Biology of Finfish and Shellfish (2+1)

Balistidae

• Larvae elongate and slightly compressed, but by 1.6mm(2.5 days post hatch) they are of moderate depth.
• Larvae initially round in the trunk but become laterally compressed during flexion, and have a slender, compressed tail.
• There are 18-19 myomeres (5-10+10-13). The gut is deep and coiled from the time of yolk absorption.
• A small, inconspicuous, gas bladder is located above the anterior portion of the gut.
• The head is moderate to large prior to flexion and large following flexion.
• The mouth is small and terminal.
• The large eye is round, and becomes moderate in the juvenile stage.
• Head spination is a tuft of spinules on the preopercle that form by the time the eyes are fully pigmented (approx. 1.5mm, 2.5 days after hatching).
• The tuft of spinules disappears just prior to or during the early flexion stage in conjunction with appearance of spinule-like scales on the head and body.
• Spines 1 and 2 of the dorsal fin are the first fin elements to form, first projecting above the finfold at about 3mm. Incipient soft rays in the dorsal and anal fins are present at the start of flexion as in dorsal spine 3.
• Pectoral fin rays begin to form during flexion.
• Balistid larvae have a heavy pigment on top of the head and nape and over the gut and operculum.
• There is a series of melanphores on the ventral midline of the tail which often extends around the notochord tip to the dorsal midline.