How Do Dogs See in Total Darkness?
How Do Dogs See in Total Darkness?
Dogs are able to see in dim light thanks to special adaptations that allow them to make the most of low-light situations.
Their retinas contain photoreceptors, or light-sensitive cells, in both rod and cone form. These cells convert light into electrical signals that are sent to the dog’s brain, which controls their vision.
Pupils
The way your eyes see is through light-sensing cells called photoreceptors in the retina. These cells convert light into electrical signals that are sent to your brain.
There are two kinds of photoreceptors in your eye: cones and rods. Both are important for seeing in bright light, but rods work better in low-light conditions because they’re more sensitive to changes in brightness.
In dimmer light, cones adapt quickly while rods take a little longer. Dogs’ retinas have a higher number of rods than humans, which helps them see in low-light environments.
In addition, dogs’ pupils expand more than human pupils to let in more light. This also improves their night vision.
Retina
The retina is a layer of light-sensitive tissue that lines the inside surface of the back of the eye. It receives light that the lens has focused, processes it and sends it to the brain for visual recognition.
The rods in the retina work in tandem with cones to convert light into electrical signals that the brain unscrambles into pictures. These are the photoreceptor cells that allow you to see in dark rooms, distinguish different colors and navigate in low-light conditions.
Humans have a small number of photoreceptors, while dogs have much more. This allows them to detect shapes and movements better during the night, when most of their light-sensitive rods are active.
This ability to see in darkness comes from the fact that dogs have a special tissue behind their retina called the tapetum lucidum. It works like a mirror, reflecting light rays into the retina and boosting their vision. This is why you may notice their eyes have a glow when taking a flash photo.
Tapetum Lucidum
When light hits an animal's eyes, a reflective membrane called the tapetum lucidum bounces it back off the retina and creates a "second chance" for photons to be absorbed. This increases animals' ability to see in low light situations.
Tapetum lucidum is found in vertebrates such as teleosts, crocodiles and marsupials. It is also present in a number of carnivores, and some herbivores.
Tapetum lucidum is a type of eye iridescence that gives some species' eyes a glow, or shine, when light hits them. The color of this iridescence can range from blue, green, yellow or red depending on the angle at which the light is shining on the animal's eye and its mineral content.
In some animals, such as reindeer, this iridescence changes color. In winter, it takes on a decidedly bluish sheen. This is a natural adaptation to help them see during a time of year when they are not as well lit.
Light Sensitivity
Dogs have many adaptations that allow them to see better in dimmer light than humans do. These include a larger pupil, more light-sensitive cells in the retina and a camera lens closer to the retina.
Retinas are light sensitive structures located in the back of the eyeball. They contain two types of light-sensitive cells: rods and cones.
Cones provide color perception and detailed sight, while rods help detect motion and vision in dimmer light.
While dogs' retinas contain fewer cones than human eyes, they have more of the light-sensitive cells called rods. These cells work best in dimmer light and are also closer to the lens, making images on the retina brighter.
Another way a dog can see in the dark is by using something they have that humans do not: a reflective tissue behind the retina, known as the tapetum lucidum. This tissue acts like a mirror and makes the eye glow green when light shines on it.
