Morphology of the complete embryonic and larval development of commercially important mud crab Scylla paramamosain

Mud crab, Scylla paramamosain, is an important aquaculture species. In recent decades, with the development of mud crab farming, seed production has become more and more important. Therefore, a precise understanding of embryonic and larval development is required for future study or application. In this study, we described the complete embryonic and larval development of S. paramamosain under the following conditions: temperature 28 degrees C-31 degrees C, salinity 26,000-30,000 mg/L, pH 7.9-8.2, and dissolved oxygen 4-5 mg/L. The embryonic development was divided into five stages: cleavage, blastula, appendage, eyespot-heartbeat, and prehatching. The entire embryonic period spanned 9-11 days. The larval development consisted of six stages: zoea I (Z1), zoea II (Z2), zoea III (Z3), zoea IV (Z4), zoea V (Z5), and the megalopal stage. The duration of the larval stage was about 22-24 days, and it took about 3 days for each stage of Z1-Z4, about 4-5 days for Z5, and about 5-6 days for the megalopal stage. In general, in this study, we presented a comprehensive description of both embryonic and larval development with massive image information, which would help diagnose different developmental stages and provide an important guidance for future study or application.