Ron Kruger shares the scientific information on how bass see.

In the first place, it probably is a mistake to judge the vision of the bass on our own because bass see everything a bit differently than us, and not just because they live in different environment. It’s because their eyes function much differently than ours.

For one, their eyes are placed on the sides of their heads, affording them “monocular vision,” which means they can see well on both sides of their heads simultaneously. Each eye has the ability to see over a 180-degree range, so their only “blind spot” is a narrow area directly behind them where their body obstructs their vision. We have “binocular vision,” which restricts our field of view to the front but allows us great depth-of-field perception.

Fish are nearsighted, so unless a lure makes noise, it needs to be cast closely to a bass to be detected. Fish also have limited binocular vision, similar to ours, and in a narrow band directly in front of them. Their binocular vision, however, is really just an overlapping of their monocular vision. So although they can see things at a little greater distance, the objects are blurred and depth perception is impaired, sort of like the way we see if we cross our eyes slightly. This is why you often see a bass make a little swoop to the side at the last second before they strike a lure they’ve been following from behind. This little sidestep at the last second allows them to see the bait the most clearly the instant before they take it. Short strikes or complete misses could mean they saw something distasteful upon closer inspection. Under their clearest vision and during a last-second swoop, a bass sometimes changes its mind like a batter checking his swing on a pitch he decides is not good to hit.

Scientists believe that bass receive about five times more light through their eyes than humans. This, of course, gives them better vision in deep, dark areas, but it doesn’t mean they can see five times better than a human. Simply put, they are five times more sensitive to light. They have a fixed lens, and their cornea is of uniform thickness. They don’t have eyelids or pupils to dilate and compensate, so they make up for this by seeking shade or moving deeper. The bass need this extra sensitivity because water absorbs light quickly. The deeper or more turbid the water, the less light there is to reflect off objects. Plus, when ripples break the surface, some of the light is refracted so the diffusion of light is rapid. Often, just a few feet or the shade of a fallen tree is enough. MWO

Want to learn more about how bass see underwater?  Check out the June issue of MidWest Outdoors magazine, available at a newsstand near you. You may also subscribe to MidWest Outdoors online or by phoning 800-606-3474.