Pharyngeal jaw

Common card · No. 300627

Pharyngeal jaws are a "second set" of jaws contained within an animal's throat, or pharynx, distinct from the primary or oral jaws. They are believed to have originated as modified gill arches, in much the same way as oral jaws. Originally hypothesized to have evolved only once, current morphological and genetic analyses suggest at least two separate points of origin. Based on connections between musculoskeletal morphology and dentition, diet has been proposed as a main driver of the evolution of the pharyngeal jaw. A study conducted on cichlids showed that the pharyngeal jaws can undergo morphological changes in less than two years in response to their diet. Fish that ate hard-shelled prey had a robust jaw with molar-like teeth fit for crushing their durable prey. Fish that ate softer prey, on the other hand, exhibited a more slender jaw with thin, curved teeth used for tearing apart fleshy prey. These rapid changes are an example of phenotypic plasticity, wherein environmental factors...

Read on Wikipedia · Image Zina Deretsky, National Science Foundation (after Rita Mehta, UC Davis); Ryan Wilson (pbroks13), CC BY 3.0