The lateral line has always been considered as one of the most important elements in the sensory arsenal of the bass, but is that really the case? The real answer may shock you.

Laboratory studies have proven to a scientific certainty that a completely blind fish can feed by the exclusive use of the lateral line, but that does not prove that it is used either partially, or even at all, in the feeding processes of normal bass with no sensory impairments. Furthermore, these studies note that feeding efficiency of these fish, based on percentages of successful capture of prey, is below normal at best. What we must understand up front that, while the predatory and feeding responses of bass and other animals may be based on instinct, they are to a large degree learned behaviors as well. The feeding reflex would be better described as a learning process driven by the instinct to chase and capture food.

Take ourselves as an example and consider a learned skill that is totally dependent on sight, like walking from place to place: In this case, we are, for the most part, completely reliant on our eyesight to avoid obstacles, but many blind people get along amazingly well by feeling their way with a cane, although their performance of this skill would still be considered “impaired”. Sighted people make absolutely no use of this “sense”, even though, in many cases, they would be capable of learning the skill. Imagine not having to disturb others by turning on the lights in the middle of the night to go and get a glass of water! Many of life=s skills are learned based on necessity, and I am not convinced that bass need to be able to rely heavily on their lateral lines for feeding, any more than a sighted people need to learn to walk with a cane. Bass have two eyes and the process of loosing their sight is probably progressive and gradual, allowing them time to learn skills that would finally and by necessity base their reliance on other senses.

When it comes to capturing prey, even the scientists say that the eyes and mouth of a bass are the key players and they are oriented forward and up. Because the body of the bass is tapered toward the tail, when pursuing prey, the lateral line is oriented to the side and even toward the rear.

So is this organ really keyed in on prey in the bass? My answer would be, probably not, unless he is blind or deaf or both.

That brings us to the question of what the mysterious lateral line really does and whether or not it should be involved in your choice of level and pattern of vibration in lures.

I believe the lateral line in most fish, and bass in particular, gets the emphasis it does because it is a conspicuous organ and unique to fish. Anglers have a keen interest in appealing to their quarry on every level possible and cannot ignore the lateral line. This despite the fact that we know for a fact that we know bass have highly developed eyes oriented to the front for feeding. As a result they tend to be extremely stimulated by visual cues like patterns of movement, shape, speed and color. The lateral line on the other hand is on the side of the fish, because maximum length is critical to its function. The only benefit to being long would be to resolve and analyze impulses that vary along its length. This advantage of this length would be greatly enhanced as the source of vibration got progressively closer to the fish and the lateral line. If the source of stimulation were extremely close, the lateral line would span almost 180 degrees of the circle of energy being radiated. If the vibration occurred a mere 10 feet away, the foot long lateral line of an eight pound bass would have only a 6 degree sliver of that arc to work with. This leads me to believe that the major use of the lateral line is to sense things very close to the fish, the closer the better. Close enough and you get your ideal 180 degrees no matter how small the fish. This is the only explanation that makes any sense, because virtually all fish, from tiny to huge, have a lateral line organ. I believe it would be great for sensing current direction, the most efficient flow pattern of water over the body during high speed swimming, and I believe it is the lateral line that, by feeling the water flow off of the bodies of adjacent fish, allows large schools of fish to swim in surreal unison. When they are packed in huge schools of tiny fry shortly after hatching, even bass exhibit this amazing “skill” that so mesmerizes and thwarts predators.

So are patterns of vibration important to consider in your choice of lures? I would have to say yes, but most in terms of how they affect the visual signature of motion rather than the subsonic profiles that they emit. And remember, the most productive lure of all time is the plastic worm, which is often fished in a way that produces no vibration at all.

Sound chambers and vibration patterns became a huge selling point with lures in long before the loud, clattering, and vibrating lures we are so familiar with today. In many cases they were sold on the premise of appealing to lateral line perception.

It would surprise many of you to know that sound travels so efficiently in water, that the energy from a Fourth-of-July firecracker, which is harmless in the air, can seriously injure or even kill a scuba diver. While we see no external ears on a bass, the fact that sounds travels right through them makes internal ears work just fine. The problem is that sound travels so efficiently under water that it is almost impossible to position precisely. It is the same principle that makes it seem like the sounds of a workman fixing a radiator in a large building always seems to come from the radiator closest to you, no matter that the work may be taking place many rooms or even floors away. As a result, I choose noise-making lures in situations where bass have good distance visibility, like the outer edges of weed bed or even open water trolling. In these situations, bass that are looking for the source of a sound have a better chance of finding it visually. It is because, sound travels so poorly in air we have very good positioning clues: if our head is turned to the side it is louder in one ear than the other, it falls off drastically with distance, and so on. So, while science can prove that fish are endowed with remarkable capabilities by virtue of an organ such as the lateral line and even the inner ear, it does not prove that all capabilities are fully utilized at all times and for all tasks. I thereby choose to place most emphasis on those feeding tools that are oriented toward the intended prey. That is why I will always reach for a lure with natural looks and motion. Along with their big mouths bass have excellent vision, with full-spectrum color perception.

Bass also have excellent hearing, a great sense of taste and smell, and a good low frequency energy detector in the lateral line. Science continues to work hard at developing lures that, not only look good and move with the proper action, but also with sounds, even tastes, smells, and vibrations that are appealing to fish…but that’s another story.

Doug Hannon- The Bass Professor
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