FRANCIS, JR., A.W.*; TURINGAN, R.G.: Ontogeny of Feeding Kinematics in Southern Flounder, Paralichthys lethostigma

Fish experience a number of morphological and behavioral changes through ontogeny that may have consequences for feeding performance. For pleuronectiform fishes, ontogenetic changes in functional morphology may correlate with transition from endogenous to exogenous feeding, pelagic to benthic life style, and bilaterally symmetrical to asymmetrical morphology. Each of these transitions may be expected to constrain function. To asses the role of development on function, feeding kinematics of southern flounder, Paralichthys lethostigma, were recorded using high-speed video. Prior to metamorphosis, feeding kinematics were restricted to unilateral filming. Both during and following metamorphosis, feeding kinematics included simultaneous bilateral filming with an additional dorsal or ventral view. Both paired (ocular and blind sides) and unpaired kinematic variables reflecting excursions, angles, and timing of feeding structures were recorded. Preparatory, expansive, compressive, and recovery phases of the gape cycle were observed at all developmental stages. First feeding larvae had pronounced hyoid excursions which may contribute to an increased functional gape. Premetamorphic and metamorphic larvae had reduced hyoid excursions, but were capable of generating suction forces as observed by particle and prey movements during the gape cycle. Larval fishes also exhibited lateral head movements and sudden locomotor positioning movements which either drew prey closer or positioned the fish closer to prey. Observed changes in functional morphology correspond to reported hyoid and opercular developmental periods. Results presented here and by others on feeding performance are expected to help resolve the link between morphological development, survival, and feeding ecology.