Do Sharks See In Color?

Sharks are fearsome predators, not just because of their size — and sharp teeth — but because of their intelligence. They are able to seek out their prey not just on mere instinct, but also because they have a fairly large brain, with well-developed sensory systems. And while they usually don't actively seek out human beings for their prey, sometimes unfortunate circumstances have led to unwanted interactions between humans and sharks (via Florida Today).

Researchers from the University of Western Australia and the University of Queensland in Australia were trying to come up with ways to reduce the chances of unfortunate tangling between humans and sharks in 2011, which led them to explore just how advanced sharks' sensory systems are, particularly in regards to their color vision. If sharks are drawn to certain colors, the researchers speculated, then limiting the use of those colors in tools like fishing lines or swimming attire may help reduce the risk of catching a shark's attention. And while that was certainly an interesting theory, the results of their study indicated that sharks are not able to see in color. "Our study shows that contrast against the background, rather than color per se, may be more important for object detection by sharks," Dr. Nathan Scott Hart, the lead researcher in the study published in the journal Naturwissenschaften, reported.

Sharks are effectively colorblind

While sharks do have well-developed eyes, the study revealed that they have just one single type of cone photoreceptor in their retina, which means they are unable to distinguish colors, according to ABC Science. The findings may have come as a surprise to some, because rays, which are a close relative of sharks, are in fact able to see in color. Some research has suggested that the reason rays see in color while sharks do not is due to the fact that color sight helps the rays, who spend most of their time in shallower water, more easily spot oncoming predators, who often use light as camouflage, according to the Shark Research Institute. Sharks, as apex predators who largely spend their time in deeper waters, are less likely to need to distinguish between colors for those reasons.

While they may not see in color the way humans do, sharks still have impressive vision for their own purposes. In order to reduce the risk of inadvertently drawing the attention of sharks, people should focus on avoiding color contrast, rather than zeroing in on any one specific color. "This may help us to design long-line fishing lures that are less attractive to sharks as well as to design swimming attire and surf craft that have a lower visual contrast to sharks and, therefore, are less 'attractive' to them," Dr. Hart concluded.