DEVELOPMENT OF THE VERTEBRAL COLUMN, FINS AND FIN SUPPORTS IN THE JAPANESE ANCHOVY, ENGRAULIS-JAPONICUS (CLUPEIFORMES, ENGRAULIDIDAE)

The ontogeny of the median and paired fins and their supports, the ver tebral column, predorsal bones, and pleural ribs of Engraulis japonicu s are described. A size series of 101 laboratory-reared specimens 2.3 mm NL to 37.3 mm SL from 0 to 59 days old, and an additional series of 181 wild-caught anchovy 1.5 mm NL to 110.6 mm SL were cleared and sta ined for both cartilage and bone. All fin supports form from cartilage in the following sequence: pectoral, caudal, dorsal, anal, and pelvic fin support. Completion of fins is in a different order. Almost all f in structures are present and partially ossified by the 51st day after hatching (ca. 24-27 mm SL). Caudal fin supports start development in 6.1 mm NL 9 day old larvae with chondrification of hypural 1 below the unflexed notochord. The anterior adult epural develops from two piece s of cartilage. Caudal fin rays develop from middle ones outward. Full complement of principal caudal rays is present in larvae >8.0 mm SL ( 11-20 days after hatching). Dorsal and anal fin anlagens appear in lar vae >6.2 mm SL. The enlarged first dorsal proximal radial originates f rom one piece of cartilage. A supernumerary dorsal distal radial devel ops behind the first distal radial. Left and right coraco-scapula cart ilages appear first fused ventromedially. Propterygium develops from t he pectoral radial plate. The pelvic scute originates from three scale -like pieces accounting for the lateral arms and the basal plate. Ossi fication of centra begins from 12.2 mm SL. Neural and haemal arches be gin chondrification by 7.3 mm SL. Twelve or 11 predorsal bones start t o chondrify posteriad by 15.8 mm SL in larvae 21 days old. Twenty four pairs of pleural ribs develop partially of cartilage and dermal origi n. Comparisons with other clupeiform species stress the necessity of f urther research in this fish group.