The Comparative Morphology of the Pectoral Free Rays in Scorpaenoid Fishes (perciformes: Scorpaenoidea))

The pectoral fins of many benthic taxa have evolved many unique features used to interact with the substrate. In one such group, the searobins (Triglidae: Scorpaenoidea), three of the pectoral fin rays have become separated from the fin as a whole, allowing them to operate as a separate appendage from the fin as a whole. The anatomical structure of these \u22free rays\u22 was investigated and several previously unreported muscle and bone variations were found. This method was extended to include members of four other scorpaenoid families which possess free rays, which revealed important differences in the muscle, bone, and nervous structure of this trait. Geometric morphometric analysis of major free ray components displays family specific patterns in the attachment of muscles and shape of bone processes. The anatomical diversity of this trait suggests that it has evolved multiple times and has taken on unique specialized roles in each taxon