Studies On Fundamental Biology And Artificial Reproductive Technique Of Octopus Vulgaris

Octopus vulgaris is mainly distributed in the coastal waters of southern China.As one of the important economic cephalopods, its export has been increasing little bylittle in resent years. Meanwhile, the increasing fishery catch pressure has resulted indrastic drop of natual resources. Therefore, the studies on fundamental biology andartificial reproduction of the species is of great importance to the protection andrational utilization of natual resources.This thesis studies the fundamental biology and breeding techniques forOctopus vulgaris in the southeast China sea. The basic biology study covered the armformula, embryo development and K lliker organ; while the breeding biologyincluded temporary culture of parents, spawning and egg caring, larva cultivation, andfeeds for various living stages. Based on these studies, breeding and culture techniqueof the speices builit up, which would serve as supports for factory culture andrestoration of natual resources. Here are the major achievements:() Basic biology1.The morphology data of the105Octopus vulgaris individuals captured in thesoutheast waters of Fujian Province in2010-2013. The results showed that the armformula was II>III> IV>I, except for the hectocotylized arm, there was no apparentdifference between the bilateral symmetric arms (p<0.05). There were enlargedsuckers on the2ndand3rdpair of arms of the male, usually the13thsucker. Most ofOctopus vulgaris were500-800g (70%of female and50%of males) weight in June,with some over900g (39.6%of males and18.1%of females).2. Octopus vulgaris was reared and bred indoors and its embryonic development andgrowth of paralarvae were observed. The morphological characteristics of differentembryonic stages were described. Sucker growth of paralarvae was illustrated using scanning electronic microscopy. The results showed that mature eggs were (2.4±0.2)mm in length and (1.2±0.1) mm in width. According to Naef (1928), the process ofembryonic development was divided into20stages, with twice reverses. Thedevelopment of fertilized eggs required25-35d before hatching at20.4-23.6. Theaverage length of newly hatched larvae was about3.08mm. The paralarval stage kept28-33d at the hatching temperature of25.2-22.8.3. K lliker organ of the paralarvae was observed by scanning electron microscopey.The organ looks like dot protuberance of40-in length located at the head, arms,funnel and pallium, with the most at the veutro of the head and the arm tips, taking6-7%of the surface of the pallium. The K lliker organ is composed of1400independent tube-like globule of in diameter.() Breeding techniques1The parents of Octopus vulgaris in spawning and protecting period were fed onMeretrix meretrix, Ruditapes philippinarum, Sinonovacula constrzct and Sebastodesfuscescens respectively. The effects of those diets about food intake, spawningnumbers, hatching rate of eggs laid as well as the size of newly hatching paralarvaewere investigated. The results showed that food intake per individual parent per day inorder was the average of19.50g in M.meretrix>18.28g in R. philippinarum>13.37gin S. constrzct>3.75g in S.fuscescens. The highest spawning amount of parents andhatching rate of fetilizated eggs was136,000and94.34%, respectively, whichoccurred in the group of R.philippinarum. The minimum spawning amount was98,900in the group of S.fuscescens, and the lowest of the hatching rate was81.11%in the control group. The average size of newly hatching paralarvae was2.43mm(R.philippinarum group)>2.39mm (M. meretrix and S. constrzct groups)>2.34mm(S.fuscescens group)>2.30mm (control group). During the period of spawning andprotecting, the food intake of O. vuglaris was about2%-5%of the weight ofthemselves, which improved hatching rate of egg laid and the size of newly hatchingparalarvae. R. philippinarum was the ideal food.2. The stuides on the breeding of Octopus vulgaris were carried out in2010-2013.Effects of initial feeds and light to the growth and survival rate of larvae were studied, and total length, mantle length, wet weight, dry weight as well as the growth of thesuckers were anylized. The newly-hatched larvae had the total length of2.76-3.06mmand led a plankton life. During the period, there was significant growth of arms, andthe change tendency of the number of suckers coincided the exponential function y=2.6611e0.2215x(R2=0.9869). The paralarvae ate Moina mongolica, Penaeus japonicusand artemia. The growth effection would be much better while crab larva were addedas supplement. The dry weight change tendency was y=0.1366e0.5968x(R2=0.9708).