Embryonic and larval development of Tridentiger trigonocephalus

Tridentiger trigonocephalus is widely distributed along the coast of the Pacific Ocean. There is no information about morphological feature of their early life. Embryonic and larval development of T. trigonocephalus were studied in this paper. The results indicated that the fertilized eggs of T. trigonocephalus were spherical in shape,and the diameter was (0.482-0.606)mm. The developmental time of 25 embryonic developmental stages were described in great detail from fertilization to hatching. According to the morphological feature,the embryonic development of Tridentiger trigonocephalus were divided into 7 stages,including the fertilized egg and the blastoderm form stage,the cleavage stage,the blastula stage,the gastrula stage,the neural stage,the organogenesis stage as well as the hatching stage. Under the water of temperature (21.5±1.0)℃, salinity 4.0,pH (7.2-7.5),the embryonic development required at least 160 h . The starting time of seven stages of embryonic development were as follows:the fertilized egg and the blastoderm form stage was at 0 h post fertilization (pf). The cleavage stage was at 2 h 10 min post fertilization (pf). The blastula stage was at 6 h 50 min post fertilization (pf). The gastrula stage was at 14 h30 min post fertilization (pf). The neural stage was at 22 h 30 min post fertilization (pf). The organogenesis stage was at 27 h post fertilization (pf). The hatching stage was at 150 h post fertilization (pf). It spent more time from heart beating to hatching than other stages,which covered 56 percent of the time of embryonic development. Meanwhile pectoral fin,kidney and bladder came into being before pre-stage of hatching stage. The larva was (2.534±0.078)mm in total length. In the water of temperature(21.5±1.0)℃,yolk sac disappeared in five days after hatching and the stage of larval development was finished. It formed peptic structure,athletic structure and metabolizing structure in the stage of larval development.