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The Senses of the Largemouth Bass and How They Relate to the Largemouth Bassís Feeding Habits

By Ryan Meyer


Successful survival in any environment depends upon an organism's ability to acquire information from its environment through its senses. Largemouth bass have many of the same senses that we have, they can see, smell, touch, feel, and taste, and they have developed some senses that we don't have, such as electroreception. Bass can sense light, chemicals, vibrations and electricity. The following will discuss the senses of the largemouth bass and how these senses relate to the largemouth bassís feeding habits.

Vision: (Photoreception)


Bass have a very keen sense of vision, which helps them to find food, shelter, mates, and avoid predators. Bass, like us, turn light into neural impulses through transduction in the photoreceptors. Bass vision is on par with our own vision; many can see in color, and some can see in extremely dim light. Bass eyes are different from our own. Their lenses are perfectly spherical, which enables them to see underwater because it has a higher refractive index to help them focus (Reference 3, 1997). They focus by moving the lens in and out instead of stretching it like we do. They cannot dilate or contract their pupils because the lens bulges through the iris (Reference 3, 1997). Largemouth bass have a special eye structure known as the Tapetum lucidum, which amplifies the incoming light (Reference 3, 1997). It is a layer of guanine crystals which glow at night. Photons which pass the retina get bounced back to be detected again. If the photons are still not absorbed, they are reflected back out of the eye (Reference 3, 1997).

Figure 1: Picture of a largemouth bass showing the eye position.

When fishing for bass in low visibility conditions ( overcast sky) or in murky water, try using light colored (white or silver) or neon colored (chartreuse) lures. These colors tend to give a good light reflectance which allows the bass to see the lure quicker and give it a better chance to react to your presentation. In high visibility conditions such as clear water and clear skies, use dark colored lures. In these conditions, dark colors appear to be more natural and appetizing to the bass.

Smell and Taste: (Chemoreception)


Chemoreception is very well developed in bass and other fish, which rely upon this to detect their prey. Largemouth bass have two nostrils on each side of their head, and there is no connection between the nostrils and the throat. "The olfactory rosette is the organ that detects the chemicals. The size of the rosette is proportional to the bass's ability to smell" (Reference 3, 1997). Bass also have the ability to taste. They have taste buds on their lips, tongue, and all over their mouths. This is why when fishing for bass with artificial lures, you normally only have about a second to set the hook before they spit out the lure. Scented lures like Berkley Power Worms, make it so bass hold on longer because of their taste and scent.

Hearing and Touch: (Mechanoreception)


Have you ever seen a bass's ear. Probably not, but they do have them, located within their bodies as well as a lateral line system that actually lets them feel their surroundings. Bass do not have external ears, but sound vibrations readily transmit from the water through the bass's body to its internal ears (Reference 3, 1997). The ears are divided into two sections, an upper section (pars superior) and a lower section (utriculus) (Reference 3, 1997). The pars superior is divided into three semicircular canals and give the bass its sense of balance. It is fluid-filled with sensory hairs. The sensory hairs detect the rotational acceleration of the fluid. The canals are arranged so that one gives yaw, another pitch, and the last- roll. The utriculus gives the bass its ability to hear. It has two large otoliths which vibrate with the sound and stimulate surrounding hair cells (Reference 3, 1997).

To utilize the bassís sense of hearing, when using a Stanley Jig, attack a rattle to the body of the jig under the skirt to give the jig extra vibrations to get the bassís attention. Also when fishing for bass in the spring during spawning season, you will notice that the bass are on nest and close to the shore. Therefore, it is important to be careful to approach the bass in a slow and soft manor. This will ensure that your motion will not send too many unnatural vibrations into the water. To many unnatural vibrations will cause the bass to flee and scare the other fish in the area.

Largemouth bass posses another sense of mechanoreception that is kind of like a cross between hearing and touch. "The organ responsible for this is the neuromast, a cluster of hair cells which have their hairs linked in a glob of jelly known as 'cupala'. All fish posses free neuromasts, which come in contact directly with the water. Most fish have a series of neuromasts not in direct contact with the water. These are arranged linearly and form the fishes lateral lines. A free neuromast gives the bass directional input" (Reference 3, 1997). The lateral line receives signals stimulated in a sequence, and gives the bass much more information (feeling the other fish around it for polarized schooling, and short-range prey detection 'the sense of distant touch').

Figure 2: This picture of the largemouth bass shows the bassís lateral line

(contains neuromasts).

