| Octopus minor (Sasaki,1920) is distributed widely in the coastal waters of Chinaand has become an important economic cephalopod in the north of China. The studieson cultural of the life cycle of Octopus minor will be useful to its resource protection,restoration and new mariculture species development.The paper aimed at Octopus minor located in the coastal waters of Rizhao,Rongcheng of Shandong Province and Ganyu of Jiangsu Province. The culture of thelife cycle of the species is including that: artificial temporary culture indoors, matingand spawning of parents, larval breeding, ongrowing and overwintering culture. Themain results are following:Firstly, overwintering culture of Octopus minor was carried out from November2011to April2012. Bivalve mollusks were the main food to feed. The survival rate ofO.minor reached50%during this period. The fertilized eggs were obtained in June2012.Secondly, Artificial reproduction, larval breeding, ongrowing and culture of thespecies were carried out from2011-2013.More than2000individuals of undamaged Octopus minor with healthy color andfull of gonad were selected and transported into temporary pool indoors from May toJuly in2011-2013. Some kinds of shields were put in the bottom of the pool for parentshield and spawning. Octopus minor ate crab, clamworm and frozen fresh shrimp inpromoting mature stage. After mating in a period of time, the female octopuses laideggs in the artificial nests. The egg laying amount ranged from30to120. Afterspawning, the artificial nests were sealed with nets and transferred to hatching pools.During the hatching period, each female was fed on crab. The light intensity alwayskept less than500lx.The mean total length of the just hatched larvae was about3cm and the weightranged from0.2g to0.3g. As the initial food, crab, Artemia, gammarid and clam meat were fed, respectively. The best diet for larvae was small crab(2-3mm).With thedevelopment of larvae, the size of crab fed should be increased. After140days,Ruditapes philippinarum were fed. After237days cultivation, the weight of adultOctopus minor reached to28.9g (♂),21.2g (♀), respectively.Thirdly, The studies on biological zero temperature and effective accumulatedtemperature for embryonic development of Octopus minor were also carried out underthe artificial conditions. The hatching of the fertilized egg last77days and87days inthe average temperature of23.19℃and20.96℃, respectively. The results showed thebiological zero temperature of embryonic development of Octopus minor was3.79℃and the effective accumulated temperature was1494℃·d. Meanwhile, embryonicoverwintering breeding of Octopus minor was done from July2012to March2013under the natural seawater temperature of0℃to25.7℃. The results showed theembryonic development could stop when temperature decreased below the biologicalzero temperature and the embryo could tolerate0℃or so. Once the temperatureincreases beyond the biological zero temperature, the embryonic development couldresume, and egg could also hatch as usual. |
