly 80% of their brains are dedicated to vision.
Largest eyes: The colossal squid is the winner for any living animal. Their eyes can reach up to an eye-popping 30 centimeters in diameter, significantly larger than a regulation soccer ball (22 cm).
Cyclopses: All species within the Cyclops genus of copepods have one eye. They’re the only animals like that if you exclude birth defects and microorganisms with eyespots. Fun fact: The one-eyed character Plankton from SpongeBob SquarePants is a copepod.
Every animal has a specific range of frequencies it can hear and is most sensitive to sounds in particular parts of its range. We use Hertz (Hz) for measuring pitch and decibels (dB, a logarithmic measure) for loudness.
The Human Standard
Humans have a decent pitch range, from about 20 Hz to 20,000 Hz. We call frequencies below the range of human hearing infrasonic and call frequencies above our range ultrasonic. The lower limit of audibility for humans is 0 dB.
Prolonged exposure to infrasound at high volumes can make us sick, rupture our organs, and even kill us, despite being completely silent to our ears.
The Animal Champions
Lots of animals can hear infrasonic and ultrasonic sounds beyond our capabilities. This includes most of our pets. Cats, dogs, rabbits, and guinea pigs can all hear wider ranges of pitch than us.
But which animals have the best hearing?
Highest frequency: The greater wax moth has the best ultrasonic hearing in the world by far, going up to at least 300,000 Hz. It also hears the widest range of frequencies, and its hearing is highly precise (e.g., it can distinguish between bat calls and equally high-frequency mating calls from other greater wax moths).
If you’re wondering why a moth needs such astonishing hearing, the answer is at least in part that these moths are often eaten by bats that produce incredibly high-pitched calls. So their hearing has stayed several steps ahead. There’s no sound any bat can make that this moth can’t hear.
Lowest frequency: Pigeons’ ability to hear extremely low-frequency infrasounds (as low as just 0.05 Hz) is second to none. They can use this superpower to detect distant storms, but at such low frequencies, they can even detect upcoming earthquakes and volcanos.
Most acute hearing: Wolves, cats, and some breeds of dogs have the most far-out long-distance hearing. All of them are among animals that can rotate their ears to better capture sound, and all of them have been known to detect sounds as quiet as a ridiculous -15 dB (in the frequency ranges they’re most sensitive to). For comparison, most anechoic chambers (rooms designed to completely absorb sound reflections) can’t reach that low of a volume.
Then there are the incredible animals that can use echolocation, in which hearing plays a part. But I’m going to treat that as a separate sense and cover it in another post.
For comparing smell, some metrics people look at are the number of olfactory receptors (ORs) an animal has, the number of functional OR genes in its DNA, and the size of the olfactory bulbs in its brain. Although cross-species comparisons of these things are not always good predictors of superior smell, this study did find a positive correlation across species for the number of OR genes an animal has and its ability to discriminate subtly different odors.
We can also look at things like the presence of specialized smelling equipment (e.g., a Jacobson’s organ) and observed behavior such as how many miles an animal has been known to follow a scent.
The Human Standard
Compared to many animals, humans have fewer OR genes, fewer scent receptors in our noses, less of our brains are dedicated to smell, our Jacobson’s organs are vestigial (preventing us from detecting pheromones), and smell just doesn’t play as central a role in our lives.
But while there’s no doubt that the sniffers on some animals outperform us, we might be underestimating ourselves. It turns out that humans can be trained to follow a scent trail, thanks in part to our stereo smell and as evidenced by my girlfriend’s ability to sniff out the location of any McDonald’s. There are also some scents we’re particularly sensitive to. For example, we’re better than dogs at smelling some fruits and flowers, and better than mice at detecting human blood.
The Animal Champions
You can find lots of articles online telling you how many thousands of times better dogs or bears are at smelling than humans, but it seems there hasn’t been a lot of science to back up those conjectures. However, we do know that many animals live in a different world of smell compared to us. A world where even when you can’t see or hear anyone around you, you’re aware of the presence of everyone nearby and others who were there before you.
But which animals do we think have the best noses in the world? Two candidates stand out: elephants and bears.
A team of Japanese researchers studying olfactory receptor (OR) genes found that elephants have the most documented in any animal so far. African elephant genomes contain nearly 2,000 functional OR genes—five times more than humans and more than twice as many as dogs. Although the study didn’t examine the function of each gene, the huge number of smell-related genes strongly suggests those long trunks contain powerful and sensitive smelling abilities.
Elephant behavior backs this up. Both African and Asian elephants are particularly good at smelling water, which they can detect up to 12 miles (nearly 20 km) away. A 2007 study even found that African elephants can distinguish between members of two tribes in Kenya (only one of which hunts elephants) based on smell.
Bears are well known for their uncanny ability to smell food over long distances, and silvertip grizzlies and polar bears are often described as having particularly strong senses of smell. There are lots of stories about bears being able to smell animal carcasses from miles away (some say up to 20 miles or 32 km), and male polar bears have been known to trek 100 miles (160 km) following the scent of a sexually receptive female.
These claims should probably be taken with a grain of salt since there’s been little research actually quantifying bears’ sense of smell, but what we know about their biology backs up that they’re in a league with the world’s best. For example, bears have highly developed snouts containing hundreds of tiny and highly dexterous muscles, their snouts are estimated to contain more scent receptors than bloodhounds (who are certainly no slouches in the smell Olympics), and they have massive olfactory bulbs (five times the size of ours, despite their brains being only one third as large).
Professional smellers: Dogs don’t quite make the list of champions, but they’re still ridiculously good sniffers and they’re a lot easier to train than bears. Dogs are employed to sniff out explosives, missing people, and even cancer. Among dog breeds, bloodhounds stand out as the best. They’re sometimes referred to as a nose attached to a dog, and for good reason, since they have more scent receptors in their noses (up to 300 million) than any other breed. That compares to 5–6 million for humans. Bloodhounds have been known to follow scent trails for more than 100 miles and detect smells over two weeks old. They’re so reliable that the nosewitness testimony of a trained bloodhound is admissible in most US courts.
Dogs aren’t the only ones with noses put to work by humans. African giant pouched rats are used in Cambodia and at least a couple of African countries to sniff out land mines.
An olfactory myth: It’s commonly thought that sharks can smell a drop of blood from far away (some say a mile), but is it true? Apparently not. Researchers from Florida Atlantic University put shark smell to the test and found that although shark smell is impressive, it’s no better than a typical fish. A good article on the subject clarifies the myth: “sharks can smell a drop of blood in a volume of water about the size of a backyard swimming pool.”
In future posts, I’m hoping to explore the animal champions of taste, touch, memory, and superpowers we don’t have at all including echolocation, flight, generating electricity and light, detecting electric and magnetic fields, and color changing. I’ll also be covering the best animals in the world at a range of athletic skills, along with circus freaks of the animal kingdom.
If you find new and better research or have any corrections, I’d be happy to update the article so let me know.
Finally, special thanks to animal lover Meena Sengottuvelu who reviewed this article in advance and suggested many improvements.
What about mental senses? We don’t know whether animals have the same sort of visual, auditory, and olfactory imagination as humans, but did you know that these mental senses also work very differently for many humans? Learn more in my post on aphantasia and hyperphantasia.