In one study, they look at bass auditory psychophysics. In the fish psychophysics laboratory, they use classical, or Pavlovian, conditioning combined with modern psychophysical methods to quantitatively investigate the capacities of bass to detect, discriminate, and perceive simple and complex sounds (Reference 1, 1997). In these experiments, bass are conditioned to briefly reduce their gilling movements when a sound is presented, or when a ackground sound changes in intensity, frequency content, or temporal pattern (Reference 1, 1997). Measuring the gilling movements is a way to know that the fish has detected the sound or the change in sound presented. Past and ongoing experiments have determined that bass:

1. can be as sensitive to sound as all other vertebrates studied,

2. hear primarily in a low-frequency range, from below 40 Hz to about 2500 Hz,

3. are able to discriminate differences in sound intensity and frequency as well as many

other vertebrate animals,

  1. have mechanisms for enhancing the processing of simple sound signals when
listening in noisy environments, 5. can perceptually segregate and recognize signals even when they are heard in a

complex mixture of other signals,

(experiment setup and results from (Reference 1, 1997)).

Bass are also able classify complex sounds with respect to pitch, timbre, and temporal pattern. This latter ability is analogous to a person's ability to recognize the notes and rhythms played by a musical instrument, and to recognize the individual musical instruments playing the same note and rhythm.

Electricity: Electroreception


A set of pits comprise the electroreceptive system called the ampullae of Lorenzini. These are canals in the skin (extending along the long axis of the fish) filled with a gelatin-like material that also contain sensory cells (Encyclopaedia Britannica, 1980). Movements or disturbances near a bass change the voltage drop along the canals, which allows a bass to sense other organisms nearby (Encyclopaedia Britannica, 1980). They can detect muscular contractions of struggling prey in the surrounding water. This system is also a great aid for navigation in murky water.

How Senses Relate to Bassís Feeding Habits


Now, letís take a look at how these senses effect the feeding habits of bass. According to Fisheries Biologist Rich Cailteux, bass have a greater field of vision than humans and can see in all directions except directly behind or below. "The distance a bass sees will depend largely on water clarity," Cailteux emphasized ( Allen, 1997). "In low light conditions, they rely on other adaptations that sense sound or vibrations." ( Allen, 1997) Using "inner ear" structures and a highly developed lateral line system which occurs as a series of sensory pores along each side of the fish, a bass will respond to water movement by detecting the vibrations or sounds made by prey. This is a probable reason why rattling-type lures do so well in lakes where water clarity is poor. "Largemouth bass can also detect odors, but their use of smell or taste is not understood and probably used less for feeding than other senses," he stated ( Allen, 1997). Studies have shown that bass feeding habits change as they grow. After absorbing the yolk sac that supplies nourishment to the developing embryo (13 to 15 days after hatching), advanced bass fry begin to feed continuously on zooplankton, microscopic organisms that live suspended in the water. As they grow larger, aquatic insects and small fish become more prevalent in a bass diet, and by the time a fish reaches two or three inches in length (generally by late summer), they may feed almost exclusively on small fish and such larger crustaceans as grass shrimp and crayfish. "High mortality can occur during this life-stage due to a shortage of suitably sized prey," Cailteux said ( Allen, 1997). He goes on to add that bass feed predominantly on such things as threadfin shad, gizzard shad, bluegill, shellcrackers, golden shiners, smaller largemouth bass, and a variety of other small fishes ( Allen, 1997). Being opportunistic feeders that consume whatever is most readily available--frogs, salamanders, snakes, mice, turtles, and even birds are among items occasionally found in bass stomachs. Bass swallow organisms whole instead of biting off pieces, thus limiting the size of the prey they consume. Any prey having a body depth less than the diameter of the bass's mouth may be consumed. A bass will grasp its food any way it can, but usually tries to swallow other fish head first, thus forcing the dorsal fin of the prey to lie flat when swallowed. Cailteux pointed out that bass can be an "ambush predator" which lies in wait for prey to swim by ( Allen, 1997). "This type of behavior takes place when vegetation or other structure is available," he stressed ( Allen, 1997). "In open water situations, bass become active pursuers and, because of a streamlined shape and muscular body, allows them to outswim their prey." ( Allen, 1997) Although bass are usually considered to be solitary predators, they frequently gather in schools to "round up" such prey as shad. Feeding behavior of bass can be triggered by hunger or by reflex when something is introduced into its immediate environment. Anglers can trigger this reflex feeding response by presenting a lure within its field of vision. Adult largemouth bass do not feed continuously, said Cailteux ( Allen, 1997). "Once a meal is ingested, it may not feed again for hours or days depending upon the size of the prey that was eaten. In general, larger bass eat larger prey, so the time span between meals is usually longer." ( Allen, 1997)

So as you can see, senses to the largemouth bass are very important to there existence. Without there senses of sight, smell, touch, feel, taste, and electroreception, they would not be able to hunt there prey. With these senses the largemouth bass is an extremely effective hunter and game fish. These senses make the largemouth bass an extremely challenging fish to caught. If you are aware of their senses, you can use them to your advantage to make bass bite.


  1., 11/01/97.
  2. Allen, Herb., "Feeding Habits of Bass", 11/01/97.
  3., "How Do Fish Sense?", 11/01/97.
  4. The New Encyclopaedia Britannia Macropaedia, Encyclopaedia Britannica, inc., 1980, Volume 16, p.546.

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