Larval development of Nannatherina balstoni Regan (Nannopercidae), with a description of ontogenetic changes in diet

Abstract

Abstract— 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. Larvae were collected from pools in southwestern Australia. Larvae are elongate to moderately deep, lack head spines, have a moderate to large head and are moderately to heavily pigmented. Notochord flexion is complete by approximately 11 mm, i. e., longer than in members of the closely related Percichthyidae (≤ 9 mm). The sequence of fin completion, C, D2, A, D 1→P1→P2, also differs to that reported for percichthyids, but is the generalized condition within the percoids. The retention of a prominent notochord tip in postflexion larvae of N. balstoni is a characteristic that occurs in few teleosts. Nannatherina balstoni exhibits marked ontogenetic changes in diet. Larvae feed predominantly on cladocerans, copepods and dipteran larvae, whereas juveniles and adults ingest a large proportion of terrestrial fauna.