ABSTRACT
The heads of parrotfishes possess distinctive features that enable them to feed on the algae, bacterial mats, and other materials that encrust calcareous and rocky reef surfaces. Using five sympatric species of parrotfishes within two genera (Scarus and Nicholsina) that inhabit the Gulf of California as foci, this chapter chapter discusses the details of the head anatomy of that enable these fishes to consume a diet that includes massive amounts of abrasive substrate scraped from resistant surfaces. Facilitating this behavior are oral jaws that constantly regenerate through replacement of tiny teeth. The jaws contain durable ligaments that resist stresses, are shortened to enhance their mechanical advantage, and contain a mandible that includes a noteworthy second joint at its midpoint. The positioning of the muscles that contribute to the jaw apparatus are interpreted as is the architecture of the skeleton that accommodates the musculature, joints, levers, and connective tissue elements. Among these features are cruciate ligaments, serrated joints, menisci, and a specialized elastic ligament interconnecting the ascending process of the premaxilla of the upper jaw with the braincase.
