Octopuses are the eight-limbed mollusc of the order Octopoda that evolved 530 million years ago. In the past, many researchers believed that Octopuses were completely blind.
But that’s not true; in recent research, it has been proved that Octopuses can see as well as recognize various color shades. So, here the question arises, “What do Octopus see?“
Octopuses see the world only in black and white with the full range of vision without any blindspot. They possess only one kind of photoreceptor in their eyes that allows them to perceive only black and white colors. However, their differently shaped pupils enable them to detect color by creating colorful fringes around the objects, known as chromatic aberration, according to researchers from the University of California, Berkeley, and Harvard University.
Octopuses have advanced vision compared to humans, and they use different methods to sense the wavelength of various colors. They process different wavelengths and combine them in the optic nerve to form a colorized image. It is way complex. Later in this post, we have explained more in detail. So, let’s begin.
How and What do Octopuses see?
Octopuses have advanced vision, and it is difficult to explain how and what they see. But it is confirmed that their weirdly shaped pupils play a significant role in their vision.
We all know, Octopuses, squid, and other cephalopods are colorblind, having one kind of photoreceptor in their eyes that can only perceive black and white shades.
On the other hand, humans have three types of photoreceptors in our eyes; to detect small, medium, and large wavelength colors, i.e., blue, green, and red hues. And with the help of these three kinds of cones, we can recognize millions of color shades of the visible spectrum.
However, octopuses have pupils to mimic the colors of backgrounds. According to UC Berkeley graduate student Alexander Stubbs, octopuses and other cephalopods may be able to see colors but differently from humans or any other animal.
It is assumed that they have evolved their vision to focus on wavelengths using an entirely different method. And in this method, their weirdly shaped pupils play the primary role.
Cephalopods have unusual pupils- U-shaped, W-shaped, or dumbbell-shaped. These pupils force light to enter the eye from different directions simultaneously, making everything hazy but creating colorful fringes around objects, known as chromatic aberration.
They have the ability to bring specific wavelength focus to the retina, and in this way, they recognize colors. That’s why octopuses change colors to hide from predators, attract their partners, or find their foods.
On the contrary, humans have round pupils, and the light enters straight into the retina, giving us sharp vision with color depth. Our eye structure is simple as many other common animals.
In addition, Octopuses can see lights with their arms even in the complete darkness. Researchers noticed that during an experiment, when the arms of the octopus sense light, it quickly pulls them towards their body.
Their skin is covered in pigment-filled organs called chromatophores that can easily recognize light and reflexively changes the color during the exposure. It helps octopuses hide from predators by using camouflage and navigating in the complete darkness.
How do Octopuses see the world?
Octopuses are myopic or short-sighted and have blurry vision. They see the world without any sharp details but can easily recognize nearby objects. Also, depending on the situation and refraction, their eye status change to normal-sightedness.
Octopuses can see everything in their surrounding with blurriness and without any blindspot. They have more photoreceptors (around 20,000-50,000 per millimeter square) in their eyes compared to humans. It clearly demonstrates that their vision is far much better than humans.
Over centuries, octopuses’ eyes have evolved into seeing much better underwater. Even in their hazy vision, they are well aware of their predators and prey, and their blurriness is totally dependent on the color.
They can also differentiate various color shades by sensing the wavelength. Octopuses can easily identify yellow or blue colors with a unique range of wavelengths but are very bad at identifying white objects that reflect all wavelengths of light.
Octopuses can easily differentiate colorful rocks, algae, corals, etc., depending on the wavelength of color that they are emitting.
Also, according to many researchers, it is estimated that octopuses can also see ultraviolet light. It assists them in capturing their prey in the complete darkness that emits UV lights.
Can Octopus see in the Dark?
Octopus can see in the dark. They don’t need eyes to see light underwater. With the help of their tentacles, they can efficiently sense their environment and navigate even in the complete darkness. It is unveiled in the research that octopuses’ arms quickly react to light.
As explained above, the skin on their arms is covered with a pigment-filled organ known as chromatophores. It quickly responds to any light that helps octopuses to navigate or search for their food.
Also, octopuses don’t have tapetum lucidum like sharks and dolphins in their eyes. Therefore, they primarily rely on their tentacles to sense their surroundings.
In addition, octopuses can detect polarized light and can also create signals using polarized light on their skin. In this way, they communicate with each other.
Can Octopus see color?
Yes, octopuses can see color with the help of their pupils. They have only one type of photoreceptor that allows them to see only black and white. But their pupils force light to enter the retina from the direction and have the ability to recognize the color based on their wavelength.
Every color has its own wavelength, and octopuses can distinguish the wavelength. In this way, they can see even more colors than humans, including ultraviolet and polarized light.
Do Octopuses have good eyesight?
Octopuses have very good eyesight to navigate underwater clearly. They are near-sighted but can notice everything that is happening in their environment. They are also well-aware of their surroundings and have no blindspot.
The eyes of the octopus have roughly up to 50,000 per millimeter square photoreceptors, which is far more than any vertebrates. Not only this, they have a monocular field of vision.
Octopus vision vs Human vision
|Octopus Vision||Human Vision|
|Octopuses have monocular vision.||Humans have binocular vision.|
|They are monochromatic.||We are trichromatic.|
|They can also recognize ultraviolet and polarized light.||Humans cannot distinguish ultraviolet and polarized light.|
Here, we conclude our article on “What and How do octopus see” and explain a brief comparison with human vision. We hope you like it. We will be back with another post. Till then, stay tuned with us and read the articles mentioned below.
Image Source- Photo world tours, Camera stuff review
The Eye of the Common Octopus by Frontiers in Physiology
Monty is a founder of How It See. Being a life science student in a reputed university, he always wonders about an eclectic correlation between science and nature. After engaging in various college projects, Monty determined to share all his knowledge with you as a writer. In the meantime, he loves to research and study about the various types of colorful animals.