DEVELOPMENT OF THE VERTEBRAL COLUMN AND THE PECTORAL AND CAUDAL FINS IN LARVAE OF THE LARGE YELLOW CROAKER LARIMICHTHYS CROCEA (RICHARDSON)

The large yellow croaker Larimichthys crocea, one of the most commercially important marine fish in China, has been widely cultured in the South China Sea due to the success of artificial propagation in 1990s. Information about embryonic and morphological developments of larvae of this species is available, but little is known about its osteological development. In order to obtain the knowledge of the normal onset of skeletal structures throughout development, the developmental pattern of the vertebral column and the pectoral and caudal fins in larvae (3-28 days after hatching) of the cultured large yellow croacker Larimichthys crocea was studied. 50 specimens per day were collected and fixed in 5% formalin solution after measuring individual total length for later staining. Specimens were stained with alcian blue and alizarin red and observed for skeletal development. The results showed that larval notochord appeared segment at 6 d.a.h (MTL3.9mm). The vertebral column was formed at 14 d.a.h (MTL7.5mm) and then ossified by 28 d.a.h (MTL19.5mm). The supracleithrum, cleithrum, postcleithrum and the fin plate of the pectoral fin appeared right after hatching, and developed completely with five pieces of proximal pterygrophores and numbers of lepidotrichium at 27 d.a.h (MTL19.0mm). The development of the caudal fin began with the formation of the hypural at 8 d.a.h and well developed with three pieces of epural and five pieces of hypural that enclose the urostyle as well as lepidotrichia. The urostyle and lepidotrichia was fully ossified by 28 d.a.h.