The octopus has two protruding eyes on either side of its head, allowing it to have excellent vision due to their bilateral body symmetry.
The octopus has unique and fascinating vision, with amazing pupils and eye muscles allowing them to detect color, polarized and night vision, making them able to see better than humans.
Octopuses are the most intelligent invertebrates that have eight arms, three hearts and nine brains. Their level of ingenuity encompasses using tools, solving puzzles and problems, changing color and skin texture, get in and out of tight spaces, and even recognizing human faces—a marvel of natural evolution of 140 million years.
Octopus Eyes Count
Octopuses have two large eyes that can compress their circular pupil in bright light to form a horizontal slit in dim light, offering superior vision.
Octopus Eye Size
The octopus has big eyes compared to its body, ranging in diameter from half an inch to one inch.
Even though humans and octopuses have similarly structured eyes, octopuses are more efficient in quickly focusing on moving objects, although they have fewer vision problems.
Octopuses have some eye structures in common with humans, like the lens, iris, retina, and optic nerve, but lack corneas due to a movable lens that allows for the quick change of focus.
Comparing Human Eyes with those of Octopuses
The octopuses move their lens in or out to focus, unlike human eyes that use muscles to adjust the lens’ shape. Moreover, their pupils allow rotation of up to 80 degrees, offering them monocular vision with no natural blind spot.
Octopus Eye Development
An inward fold in the outer layer forms the octopus eye while in the egg, availing a retina free of nerve connections, creating proper eyesight.
Colors Recognized by Octopus Eyes
The octopus eye detects color even though it only has one type of light receptor.
However, octopuses can differentiate between colors through the interaction of their unique pupils, which can act as prisms, and their ability to process different wavelengths of light using chromatic aberration, which enhances contrast and makes disguising from or warning away predators easier.
Octopus Without Blind Spots
The optic nerve arrangements of octopuses facilitate no blind spots, unlike the human eye, which senses the blind spot through one eye, while the other eye compensates for it.
Octopus Myopia
Octopuses can see nearby objects but are typically myopic, yet they have a muscle to move their eyes’ lens closer to the retina, enabling near-normal eyesight.
Octopus and Polarized Light
Octopuses sense polarized light and use the ability to differentiate between objects, display communication, and navigation abilities, much like humans using color vision.
Octopus Night Vision
Octopuses are nocturnal creatures, having night vision that works excellently alongside daytime vision, allowing them to wander on land in search of food easily.
Octopus Vision as an Independent Process
Octopuses primarily use one eye at a time via monocular vision, having the ability to move each pupil independently using nerves and muscles, offering them the ability to rotate their pupils up to 80 degrees in both directions.
Octopuses and Blue Blood
Octopuses have blue blood facilitating the transport of oxygen more efficiently and are rich in copper-based hemocyanin protein.
Octopuses Detect Light Without Eyes
Octopuses have cells beneath their skin with light-sensitive proteins to sense light, indicating they could detect light with their skin theoretically.
Octopuses Detect Smells Without Noses
Chemical sensors at the ends of octopuses ‘ arms allow them to sense smells, taste, and feel, even without a nose, helping them detect and avert predators from a distance.
References
- Hanke et al. “The Eye of the Common Octopus (Octopus vulgaris).” Front. Physiol. January 2020.
- Stubbs et al. “Pupil Shape and Chromatic Aberration Can Provide Spectral Discrimination for Color Blind Animals” Museum of Vertebrate Zoology, Dept. of Integrative Biology, UC Berkeley April, 2015.
- Buresch et al. “Contact chemoreception in multi-modal sensing of prey by Octopus.” Journal of Comparative Physiology, April, 2022.
- Courage, KH. “Is Smell the Key To an Octopus’s Heart?” Scientific American, October, 2014.
- Byrne, RA. “Lateral asymmetry of eye use in Octopus vulgaris.” ANIMAL BEHAVIOUR, 2002.
- Ogura et al. “Comparative Analysis of Gene Expression for Convergent Evolution of Camera Eye Between Octopus and Human.” Genome Research, April, 2022.
- Zhang et al. “Cone photoreceptor classification in the living human eye from photostimulation-induced phase dynamics.” PNAS, April 2019.
- Rhodes, MJ. “Prospective Pilot Study Looking at the Size and Variation of the Blind Spot Scotoma in Adults Measured on the Octopus 900 Field Analyser.” Ophthalmology Research: An International Journal, 2013.
- Temple et al. “Thresholds of polarization vision in octopuses.” Journal of Experimental Biology, April, 2021.
- Bekerman et al. “Variations in eyeball diameters of the healthy adults.” Journal of Ophthalmology, November, 2014.
- Cuff et al. “Crystal structure of a functional unit from Octopus hemocyanin.” Journal of Molecular Biology, May 1998.
- Katz et al. “Feel the light: sight-independent negative phototactic response in octopus arms.” Journal
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