Studies On The Reproductive Biology Of Neverita Didyma

The embryonic development of the sea slug Neverita didyma was observed and described at different temperature, brackish water salinity and PH groups and the main factors affecting the veliger larva released were also examined in artificial conditions . In order to provide experimental basis for mantle from Neveria didyma were cultured in the research.The main results showed:1:The gonad development of the Neverita didyma from Yantai sea area was observed by using the tissue slice and H.E. coloration technique. According to the histological character, the gonad development of Neverita didyma may be divided into the following five stages: proliferating stage, growing stage, maturing stage, spawning stage and recovering stage. The reproductive cycle of Neverita didyma is once a year in the Yantai sea area. The spawning season starts from the early of May to the middle of August, their spawning peak is from the early of June to the end of July. The research results proved the laws of gonad development, supplemented data of reproductive biology of Neverita didyma, and had active significance for exploitation and utilization of Neverita didyma.2:The reproductive habit and reproductive capacity were studied in this paper. Its reproductive period is from early apirl . The upper opening mean diameter is 3.68cm, the end opening mean diameter is 3.51cm, high is 2.32cm, the average egg block weight is 8.34g,The individual reproductive capacity is 84174-391245 on average.3:Egg masses of Neverita didyma are artificially hatched at water temperature 25～26~℃and brackish water salinity 32. Based on the morphological change , early development can be divided into 2 stages : embryonic development (including cleavage , blastula and gastrula , egg-trochophora and egg-veliger) and larval development (including Incubationstage , big veliger and creeping larvae).4:Experiments were carried out in a marine culture field of Shan dong Province from Apr.2006 to Apr.2007. Under the conditions of controlled seawater temperature, salinity ,fodder and pH, the influences of temperature and salinity on the growth and survival of Neverita didyma Larvae were studied respectively. The results showed that the suitable temperature was 19～26~℃for larvae, suitable salinity was 29～35 for larvae .The growth was the best and the survival rate was the highest at sea water pH value from 7.5 to 8.5,"Chlorella saccharophila"and"Chaetoceros muelleri Lemmermann"is fit for fodder of the larvae of Neverita didyma Larvae...