To truly appreciate this exceptional predator, you need to know how they see, hear, feel, smell and taste. Doing so will result in a more frequent, up-close and personal look at North America's most prominent fish on the end of your line.
The eye of the beholder
Sight is probably the most important sense of the bass
genus. I say "probably" because most of the research on bass to date
has focused on population management, life history, predator/prey interactions,
reproductive biology, etc., rather than specific physiological characteristics.
However, we do know enough about similar species — and bass in general — to
draw some conclusions.
To understand the commitment to sight in the bass species,
one needs look no further than the fish's brain. The ocular lobe of the bass is
huge, relatively speaking. This means that the fish invests much of its
neurological resources in its ability to see.
Anecdotal evidence seems to confirm what scientists see in a
lab. In perpetually turbid or dingy waters, bass struggle to grow to trophy
size, even if the waters are fairly productive. Why? They can't see well enough
to find adequate prey. That's nothing new to the average bass angler. But, what
do bass really see? To understand that, we must look at the eye structure itself.
They have bulbous, protruding eyes positioned on both sides
of the head that enable them to see a much wider field of view than you or I
can see. Basically, their only blind spots are directly below and behind them.
However, much of that sight is monocular, rather than
binocular. What's the significance? In order to focus on an object and truly
get a good view, both eyes have to see it simultaneously. That means the bass
has to be facing the object to discern the true shape and distance, and even
then, it has to be pretty close. They may be able to detect motion on one side
or the other, but they don't truly understand what they are seeing until they
position themselves so that both eyes are peering in the same direction.
Now for the most popular question we biologists get about
bass vision, do bass see color? Without a doubt, yes! Not unlike humans, bass
have cellular structures in the retina called cones and rods. Rods allow an
animal to see black, gray and white in low-light conditions, while cones allow
an animal to see colour. The exact kind and quantity of cones in bass is
uncertain, but the plentiful existence of cones, along with related research,
indicates that color selection can be important, depending on the conditions.
Colour is a product of light. Light is both absorbed and
refracted by water, and the shorter the wavelength, the deeper the colour can
penetrate. In clear water, the blue end of the spectrum is visible at the
deepest depths, while the red end is absorbed more quickly.
However, the clarity of the water also plays a role. If
there is a strong algal bloom, or the water is muddy from a recent rain, light
behaves differently. In these conditions, colours that contrast with the
surrounding water will be noticed more quickly. At night, bass rely on their
retinal rods, just as we do, to see shadows and movement. During new moons,
there isn't a lot of ambient light in the water, and it dissipates quickly with
depth. In these conditions, darker lures have more contrast and can be seen
better. On bright, moonlit nights where more light penetrates, more lure colours
will be visible to a bass.
Bass can see colour. Paying attention to colour can make the
difference between a curious follow and a definitive attempt to eat your lure.
Perhaps the second most important sense for bass is both hearing and
feeling. Wait, isn’t that two senses? Well, for a fish, they’re very closely
related. In order to understand how a fish hears and feels underwater, we need
a quick refresher on physics.You see, sound is nothing more than energy travelling through a medium. The medium could be a solid, liquid or gas, but there must be the presence of mass in order for sound to travel. When you beat a drum, some of the energy from striking the drum surface is transferred to the air around it via vibrations of the surrounding air particles. These vibrations are passed along to the next particles of air, then the next and next and so on until it reaches your ear, where the vibrating particles cause your ear’s tympanic membrane to vibrate, which your brain interprets as sound.
Sound travels about five times faster in water than it does in air, and about five times faster again in a solid like steel. The denser the medium, the more particles there are to vibrate and the faster energy can be passed from one particle to another.
Now, back to what this means for bass. Water is already much more efficient at transferring sounds than air, so bass — and fish in general — are able to detect sounds more quickly and efficiently than humans. But how do they do it? They obviously don’t have ears … or do they?
Although they don’t have external oratory canals, bass do have internal ears that allow them to hear sound in the water, just as we do in air. Their inner ear also serves to help orient them in the water, just as our inner ear helps us to maintain our balance by telling our brain which way we are leaning.
However, fish take hearing underwater a step further. Bass, like most freshwater fish, have an additional sensory organ for their underwater environment — the lateral line. Now, I’m not talking about the long, wide black colour blotches that run down the side of a largemouth or spotted bass.
The lateral line is a series of pores or canals in a row of scales that stretch from just behind the gill plate to nearly the tail in a bass. They are perceptible, but you have to look closely. These canals contain a series of cells that have hair-like extensions surrounded by a gelatinous substance, together called neuromasts. Vibrations from surrounding water on one or more of these groups of cells send a signal to the bass’ brain that — along with the same effects on the inner ear — it interprets as sound.
So how do bass feel? They obviously don’t have digits with extra sensitive nerves under their skin as we do. However, like with sound, the system of neuromasts in the lateral line can also sense the slightest changes in water pressure. When another fish swims by, the resulting difference in water pressure from the moving fish travels to the bass in waves. When the hair-like structures in the nueromasts are bent in a certain direction from the resulting wave pressure, they tell the bass not only what happened, but where in relation to the bass’ position and in what direction the movement occurred.
Pretty amazing, isn’t it? The lateral line not only allows fish to hear underwater, but it enables them to feel what is going on in the neighbourhood.
Anybody that’s ever ripped a lipless crankbait through the grass knows that sound travels very well in water, as evidenced by the rapid ticking noise emanating through the bottom of the boat as you sweep the lure. On days when bass are reacting to the bait without much scrutiny, or when the water conditions and light are such that they can’t see it very well, a loud lure certainly gets their attention.
However, even if you’re fishing a good ol’ Texas-rigged worm without any rattles, rest assured that if you get it close to a bass, it’ll know where it is, even if it can’t see it.
Originally
published January 2011
