Correspondence between shape and feeding habit changes throughout ontogeny of gilthead sea bream Sparus aurata L., 1758

The shape development through ontogeny of the gilthead sea bream Sparus aurata was studied by means of geometric morphometry and elliptic Fourier analysis. In parallel, observations are reported on the feeding habits of the same specimens until the end of the larval stage. Data for later stages were obtained from the literature. Sparus aurata underwent ontogenetic shifts in diet from zooplankton, selected by larvae, to mysids, errant polychaete, amphipods and isopods for juveniles, and finally to hard prey (decapods, gastropods and bivalves) in adults. The aims were: (1) to provide a complete description of shape development, from hatching to the adult stage, (2) to identify distinguishable morphological stages during ontogenesis, (3) to search for correspondence between morphological development and diet shifts, and (4) to examine the functional effect connecting shape changes to diet shifts and habitat selection. The growth trajectory obtained reflected a saturating curve made up by different sections. Each section corresponded to a developmental shape stage characterized by different allometric trends of different body regions. Indeed, these shape stages matched those based on widespread features of development. Furthermore, the size-defined limits of the shape stages closely match the feeding shifts in the development of dietary behaviour of gilthead sea bream. The different constraints underpinning this pattern of covariation are discussed by showing that the growth profile of early stages is mainly determined by organogenesis of important apparati, whereas that of later stages seems optimized to improve feeding on hard prey in complex microhabitat and swimming abilities, and to reduce predation risk. (C) The Authors Journal compilation (C) 2007 The Fisheries Society of the British Isles.