They Did What?

Largemouth bass overcome environmental changes and have adapted to become very successful.  One reason why they are so successful is that they are not limited to one specific type of prey (see Nutrition).  They prey upon a number of species, and therefore maintain a healthy secure lifestyle.  Another adaptation that has allowed largemouth bass to become so well adaptive to different environmental conditions is their ability to withstand a greater change in water temperatures.  Largemouth bass can withstand warmer water temperature that has a lower concentration of oxygen gas available.  In comparison walleye need much colder water and a much higher oxygen concentration to live.  Optimal growth for largemouth bass occurs at a dissolved oxygen level at 5.0 ppm or above. Compared to walleyes that need around 9.0 ppm or above.


Mark and David Junge


An adaptation between the largemouth bass and the smallmouth bass a very close relative is the jaw size.  Yes, the largemouth bass has a larger mouth than the smallmouth bass.  To distinguish the differences between the two look at the closed mouth and if it extends beyond the eye it is a largemouth bass.  If it only extends to the middle of the eye it is a smallmouth bass.  This adaptation allows for a greater amount and size of prey to be consumed. 

                                      Mark Junge                                                                                                  


Largemouth bass perceive their environment through visual, auditory, and chemical means.  The lateral line which is located on the left and right side and runs from the gills to the base of the tail.  This lateral line is how they detect motion, sound waves, and helps with navigation.   See below for more information.



Interesting fact:

The record largemouth bass was 32 1/2 inches long, 28 1/2 inches around, 22 pounds 4 ounces and was caught in Montgomery Lake, Ga., in 1932.












External Anatomy

Eye: The eyes are located at the front part of the head.  The largemouth sees with its eyes and can detect color with them.  The eyes are located in such a way that they detect prey in front and above them. 

Nostrils: The nostrils are at the very front and are used to detect the faintest odors.  They also can be used to detect chemicals and toxins. 

Fins: The fins are used for movement and for protection.  The spiny dorsal fin is lined with spines that ray out from the back and can be used as a form of protection from predators.  Pelvic, anal, dorsal fins are all used for control and steering while the caudal fin is used for the power and thrust. 

Mouth: Where nutrients are taken in and connects to the stomach.   A trait that allows this species to consume a larger size of prey compared to its closest relative the smallmouth. 

Lateral Line: Used in detection of pressure changes in the water.  The Lateral line runs from the tail along both sides to around the eye.  This adaptation allows for detection of danger, and food capture. 

Scales: Scales cover the outside of the body of the bass providing protection from predators and the environment.  The scales are also covered in a mucus layer which aids in preventing infections. (Anglers must be careful not to remove the mucus layer if planning on releasing the fish).

Gills: Provide oxygen uptake for the bass.  The gill arches are unidirectional meaning that water flows in one direction over them.  The operculum protects the very sensitive gills.  Countercurrent exchange is the flow of water over the gill arches, blood flow comes from the opposite direction.  The countercurrent exchange sets up a diffusion gradient for the uptake of oxygen gas.

Internal Anatomy


Spine: Made up of many hollow vertebrae that run the horizontal length and house the spinal chord.

Spinal Cord: Nervous system controls helping in motor reflexes and muscle stimulation.  Also relays critical information from the brain to the rest of the body and vise versa.

Swim Bladder: A organ capable of filling and releasing air for controlling the bass' buoyancy.

Heart: Two chambered heart consisting of one atrium and one ventricle.  The heart then circulates blood through a closed circulatory system.

Kidney: Filtering waste products from the blood of the bass.

Brain: All sensory information is processed here and relayed electrical signals through the spinal chord and nerves to the body.


For more information on Largemouth Bass' anatomy


Now learn all about reproduction!