Dolphins have fascinated humans for centuries with their intelligence and friendly nature. But one question that often comes up is – can dolphins see? If you’re short on time, here’s a quick answer: dolphins are not blind. They have excellent vision both in and out of the water.
In this comprehensive article, we’ll cover everything you need to know about dolphin vision and eyesight. We’ll discuss dolphin eye anatomy, how well dolphins can see underwater and above water, whether they see in color, how their vision compares to human sight, and more.
Dolphin Eye Anatomy
Cornea, Iris, Pupil
Dolphins have excellent vision both in and out of the water. Their eyes are specially adapted to see clearly even in the murky ocean depths. The cornea is the transparent outer layer of the dolphin’s eye that refracts light.
Underneath lies the iris, which is a muscular structure that controls the size of the pupil. The pupil is the opening at the center of the iris that allows light to enter the inner eye. It dilates and constricts to regulate the amount of light entering the eye.
Dolphins have relatively small pupils compared to other mammals, which may help filter out ultraviolet light in the water.
Lens
Behind the pupil is the lens, which focuses light onto the retina. The dolphin lens is spherical and inflexible, unlike the adjustable lenses of humans and other land mammals. However, it has a powerful ability to accommodate, meaning it can change shape slightly to focus on objects at different distances.
Researchers believe dolphins accommodate by moving their lens back and forth, rather than altering its curvature like other mammals. This allows dolphins to see clearly both above and below the water’s surface.
Retina
The retina lines the back inner wall of the eye and contains photoreceptor cells called rods and cones. These cells convert light into electrical signals that are sent to the brain. Dolphins have a high concentration of rods compared to cones.
Rods function well in low light conditions, which enables dolphins to see underwater where sunlight quickly diminishes. The high rod density also means dolphins have excellent night vision. However, they have poor color vision with just blue and green color reception.
The dolphin retina has a reflective layer called the tapetum lucidum, which bounces light back through the rods to enhance vision in dark or murky waters. It creates the distinctive eye shine seen in dolphin eyes at night.
How Well Can Dolphins See Out of Water?
Dolphins have excellent eyesight both in and out of the water, though their vision does work a bit differently on land versus underwater. Here’s a closer look at how well dolphins can see when they’re above the surface:
Adapted for Aerial Vision
While dolphins are aquatic mammals, their eyes are adapted for seeing clearly in air as well as water. When out of the water, a dolphin’s lens circularizes and its cornea changes shape to allow for aerial vision. This quick adaptation gives dolphins excellent long-range vision above water.
Wide Field of Vision
Dolphins have a nearly 360-degree field of vision thanks to the placement of their eyes on the sides of their heads. This gives them the ability to see nearly all around themselves while above water. Their binocular vision directly in front of them is about the same as humans at 55 degrees.
Excellent Dynamic Range
The dynamic range of a dolphin’s vision describes the range between the dimmest and brightest light levels they can perceive. Dolphins have a dynamic range of around 48 units compared to a human range of 1,000 units.
This means dolphins can see quite well even in low light conditions above the surface.
Able to See Color
Dolphins have color vision, despite the misconception that their world consists only of shades of gray. They have a single cone photopigment for brightness detection and one for color detection. This allows them to see colors, especially shades of green and blue, when out of the water.
Better Vision Underwater
While dolphins see very well in air, their vision is even more adapted for underwater viewing. When submerged, the dolphin’s lens rounds and cornea flattens to allow for superior underwater eyesight. So while they have excellent aerial eyesight, a dolphin’s vision is optimized for the aquatic environment.
Dolphin Vision Underwater
Light Adaptations
Dolphins have excellent underwater vision thanks to evolutionary adaptations to seeing in the ocean. Their eyes are specially adapted to filter out extremely bright sunlight at the water’s surface while also gathering enough light in the dim depths where visibility falters.
The structure and placement of a dolphin’s eyes gives them great all-around vision above and below the water. Dolphins have a reflecting layer at the back of their eyes called the tapetum lucidum that bounces light back through the retina, essentially giving their eyes a second chance to capture images (Yopak, 2012).
This adaptation allows dolphins to see exceptionally well in low light underwater.
Additionally, dolphins have high concentrations of light-sensitive rod receptors compared to color-detecting cone receptors. Their retinas contain only one cone for every 30 rods. This ratio results in excellent night vision and the ability to detect quick movements, which is vital when hunting fast-moving prey like fish in the ocean (PBS).
Dolphins also have a circular lens that can change shape to easily adjust between seeing above and below the water’s surface (Whale & Dolphin Conservation). The muscles controlling their lens allow it to rapidly constrict and relax as needed when the dolphin dives into deeper or shallower waters.
This flexibility prevents distortion and allows crisp vision at varying ocean depths.
Size and Placement of Eyes
Dolphins have excellent peripheral vision due to the placement and proportions of their eyes. Their eyes are located on the sides of their relatively large heads, giving them a panoramic view of their surroundings (PBS).
