Meeting Abstract
71.5 Jan. 7 Patterns of cranial skeleton ontogeny in Syngnathidae: a comparison between Syngnathus rostellatus and Hippocampus capensis LEYSEN, Heleen*; JOUK, Philippe; ADRIAENS, Dominique; Ghent University; Antwerp Zoo; Ghent University heleen.leysen@ugent.be
The special reproductive strategies of Syngnathidae, their elongated snout without teeth, the fastest food intake among teleosts and the vertical position in the water column with the accompanying tilted head of seahorses, makes pipefishes and seahorses very remarkable. Despite their exceptional appearance little is known about their morphology and ontogeny. The aim of this research is to compare the ontogeny of the head skeleton in Syngnathus rostellatus and Hippocampus capensis. A detailed morphological study was performed using cleared and stained specimens, as well as serial histological sections for graphical 3D-reconstructions. The obtained results were compared with those of Gasterosteus aculeatus, which has a basal position within the same order. Based on the results of this study and data from literature it could be concluded that the elongation of the snout appears very early in the development. Already at the moment of being expelled from the brooding pouch, the juveniles are provided with a specialized feeding-apparatus, comparable to the adult situation. It could also be shown that there is a close resemblance between S. rostellatus and H. capensis, with the most important dissimilarities being related to the different levels of snout elongation. However, a distinct neurocranial dissimilarity was observed during early ontogeny, with the seahorse braincase being tilted with respect to the ethmoid region. The differences with G. aculeatus involve a series of structural specializations in S. rostellatus and H. capensis that can be related to powerful and fast suction feeding, such as the reduced maxillary bones without protrusion, the elongation of the ethmoid region to form the tubular snout and the well developed hyoid arch.
