The laterophysic connection and swim bladder of butterflyfishes in the genus Chaetodon (Perciformes: Chaetodontidae)


  • Jacqueline F. Webb,

    Corresponding author
    1. Department of Biology, Villanova University, Villanova, Pennsylvania 19085
    • Department of Biological Sciences, University of Rhode Island, 100 Flagg Road, Kingston, RI 02881
    Search for more papers by this author
  • W. Leo Smith,

    1. Department of Biology, Villanova University, Villanova, Pennsylvania 19085
    2. Department of Ichthyology, American Museum of Natural History, New York, New York 10024
    3. Center for Environmental Research and Conservation, Columbia University, New York, New York 10027
    Search for more papers by this author
  • Darlene R. Ketten

    1. Department of Biology, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543
    2. Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts
    Search for more papers by this author


The laterophysic connection (LC) is an association between bilaterally paired, anterior swim bladder extensions (horns) and medial openings in the supracleithral lateral line canals that diagnoses butterflyfishes in the genus Chaetodon. It has been hypothesized that the LC makes the lateral line system sensitive to sound pressure stimuli that are transmitted by the swim bladder horns and converted to fluid flow into the lateral line system via a laterophysic tympanum. The purpose of this study was to define variation in the morphology of the LC, swim bladder and swim bladder horns among 41 Chaetodon species from all 11 Chaetodon subgenera and a species from each of four non-Chaetodon genera using gross dissection, histological analysis as well as 2D or 3D CT (computed tomographic) imaging of live, anesthetized fishes. Our results demonstrate that the lateral line system appears rather unspecialized with well-ossified narrow canals in all species examined. Two LC types (direct and indirect), defined by whether or not the paired anterior swim bladder horns are in direct contact with a medial opening in the supracleithral lateral line canal, are found among species examined. Two variants on a direct LC and four variants of an indirect LC are defined by combinations of soft tissue anatomy (horn length [long/short] and width [wide/narrow], number of swim bladder chambers [one/two], and presence/absence of mucoid connective tissue in the medial opening in the supracleithrum). The combination of features defining each LC variant is predicted to have functional consequences for the bioacoustics of the system. These findings are consistent with the recent discovery that Chaetodon produce sounds during social interactions. The data presented here provide the comparative morphological context for the functional analysis of this novel swim bladder-lateral line connection. J. Morphol., 2006. © 2006 Wiley-Liss, Inc.