Woodard, A.*; Shardo, J.: Morphological changes associated with the development of feeding in red snapper (Lutjanus campechanus).

The formation of a functional feeding apparatus in larval teleosts is a finely tuned, functionally integrated set of processes. We examined the formation of the feeding apparatus in the larval red snapper from hatching (22 hr postfertilization) through mouth formation (70 hr pf). Two developmental series were collected (1997 and 2000) at the Claude Peete Mariculture Center (Alabama Marine Resource Division, Gulf Shores) and examined using scanning electron microscopy and clear and stain techniques. At hatching (22-25 hr pf) the head has not lifted from the yolk and the larvae are lacking all basic feeding structures. The larvae do not show signs of mouth cavitation, nor jaw or visceral arch formation, and the head remains attached to the yolk ventrally. As posthatch development continues and the head enlarges the yolk sac underlying the head recedes exposing the ventral surface of the head (36-50 hr pf). The single oil droplet moves caudally with the receding yolk sac. Visceral arches form posterior to the optic vesicles on the ventrolateral surface of the larvae, while the pharynx expands both anteriorly and laterally (~50 hr pf). At about 60 hr pf the mandibular arch splits and begins to reorganize into upper and lower jaws (70 hr pf). In conjunction with the complete adsorption of the yolk sac the stomodeum parts and the oral opening and the pharynx are connected. Prior to complete adsorption of the yolk the mandibular arch and associated mouthparts must become functionally integrated. This work supported through the Evaluation of Artificial Reef Modules (C900040005) to Robert L. Shipp and NSF grant DEB-9707530 to Judith Shardo.