| This paper takes Hemifusus tuba as research subject. It researched the tissuestructure of the digestive and reproductive system of H.tuba by anatomical andhistological techniques. The aim is to understand the breeding way morphologicalstructure features, and feeding mechanism. We also carried out the artificial breeding,the juvenile nursery and explored the ways of propagation of H.tuba. All the resultsare as follows:1. Study on reproductive system and artificial breeding of H.tuba: Reproductivesystem of H.tuba was studied by anatomical and histological techniques. Andcombined with the artificial breeding trials, we can have a deeper understanding of itsreproductive biology.During anestrous season, the germen is thin and small volume. The testis isorange; Ovaries is white. During breeding season, the germen becomes more full andbig. The testis’ color deepened, ovary becomes sallow. Through penis and glandwrapped around the eggs we can distinguish the male and female. Though gonadsections, we can know that H.tuba have two breeding seasons in a year in westernGuangdong Sea; The results of artificial breeding showed that it is feasible of H.tubabreeding in winter in Dong，ao Island, Zhuhai city. The course of embryonicdevelopment occurs completely in egg capsule of H.tuba. It belongs to the directdevelopmental type. After hatching, it directly becomes naiad H.tuba and has no freelife stage of larva. The parents mate many times in a reproductive period. Mating timeis longer than a month. Because of the low water temperature in winter, the layingeggs at a slower speed. Average speed is0.5per hour. It needs45to50days to finishembryonic development under16.5to24℃, and it has a higher hatched rate.2. The Juvenile nursery: The feeding habits of naiad H. tuba in different stages,exposed to air resistance in the dry ability, effects of different sediment, intermediateculture in sea area were studied during April and August,2011.1). The results offeeding habits were as follows: under the temperature17～20.5℃conditions, juvenileH. tuba can active feeding fresh baits （Oyster, clam） after7days. In the first7days,the growth in shell height is0.34mm·d-1, growth in shell width is0.11mm·d-1, increasethe weight is0.0024g·d-1. Feeding live baits, shell high growth rate is0.417mm·d-1,wide growth rate is0.17mm·d-1, increase individual weight is0.01g·d-1;2). The results of dry tolerance test were as follows: The higher the temperature, the shorter the timeof naiad exposure to the air;3). The results of effects of different sediment on growthof H.tuba were as follows: Growth and survival rate of the cultivation condition withfine sand sediment were better than that without sediment. Then, the cultivationcondition with fine sand sediment is more suitable for naiad H.tuba’s cultivation;4).The results of naiad H. tuba cultivated in sea were as fellows: In breeding period, thegrowth in shell height is0.236mm·d-1, growth in shell width is0.124mm·d-1, increasethe amount of individual weight is0.033g·d-1. The weight growth rate was higher thanthe growth of naiad H. tuba that cultivated in sea.3. Study on digestive system and net cage-cultural of H.tuba: Digestive systemof H. tuba was studied by anatomical and histological techniques. And combined withthe net cage-cultural of juvenile H.tuba, we can have a deeper understanding of itsfeeding mechanism, digest mechanism and feeding habits.The digestive tract of H.tuba consists of the mouth, larynx, craw, esophagus,stomach, intestine, rectum and anus. There is a magnanimous craw in the head ofesophagus. The lumen of after esophagus is diminution. The alimentary turns at thestomach and goes along. Stomach is completely wrapped in the liver. The intestine isfine and straight. The muscular folding proboscis which turns inside lies in the aheadof larynx. The radula wraps in the surface of radula cartilage and can extend intoproboscis cavity to cut and scrape food. The tooth formula is1·1·1. Meanwhile,H.tuba cultured in sea net cage were studied during August2010to August2011. Theresults revealed that there was a faster growth speed of H.tuba cultured in sea net cage.After one year cage culture, Shell high increased by78.6%, shell width increased by92.8%, body weight increased by1029.4%. The average DHG, DW′G and DWGrespectively was0.1mm·d-1,0.06mm·d-1and0.12g·d-1. In Yangjiang city, Yunbo bay,there was a rapidly growth period during April to November, the growth rate at aslower speed during December to March. There present a growth stagnant or evennegative growth phenomenon in January. Under natural sea area conditions, seasonaltemperature changes have a greatest impact on growth of H.tuba, The salinity changethat caused by short-term rains have a small impact on growth of H.tuba. The powerfunction model is fitted on the basis of body weight and shell height of H.tuba, that is,W=0.000003H3.7306, R2=0.943. The liner model is fitted on the basis of shell heightand monthly age of H. tuba, that is, H=2.8454M+36.505, R2=0.9846. The powerfunction model is fitted on the basis of body weight and monthly age of H. tuba, thatis, W=0.6367M1.5322，R2=0.9475. The survival rate was96%. The growth results in different net cage show that: In the same culture conditions, H. tuba cultured in thecage with adherence have rapidly growth rate than the cage that have no adherence.4. Cage-cultured in sea: The stocking density and hanging culture of juvenile H.tuba was respectively studied in Yunbo bay, Yangjiang city. The results of stockingdensity test showed that juvenile H. tuba reared for60days in natural conditions. Theshell height and body weight growth of juvenile H. tuba were exponential type growthunder different stocking density. Except D1group, the SV of other groups weresignificantly reduced. There were significant differences between some growthparameters under the low and high densities treatment after60days. The growth rate,DWG, and SGR of juvenile H. tuba were decreased with the increase of stockingdensities. There was a significantly three times regression relation between SGR anddensity. The correlation equation was SGR=0.8573＋0.1532Dï¼0.0051D2＋0.00005D3（R2=0.9991）. Juvenile H. tuba in group D2, D3have a fast growth rate inall groups. The best stocking density is30individual per net cage. Select the stockingdensities of30individual juvenile H. tuba to culture in Yunbo bay. After100dayshanging cultivation, shell height increased by34.7%, body weight increased by157.4%. The DHG and DWG respectively was0.18mm·d-1and0.173g·d-1. Thesurvival rate is98%. The way of net cage-cultured was suitable for juvenile H. tubabreeding. |
