Nutrition

The pumpkinseed sunfish is found to mainly feed on mollusks, and more specifically, snails. They consume these snails by crushing them with their jaws. Many studies have been carried out to research the effects on different changes or pressures present on populations of Pumpkinseed sunfish. The percentage of snails in an individual's diet is directly proportional to the snail abundance in its habitat. In other words, as the number of snails increase in the individual's habitat the percentage of nails consumed also increases (Mittelbach, Osenberg and Wainwright 1992).

There is also a positive correlation with the mass of the jaw muscle, the levator posterior, and the percentage of snails in the diet. The jaw muscles and the bones used to help the individual crush its prey has been found to actually be smaller in those who live in snail-poor habitats than those who are located in snail-rich habitats. In fact, many times this main jaw muscle, the levator posterior, is found to be twice as big in the fish located in areas where there is a high abundance of snails than those who live in low abundance habitats. Also, the teeth are usually worn down in the fish that are in high abundance prey habitats due to the constant crushing of snails. The individuals who live in bodies of water with low snail abundance or are too small to consume snails tend feed more on insect larvae and other soft bodied invertebrates. Other observations show that the muscles and bones that are not used to crush prey exhibit no difference between high or low prey abundance populations (Mittelbach, Osenberg and Wainwright 1992).