1. Development of Amphioctopus fangsiao (Mollusca: Cephalopoda) from eggs to hatchlings: indications for the embryonic developmental management.
Jiang, D., Zheng, X., Qian, Y., & Zhang, Q. (2020). Marine Life Science & Technology, 2(1), 24-30.
Amphioctopus fangsiao is an important fishery resource in northern coastal China, and there is an interest to develop its commercial cultivation under controlled conditions. In this study, we describe the embryonic development of A. fangsiao from eggs to hatchlings, focusing on the formation of the mantle, eyes and arms. Results indicate that this species has several favorable characteristics for aquaculture, such as a short incubation period and a large body size of hatchlings. During the organogenesis, the primordia of organs, including the optic sac and arm crown, first appeared at stage VIII; then the mantle primordium, eye primordia and arm crown become visible at stage IX–X, and the rudiment of embryo (mantle, eyes and arms) was completely outlined at stage XI. The retinal pigment appeared yellowish at stage X–XI and gradually deepens in pigmentation in the subsequent stages, turning from yellowish to yellow, red, dark-red and eventually black. At stage XV, the primary lid fold, with only a circular opening remaining, covered the eye, and the dorsal ocular edge did not reach the ventral side until hatching (day 1–7). Afterwards, about 24 days after hatching, both the dorsal and ventral sides of eyelid could contract freely, with an oval and elongate slit remaining that was a miniature version of the adult morphology. The chromatophores and ink sac appeared at stage XIV. These observations provide a foundation for the reproductive biology and aquaculture of A. fangsiao and also offer an important reference for the research of embryonic development in related species.
2. Laboratory growth, feeding, oxygen consumption and ammonia excretion of Octopus ocellatus.
Segawa, S., & Nomoto, A. (2002). Bulletin of Marine Science, 71(2), 801-813.
Hatchlings from eggs spawned by a female Octopus ocellatus were reared individually in closed seawater systems to make precise analyses of their daily amount of feeding, growth, oxygen consumption and ammonia excretion over the life span at 20°C and 25°C. Octopuses were fed with live hermit crabs. After about 120 d of rearing, hatchlings of about 0.11 g grew to 16.1 ± 7.4 g at 20°C and 18.6 ± 13.1 g at 25°C, respectively. Mean instantaneous growth rates in weight for the first 25 d were higher at 25°C, 8.3 ± 2.3%, than 20°C, 5.6 ± 2.5%, and both rates declined to about 1.0% after 100 d. Mean feeding rate at 20 d post-hatching was 30% of body weight per day and declining to less than 7% after 100 d. Feeding rate at 25°C was significantly higher than that of 20°C during the first 50 d. Oxygen consumption rates for individuals increased with increasing wet weight, and were slightly higher at 25°C than those at 20°C for animals less than about 3 g in wet weight. Growth rate, feeding level and oxygen consumption rate were sensitive to temperature in the early life period during the first 50 d. Without copulation two females spawned unfertilized eggs at 135 d after hatching (14.17 g) at 20°C and 152 d (7.68 g) at 25°C, respectively. The life span of O. ocellatus was estimated to be 6 mo to 1 yr depending on geographic location.
3. A comparison of the fatty acid profiles of newly hatched, fed, and starved juveniles of Amphioctopus fangsiao (d’Orbigny 1839).
Tziouveli, V., & Yokoyama, S. (2017). Aquaculture International, 25(4), 1531-1542.
The paper provides a first look into the fatty acids (FA) of young Amphioctopus fangsiao. Laboratory-hatched, 1-day-old juveniles (NH) were analyzed to identify the basal FA profile. To determine dietary effects on FA, individually kept juveniles (FD) were fed mysids once daily. Others were subjected to starvation (ST) to examine which FA may be used and which would be conserved. Treatments run for 25 days post-hatch, at which time ST and FD were analyzed to record FA changes. The dominant FA were 16:0, eicosapentaenoic (EPA), and docosahexaenoic (DHA), overall accounting for 40–60%. Monounsaturated FA (MUFA) were the highest in FD at 24.2% whereas highly unsaturated FA (HUFA) were most prominent in ST at 45.5%, followed by NH at 40.2%. Among n-3 HUFA, DHA was dominant in ST at 22.9 mg g−1 dry weight (DW), the role assumed by EPA in FD at 11.5 mg g−1 DW. Consequently, the DHA/EPA ratio was the lowest in FD. Arachidonic was the most abundant n-6 HUFA, representing >5% in total FA. However, n-6 FA were not prevalent, resulting in high n-3/n-6 in all juveniles. It could be argued that young A. fangsiao require n-3 HUFA, particularly DHA and EPA at a ratio of ideally >1.5 and to a lesser extent n-6 HUFA. Juveniles fed on a low lipid, high n-3 diet increased their MUFA content while maintaining high HUFA. Despite changes in the FA of ST individuals, it appears food-deprived A. fangsiao do not depend on FA mobilization for energy production.