The invisible spectrum: the colors that people can't see, but animals can.

Ultraviolet and infrared radiation, although imperceptible to the human eye, are essential for the survival of several species. National Geographic magazine explained the phenomenon.

The world is largely defined by colors. The blue hues of the sea or the vibrant greens of plants are part of our everyday sensory experience.

However, there are forms of light that the human eye cannot perceive. These "invisible" colors do not represent a visual impairment, but rather a biological characteristic: they are simply beyond the human vision spectrum.

 Both ultraviolet (UV) and infrared (IR) light are invisible to humans, although they are part of the electromagnetic spectrum.

 A world invisible to the human eye

The human eye only detects a limited range of the electromagnetic spectrum, between approximately 380 and 750 nanometers. Below this threshold lies ultraviolet light, and above it, infrared light.

These forms of light cannot be processed by the human retina due to the physical properties of photoreceptors, but they nonetheless have a presence or impact on the environment.

 Some animal species developed the ability to capture these wavelengths as an evolutionary adaptation. While they are invisible to humans, they represent fundamental visual tools for certain animals.

                                                                          

  

Ultraviolet Light: A Guide to Insects

Ultraviolet light has a shorter wavelength than violet, the most extreme color in the human visible spectrum. This form of radiation, although imperceptible, is present in the environment and has obvious effects such as sunburn.

Insects such as bees use ultraviolet light to locate flowers more precisely. Several plant species have patterns on their petals that glow brightly under this radiation. These patterns act as signals indicating where the nectar is.

In the case of butterflies, the use of this light allows them to distinguish between flowers that appear identical to the naked eye. Through ultraviolet patterns, they can identify which ones are more nutritious, which optimizes their foraging.

For butterflies, using this light allows them to distinguish between flowers that appear identical at first glance. Using ultraviolet patterns, they can identify which ones are most nutritious, which optimizes their foraging.

                                                                                

Infrared: The Thermal Language of Snakes

 At the opposite end of the visible spectrum is infrared light, with a wavelength longer than red. Although humans cannot see it, they can feel it as heat, as occurs when approaching a campfire.

 Certain species, such as snakes, have developed thermal sensors capable of detecting this radiation. Pythons and rattlesnakes use this ability to identify their prey in complete darkness, based solely on the body heat they emit. This detection system is key to their hunting strategy.

Something similar happens with certain vampire bats, which use infrared vision to locate the warmest areas on their prey's skin before feeding. This type of perception allows for more effective and precise contact.

 Human instruments to see the invisible

 Despite the natural limitations of human vision, technology has made it possible to access visual information outside the visible spectrum.

Devices such as infrared cameras or ultraviolet filters offer the ability to "see" invisible wavelengths, both in scientific contexts and in everyday applications.

These advances are used in disciplines such as astronomy, biology, and security, expanding perceptual capabilities beyond physical limits.

Physicist and researcher Javier Mariño Villadamigo explained that there are "instruments such as the Fermi telescope, which allows us to observe the light emitted by the cosmos at wavelengths as small as 0.01 nm, where we see super-energetic gamma rays."

He added: "On the other hand, we have the Very Large Array telescope, which "sees" at wavelengths of up to kilometers, capturing interstellar dust and gas."

The incorporation of these tools provided a new dimension to scientific observation, allowing the recording of natural phenomena that previously remained hidden from human view.

This expands knowledge about the environment and the different ways in which other species interact with it.