Meeting Abstract
Fish scales are bony plates that cover the body of fishes in overlapping patterns. Most past work on fish scales used two-dimensional microscopy to qualitatively study structural features. Although valuable in describing major features of scale diversity, a full understanding of the form and function of scales requires study of their three-dimensional (3D) morphology and surface patterning. 3D morphology both increases our knowledge of the morphological diversity of fish scales, and also helps inform possible functions, such as protection and drag reduction. To that end, we have imaged and quantified 3D fish scale morphology in detail in single species, across species, and in vivo. Our results reveal considerable previously unrecognized scale variability both within and among species. Furthermore, our in vivo measurements of scale topography demonstrate that mucus and epidermis have the potential to greatly alter surface topography, with implications for the hydrodynamic function of fish skin surfaces. Preliminary analyses of flow over fish scales with and without mucus indicate that mucus changes near-surface flows in ways that reduce drag. We also present comparative surface topography data from 59 species of damselfishes and provide the first evidence that scale morphology responds adaptively to ecologically driven selection. Altogether, we argue that scales represent an important but largely unexplored axis of functional and morphological diversity in bony fishes. Our morphological, comparative, and functional data combine to portray the interactions between scales and mucus as well as their function and ecology to build a foundation for understanding the vast diversity of fish scales.
