Development of embryos and larvae of Portunus trituberculatus (Decapoda, Brachyura) in off-season breeding mode
2021
Studying the development of embryos and larvae is vital in the understanding of crab biology, which is helpful for the smooth progression of crab culture. The development of embryos and larvae of Portunus trituberculatus under the off-season breeding mode was studied in this paper. The results showed that the embryonic development of P. trituberculatus could be divided into nine stages: zygote, cleavage, blastocyst, gastrula, nauplius, metanauplius, protozoea, prehatching stage and hatching stage. The colour of each stage was yellow, orange-yellow, orange-yellow, orange-yellow, orange, orange, jacinth, dark grey and black, respectively. When the water temperature and salinity were 28.6 ± 0.7°C and 26.3 ± 0.4, respectively, the embryonic development time was 180 hours and the effective accumulated temperature reached 4248 h · °C. Larval development went through a zoea and a megalopa phase. The zoeae can be divided into stage I zoea (Z₁), stage II zoea (Z₂), stage III zoea (Z₃) and stage IV zoea (Z₄). Under the conditions of a temperature of 29.7 ± 1.3°C and a salinity of 26.1 ± 0.2, it only took about 12 days from hatching to the development of a stage I juvenile crab (C₁). In this study, it was found that the embryos and larvae could develop normally under the conditions of high temperature, and the breeding time was greatly shortened. Therefore, the off-season breeding and cultivation were considered promising for the aquaculture of this crab.
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