Meeting Abstract

P3.100  Friday, Jan. 6  Modeling feeding biomechanics of the asymmetrical flatfish Paralichthys lethostigma HENSON, C.B.*; FRANCIS, JR., A.W.; Armstrong Atlantic State Univ., Savannah, GA

The vast majority of bony fishes are characterized as being symmetrical morphologically, and due to this, most observations can be made solely from the sinistral side. However, flatfishes (Order Pleuronectiformes) have an obvious asymmetry that results from the migration of one of the eyes to the opposite side. This study examined whether or not any asymmetries in the morphometric features of southern flounder, Paralichthys lethostigma, affect the design and function of the feeding mechanisms. P. lethostigma were collected by seine net, hook and line, or aquaculture facilities. For each fish, the lower jaw and associated muscles were extracted from fixed individuals of the species. Using digital photographs of the jaws, measurements were made of the opening and closing in-levers, out-lever, length of the adductor mandibulae muscle, dorsal and ventral jaw length, as well as the distance from the origin of the adductor mandibulae muscle to the articulate joint. These measurements were then entered into jaw simulation software to determine mechanical advantage of jaw opening and closing as well as properties of the adductor mandibulae muscle. Using these measurements and calculations, comparisons were made of the ocular side versus the blind side for any apparent asymmetrical relationships. The results of the P. lethostigma specimen were also compared to another flatfish species with differing lifestyle and diet in order to identify any evidence of an evolutionary trend. The relationships of both the morphometric features and the biomechanics of the lower jaw indicate that the observed asymmetries in flatfishes do contribute to functional differences between the sides. Future research in this area will look at a larger size range of specimens as well as making additonal comparisons with other members of the order.