4 Ways Animals Sense a World Invisible to Humans

CC BY 2.0. Sabriamin M/Flickr

Humans think we get it all, but there's so much more than meets the eye.

Biologist Edward O. Wilson says that we sense less of the physical world around us than most people would ever know. “We live entirely within a microscopic section of the stimuli that are possible and that flood in on us all the time,” he notes. And indeed, when we look at the ways in which various animals use these natural stimuli to navigate and communicate, it’s really rather profound. We are surrounded by a whole world of sensations that are completely unknown to us.

Electromagnetic spectrum

We think we see everything – and how could we understand there is more if we can’t see it? But as Wilson points out, for example, in the Big Think video, Pheromones and Other Stimuli We Humans Don't Get (which you can watch below), we only see the electromagnetic radiation across a remarkably tiny section of the entire spectrum. Fom ultra low frequency radiation to gamma radiation – we only get a sliver of that. Other creatures get other parts of the spectrum. Pollinators like bees and butterflies have the ability to see ultraviolet, which helps them navigate into a flower’s sweet spot. Where we see a collection of yellow petals on a black-eyed Susan, a bee sees a bull's-eye pattern that tells the little lady exactly where to aim.

Meanwhile, pigeons – the bane of many an urban dweller (or, the delight of many of an urban dweller, depending on where you stand) – have a truly remarkable knack for discriminating between almost identical shades of color; we’re talking wavelength that differ by only a few billionths of a meter. As opposed to trichromacy, the triple system of our color perception, pigeons can sense as many as five different spectral bands.


A number of animals use echolocation to both navigate and hunt. Imagine if we were able to emit high-frequency sounds and use the returning echoes to form “images” of our environment. As if by singing, almost, we could see.

Also known as biosonar, this is a gift bestowed upon animals like bats, as you probably already know, but also toothed whales and dolphins, as well as (in simpler form) shrews and some cave-dwelling birds. But it doesn’t stop there, as Wilson explains, other organisms echolocate with electrical impulses. “They broadcast from their bodies like electric fish and electric eels,” Wilson says. “We have no sense of that whatsoever and yet bats, for example, can maneuver with fantastic speed and accuracy just using echo locations from their own voices.”

Magnetic fields

While science tells us all about Earth's magnetic field, a large number of animals can actually sense it, and they use it to their advantage all the time.

There have been a number of experiments showing that organisms from hamsters, salamanders, sparrows, and rainbow trout to spiny lobsters and bacteria employ the magnetic field. "I would go so far as to say that it's nearly ubiquitous," says John Phillips, a behavioral biologist who has seen this ability in everything from fruit flies to frogs.

Dogs use an internal magnetic compass to guide pooping orientation, salmon use it to navigate the ocean, and even cows tend to face either magnetic north or south when grazing or resting.

Sadly for us humans, there’s no scientific evidence that we have this “sixth” sense. We have GPS instead.


While humans live in a world mostly dominated by sight and sound, other organisms live an existence predicated on smell – specifically by means of pheromones. These chemical smells communicate everything from stress and alarm to danger and sexual fertility. Ants are the poster children for this phenomenon. According to Wilson, they have ten to 20 substances that they use to smell and taste in organizing their society. “We have no sense of that whatsoever, you know, no way of knowing what they're doing,“ he says. “We just see them running around; they look like they're little particles in movement or forming lines and so on. With those ten to 20 pheromones they use they can vary meaning greatly by how much of the pheromone they release ... it's almost like sentences being formed.” With pheromones, ants say: pay attention; come in this direction; a problem; a situation; opportunity; come; attack, attack, attack; step aside; help clean it; help clean it. “It just goes on forever,” says Wilson.

Bacteria, other social insects, and various mammals live in a sea of pheromones that we have little capacity to grasp.

“We live, all the time, especially in nature, in great clouds of pheromones,” says Wilson. “We're just beginning to understand how the natural world works. And a large part of it is that it lives in another world from the one we do, the pheromone world.”

See Wilson talk about the mysterious world invisible to us in the video below: