Bruggemann also further studied the difference in the foraging behavior of the juveniles and adults of the two species S. vetula and S. viride. The adult and juvenile forms of Scarus vetula did not leave any grazing scars behind. The adult form of Sparisoma viride left behind large grazing scars, but the juvenile of this species did not. Competition between the two species for food sources, endolithic and macro algae, is relatively low because each species utilizes these food resources differently and grazes on these types of algae in very different places. Parrotfish have a diverse social and sexual behavior that includes territorial and non-territorial groups.
Territorial groups consist of one supermale or terminal male and one to three females.
Parrotfish are hermaphroditic and usually begin life as females. As the fish grow larger and territory becomes available, some will mature into super-males. Transitional males that do not defend a territory show secondary sexual characteristics in the form of secondary testes. These functional groups can be further diversified among species and range from a monochromatic society that is strictly a monandric species in which males, predominantly supermales, are permanently territorial, to a dichromatic society which is diandric and in which males only hold a territory for a short period of time. These distinctions have even been seen between different populations of the same species.