This wide scope of vision coupled with good low light capabilities allows dolphins to detect potential predators and prey approaching from nearly any direction. Their broad field of view spans approximately 180 degrees horizontally and 180 degrees vertically, meaning they can see clearly behind themselves without turning their heads.
Additionally, a dolphin’s eyes are specially proportioned to function well underwater. The cornea and lens of a dolphin’s eye are much more curved than a human eye, resulting in strong refracting power that focuses well on nearby objects underwater (WDC).
The sizeable eyes and visual cortex in the dolphin brain also contribute to excellent sight. Dolphins dedicate a large portion of their brain power to processing visual stimuli, particularly fast-moving objects that require quick reaction times during hunting and navigation.
Do Dolphins See Color?
When it comes to dolphin vision and their ability to see color, the simple answer is that researchers are still trying to fully understand dolphin eyesight. However, studies so far show that dolphins do have some limited color vision, but not to the extent that humans do.
Dolphins have a single cone photopigment in their eyes responsible for daylight vision, while humans have three cone cell types that allow for perceiving the color spectrum. So while dolphins cannot see the array of colors that humans do, they are not completely colorblind.
Research indicates that dolphins have enough photopigments to differentiate between some colors like blue and yellow. However, their world consists mostly of dark, light, and gray contrast. This actually suits their underwater lifestyle, as too many colors could be confusing and counterproductive when navigating the ocean.
An interesting study published in the journal Nature in 2019 provided insight into dolphin vision. Researchers sequenced the dolphin genome and found that dolphins lack the genes needed to produce red and green photopigments.
But they do have the genetic basis for a single type of cone photoreceptor sensitive to blue light.
So how does the dolphin visual system work? Dolphins have excellent eyesight both in and out of the water. Their eyes are specially adapted to function well in two different media – air and water. They have strong lenses, increased density of rods and cones, and a reflective layer that bounces light back through retinal cells.
While dolphins may have limited color vision, their senses are incredibly well-adapted to their marine environment. They utilize echolocation to build a detailed visual map, have excellent night vision, and can detect fast-moving objects.
So while dolphins live in a less colorful world than humans, their unique visual abilities allow them to thrive in the ocean.
Key Points
- Dolphins have limited color vision – they can likely differentiate between some colors like blue and yellow.
- Dolphins lack red and green photopigments, but have genetic evidence for blue light sensitivity.
- Their vision is well-adapted to function both underwater and in air.
- Dolphins rely more on contrast, light sensitivity, night vision and echolocation rather than a colorful visual spectrum.
Dolphin Vision vs. Human Vision
Field of View
Dolphins have a much wider field of view compared to humans. Their eyes are located on the sides of their heads, giving them a field of view of around 300 degrees horizontally. This allows dolphins to see nearly everything around them without having to move their heads (1).
Humans, on the other hand, have a horizontal field of view of around 180 degrees since our eyes face forward (2).
This wide field of view helps dolphins detect predators and prey. They can see danger approaching from nearly any direction. Humans have great depth perception thanks to our binocular vision, but we have large blind spots to the sides and back.
Dolphins evolved eyes on the sides of their heads to eliminate those blind spots and continuously monitor their surroundings.
Seeing in Low Light
Dolphins can see exceptionally well in dim, murky waters thanks to several visual adaptations. Their pupils dilate widely to allow more light in, and they have a reflective layer behind their retina called the tapetum lucidum that acts like a mirror, bouncing light back through the retina to essentially give it two chances to be detected (3).
This adaptation allows dolphins to see up to 10 times better than humans in low light conditions.
Humans do not have a tapetum lucidum, so we struggle to see clearly underwater, especially at depth where light dims significantly. Many divers need to carry flashlights and underwater cameras often have built-in lights to compensate.
Dolphins’ excellent low light vision gives them a huge advantage for finding food and navigating dark waters.
Focusing Ability
Unlike humans, dolphins can focus both underwater and in air. Our eyes are adapted for air – the refractive index of air and our corneas are very similar. But the refractive index of water is significantly different, so our vision gets blurry underwater unless we wear goggles or masks designed to correct for the difference (4).
Dolphins’ eyes, however, are adapted for both mediums. Their corneas have very high refractive powers that change depending on whether they are above or below water (5). This helps dolphins seamlessly transition between crystal clear air vision and underwater vision.
Their dynamic focusing abilities allow dolphins to effectively hunt, navigate, and socialize in both environments.
Conclusion
As we’ve explored, dolphins have extremely sophisticated vision adapted for life in the ocean and out. While their sense of sight differs from humans in some ways, overall dolphins see quite well – they definitely aren’t blind!
Key takeaways about dolphin vision include:…
We hope this deep dive shed light on the excellent eyesight these marine mammals possess. Understanding how species see and sense the world around them is key to learning more about their behavior and intelligence.