Meeting Abstract

P1.59  Sunday, Jan. 4  Stress distribution and morphological specializations in the feeding apparatus of a seahorse (Syngnathidae: Hippocampus reidi) LEYSEN, H.*; DUMONT, E.R.; ADRIAENS, D.; Ghent University, Belgium; Univ. of Massachusetts, Amherst; Ghent University, Belgium heleen.leysen@ugent.be

The family Syngnathidae (Gasterosteiformes) encompasses the pipefishes and seahorses. Syngnathid fishes are characterized by an elongated snout with small terminal jaws. They are extremely fast suction feeders, with a feeding strike characterized by a rapid neurocranial elevation accompanied by an equally rapid retraction of the hyoid. This results in prey capture times of even less than 6 ms. However, the long, tubular snout with small diameter also has its disadvantages, including a limitation on prey size and an increase in the moment of inertia of the head during dorso-rotation. Our longterm goal is to investigate the degree to which the extreme morphological specialization of the feeding system in syngnathids constrains its functional versatility. One of the limitations that the feeding apparatus may experience is that of mechanical overloading during the extreme accelerations of skeletal elements and the production of high suction forces. Since expansion of the buccal cavity generates a large negative pressure, this implies that a great amount of mechanical force is exerted onto the head. We completed a finite element analysis of the skull of Hippocampus reidi to determine where stress accumulates under the strong pressure generated during suction feeding. We hypothesized that structural adaptations would be present in regions of high loading, in order to dissipate stress and avoid skeletal damage. A thorough histological and morphological study of the regions and bones that are experiencing the largest mechanical stress during suction feeding, allowed us to test this hypothesis.