Luxilus cornutus - BIO203
The Shiner's Common Habitat
Luxilus cornutus is a freshwater fish that is most commonly
found in the midwest in nearly all water bodies, including streams,
rivers, and inland lakes. Because the common shiner is just so common,
there are not too many restrictions on it's habitat that it occupies.
One situation that does change the basic habitat observed is what life
stage the minnow is in. The three main life stages for a fish are the
embryo, fry or juvenile, and the adult. To learn more about the embryo
and reproduction, click here.
The embryo of the fish is found mainly in sand or gravel over which there is a constant flow of water. If possible, the embryos are placed in an area that produces an eddy (click here to see a short clip of what an eddy looks like). An eddy is a region that has the water moving in a direction opposite to that of the main current, especially in a circular motion. This eddy will cause an increase in water circulation, prevent the area from becoming filled with silt, and a great increase in oxygen availability.
The fry, or juvenile, minnow will leave the nest area and usually form small schools. Once together, they will congregate near the surface in calm pool areas. Occasionally the fry will venture into faster water until they are more grown and able to withstand the increased current.
The adult shiner will occupy a very diverse range of habitats. The
most common, however, are in small to medium sized streams with clear,
cool water and a moderate current. They live over a diverse type of
bottom, including sand, rubble and even gravel. One vital aspect of the
habitat, however, is that a pH in the range of 6.5-8.5 is considered
essential for proper growth. A pH out of this range results in a large
decrease in the shiner population.
The common shiner is known to occupy the lowest third of the water
column in the absence of a predator but are found nearly everywhere when
they are trying to escape from being another organism's meal.
The
common shiner was found to occupy cover for protection only 55% of the time,
whether avoiding a predator or not. This is different compared to most
other types of minnows that increase use of cover dramatically during times of
stress. Another behavior exhibited by the common shiner is that it will
not move out of the pool and into riffles in the presence of a predator
where nearly all other minnows will. These few pieces of evidence that
the common shiner takes less precaution during times of danger is not
understood fully. One thought to why this occurs, however, is that the
common shiner is generally larger than most other minnows and thus may
be able to escape predators easier without the use of cover.
Go back home, or continue to learn about some fish anatomy.