Why the Round Head? Morphometrics relating to Ontogeny of Select Bulbous Fishes

Abstract

Potential effects of changing body shape morphometrics with growth in bulbous fishes were studied in five species; Clinocottus globiceps, Oligocottus maculosus, Liparis dennyi and Gobiesox maeandricus and Chitonotus pugetensis, all found and collected in the Salish Sea, Washington. For each species there was a size range that attempted to encompass juvenile to adult forms. We evaluated the standard length, body width and body depth along the length of the body of each individual. To understand how body streamlining and structural stiffness change with growth we calculated second moment of area and aspect ratio. We found a significant correlation between ontogeny and change in body shape and stiffness. As these fish grow in length they become more streamlined along the body and increase stiffness of their wide heads. Changing body morphometrics with growth have important implications about fish’s swimming performance, predator avoidance, obtaining food and maneuvering within their habitat.