During the day, under natural light, our dogs' eyes usually show a very deep color that highlights their look. But when darkness comes, it's common for them to cast a different glow, with shades of green, yellow, or purple.
How many times have you taken a flash photo of your pet at night and her eyes looked kind of ghostly? Well, you should know that this is a very important adaptive capacity that your organism developed during its evolution. On our site we will explain better why dogs' eyes glow in the dark You can't miss it!
Knowing a little more about canine vision
What do you know about the dog's sense of sight? The faculty of vision is possible thanks to the interaction between the eye, the brain and light This rule applies to humans, dogs, cats and other animals. Light enters the eyes through the pupils, which are these small centralized black circles surrounded by the iris (the colored part). As its main function is to regulate the entry of light into the eye, its structure has the ability to easily enlarge and retract.
In the mechanism of vision, the pupil acts as a hole, allowing light to reach the lens (a kind of transparent lens of the eye). Light rays must cross the entire length of the eyeball to reach the retina.
The retina is an inner ocular surface that consists of a type of organic screen. In it, we find numerous nerve endings that are sensitive to light and can be shaped like rods or cones. These endings called " photoreceptors" detect points of light entering the pupil and send them to the brain.
The interpretation of these sets of light information gives rise to the images we see. If we want to speak in more practical terms, the eyes act in a very similar way to a modern photographic camera.
In human vision, about 90% of the light rays that enter through the pupil are wasted or lose intensity. In addition, many of them are not captured by the photoreceptors of the retina, since they affect the "blind" space between the nerve endings. This explains why our night vision is quite poor.
Dogs and cats naturally developed, during their evolution, a system to minimize the loss of light in their vision. Behind your photoreceptors, there is a surface called " tapetum lucidum " that acts like a mirror, reflecting light coming through your pupils. This allows them to have excellent night vision and is the main reason why dogs' eyes glow in the dark
In addition, most mammals (with the exception of humans and primates) have a vertically elongated pupil, making its opening and closing similar to that of window curtains. This allows more light to enter and better use of light rays at night or in dimly lit environments.
Why do dogs' eyes glow in the dark?
As we said before, the eyes of dogs have a reflective surface called the tapetum lucidum which is located between the retina and the optic nerve. This mirrored screen reflects light entering the eye through the pupils, allowing the rod and cone photoreceptors to better capture the scarce light available at night.
So, if dogs' eyes glow in the dark, it's because their vision is adapted to optimize the low incidence of light raysThey inherited this characteristic from their wolf ancestors, who should be able to hunt and defend their territory at night as well. His capabilities never cease to amaze us, right?
How do you explain the brightness of different colors?
Have you noticed that the eyes of each animal have a different color shine? Some dogs have a very reddish hue, while in others yellow or green tones predominate. This is explained by the concentration of riboflavin (an amino acid) or zinc (a metal) present in the cells that pigment the surface of the tapetum lucidum.
An animal's age and coat color also influence how well its eyes reflect outside light. Older dogs suffer from a reduction in the reflection potential of their eyes, as their ocular lenses thicken. This also explains why your vision becomes poorer over the years.
