Shark eyes have always appeared to be a bit of a mystery. We commonly hear about the mistaken identification argument relating to shark-human encounters, which causes people to assume that sharks have poor vision. We also often hear about sharks’ great sense of smell, and it’s generally considered that certain other feelings are compromised as a consequence. Is this true? Do sharks have a weak vision?
A research group in Australia has been investigating shark vision for years. In fact, they may be the world’s authorities invertebrate vision and have researched the eyes of literally hundreds of different species of elasmobranch (sharks, rays, skates, and sawfish) (sharks, rays, skates, and sawfish). Here, we’ll attempt to synthesize their results and explain what that implies in practical terms.
Sharks lack color vision.
That’s correct. Sharks lack the essential cells that process color vision and can only see in Black & White. This appears to be the case for all sharks since none of the examined animals contained the essential photoreceptor cells to see in color. So what’s all the buzz about Yum Yum Yellow? We’ll go back to it. On a side point, rays can see in color.
Visual intensity of sharks.
Sharks are supposed to be able to perceive incredibly full pictures. The fact that shark eyes is monochromatic does not indicate they lack visual acuity. In the human eye, we have muscles that govern the curvature of our lens and focus light signals on the retina. By contrast, the lens of a shark’s eye does not alter its shape. Instead, they feature muscles that move the lens forward or backward to focus light. In both circumstances, the result is the same, and the retina gets a focused picture. Sharks have remarkable visual acuity, and they totally depend on that vision for many of their actions. Obviously, water conditions will have a massive influence on their capacity to see and from what distance. In optimum circumstances (the type we experience when diving in the Bahamas), sharks can see well from 10-15 meters or more. This means although their vision is strong, it’s not the initial sense that hooks them into their prey and becomes increasingly crucial as they move closer.
Sensitivity of shark eyes.
The capacity to see in low light situations differs substantially amongst the shark species tested. Essentially, there are 2 kinds of photoreceptor cells situated in the retina. The cones are active in bright light settings, while the rods are active in low light scenarios. Each species will have a different percentage of these cells. Not unexpectedly, deep water sharks have giant eyes with a substantially more significant portion of low light photoreceptor cells (rods) compared to cones. Shallow water sharks contain cells in the opposite proportion. In addition, sharks possess a tissue called the Tapetum lucidum. This reflects the eye’s region that sits beneath the retina and creates the gleaming eye you may have seen in a cat or a deer in headlights. This will reflect the light one more time back through the retina, making it accessible to the retina a second time and boosting low light vision.
Sharks have the monochrome vision. Sharks have high visual acuity. Sharks have a vision tailored to the environment they live in. Given their intense concentration and black and white perception of the world, do we need to care about the color of our diving gear? In short, Yes! Sharks do seem to be interested in high-contrast locations. It’s the reason we don’t like really vivid accent colors on diving gear since it may catch their attention. It’s also the reason we need divers to wear gloves on our shark dives. A pale fleshy hand poking out of a black wetsuit sleeve may be a recipe for danger.
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