In honor of Shark Week, let’s take a deeper dive to explore shark vision.
Sharks primarily use their sense of sight when closing in on prey and can see clearly about 50 feet away; however, they don’t rely on vision alone – sharks can sense electrical signals through pores near their nose that help detect their location and proximity to other animals.
A shark’s eye structure is actually very similar to humans. In fact, the tissue is so similar to the human eye that shark corneas can be used in a corneal transplant on humans.
Sharks don’t need to blink nearly as much as we do, if at all. Sharks tend to close their eyes to protect themselves primarily while feeding; however, some species like great white sharks and whale sharks do not have eyelids. Instead they roll their eyes into their head while feeding. Some species of sharks have a nictitating membrane, also known as a third eyelid, which provides a protective barrier over their eyes without impairing their vision.
What is most remarkable about sharks’ vision is the ability to see in the dark. They can see about 10x better than humans in the water. How do they do it? Sharks have a structure in their eye called the tapetum lucidum, which reflects light that has entered the eye. This structure is also present in deer and cats, and is what gives them the appearance of glowing eyes at night. Some sharks can see better in the dark than others. A recent study on bioluminescent sharks shows that their eyes have higher density of rods that help them survive in the ocean’s twilight zone (only about 12 percent of sharks are bioluminescent).
With all of their unique vision capabilities, it’s hard to believe there could even be a myth that sharks cannot see very well!