LARVAL DEVELOPMENT OF NANNATHERINA-BALSTONI REGAN (NANNOPERCIDAE), WITH A DESCRIPTION OF ONTOGENIC CHANGES IN DIET

This article describes the larval development and ontogenetic changes in diet of Nannatherina balstoni and constitutes the first description of flexion and postflexion larvae for the family Nannopercidae. Larva e were collected from pools in southwestern Australia. Larvae are elon gate to moderately deep, lack head spines, have a moderate to large he ad and are moderately to heavily pigmented. Notochord flexion is compl ete by approximately 11 mml i.e,, longer than in members of the closel y related Percichthyidae (less than or equal to 9 mm). The sequence of fin completion, C, D-2, A, D-1 --> P-1 --> P-2, also differs to that reported for percichthyids,but is the generalized condition within the percoids. The retention of a prominent notochord tip in postflexion l arvae of N. balstoni is a characteristic that occurs in few teleosts. Nannatherina balstoni exhibits marked ontogenetic changes in diet. Lar vae feed predominantly on cladocerans, copepods and dipteran larvae, w hereas juveniles and adults ingest a large proportion of terrestrial F auna.