Adaptations

The black crappie has a variety of adaptations that allow it to thrive in its habitat. For example, Pomoxis nigromaculatus has two main adaptations that allow free movement without unnecessary expenditure of energy. The body of the black crappie is very flat, which minimizes the surface area exposed to water. This reduces friction and resistance, helping the organism to move faster and with ease. The swim bladder also helps Pomoxis nigromaculatus to conserve energy. This organ contains gas and creates natural buoyancy, which allows the black crappie to remain motionless in the water and swim more effortlessly. The pressure inside of the swim bladder can change according to the depth that the black crappie is swimming. Both of these adaptations have improved the locomotion of Pomoxis nigromaculatus.

The internal gills of the black crappie are another important adaptation. This structure aids in both respiration and feeding. The gills increase surface area for the uptake of oxygen and also serve as a site for filter feeding. As a result, black crappies consume zooplankton as a main part of their diets. Once food is filtered to the gills, it passes directly to the stomach, which allows for efficient digestion. There is also a small flap called the operculum over the gills that helps to maintain continual water flow through the gills.

To learn more about the black crappie’s nutrition, click here.

Because black crappies rely primarily on sight to feed, they have large, well-developed eyes. The lens is spherical and actually protrudes through the pupil, which is very dissimilar to human eyes. This protrusion allows Pomoxis
nigromaculatus to have an extremely wide field of view,
which improves peripheral vision and allows for more
efficient predation. The eyes also have special adipose
eyelids that protect the eyes from harm as the black
crappie moves swiftly through the water. Both of these
adaptations have helped Pomoxis nigromaculatus
become a successful predator. This photograph shows how fish would view this
scene. Photo by Tim Morris. To learn more about the black crappie’s interactions with other species, click here.

Pomoxis nigromaculatus also has an important adaptation in its reproductive cycle. Individuals do not begin to spawn until late spring, which ensures that the young black crappies will mature in time for the winter. They will have been alive long enough to learn to catch prey and evade predators. This increases the chance of survival among members of the new generation. All of these adaptations have allowed the black crappie to live successfully in freshwater lakes and streams throughout the United States.

To learn more about the black crappie’s nutrition, click here.
To learn more about other fascinating organisms that live in the La Crosse area, click here.