Development of the Laterophysic Connection

We have described the ontogeny of the laterophysic connection in tholichthys larvae, juveniles and adults of Chaetodon ocellatus.  Individuals of this species, which stray northward with the Gulf Stream, were collected in minnow traps at the Rutgers University Marine Field Station (Tuckerton, NJ).  Tholichthys, juveniles and adults (14.5-73 mm SL) were prepared histologically (embedded in plastic resin, sectioned at 5 µm and stained with cresyl violet) in order to describe the pattern and timing of the development of the different components that define the laterophysic connection.  The medial opening of the supracleithrum and an inflated swim bladder with small outpocketings in the anterior swim bladder wall are already present in the smallest specimens examined (15 mm SL tholichthys). Transformation to the benthic juvenile stage (loss of cranial plates characteristic of tholichthys) is complete in individuals of 24 mm SL and cylindrical horns extending rostrally from the swim bladder are apparent in individuals >25 mm SL.   The proximity of the body of the air-filled swim bladder to the medial opening is established during the larval stage and proximity of the the volume of air inside the swim bladder horns with the opening in the supracleithrum is maintained as the swim bladder horns elongate just after transformation.  This study provides morphological evidence for potential ontogenetic changes in sensory capabilities, and discusses the potential importance of sensory input in transforming individuals and the developmental basis for the evolution of the laterophysic connection.

This study was carried out by undergraduates Natasha Kelly and Nicole Cicchino who worked as a team in the Webb lab for three years.  This work was presented at ASIH in 2001 and has been submitted for publication.

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