Study On The Life History Of Mycale (Mycale) Phyllophila Hentschel,1911

Mycale (Mycale) phyllophila Hentschel,1911(Demospongiae, Poecilosclerida, Mycalidae) is one of the most widespread littoral sponge in Dongshan Bay and Fotan Bay in Fujian Province. Some preliminary research on bioactive compounds in our research group suggested that M. phyllophila could be a significant source for pharmaceutical industry, due to the richness of alkaloid and sterols, as well as the highly activities of nuclear receptor. Our research group decided to carry on the study of basic biology along with lead compound research in case of the natural sponge resources destruction in the process of exploitation. The creative study process made it possible to observe the living habit which could be the foundation of large-scale cultivation. Thus, biological researches on M. phyllophila are valuable and necessary. The present study focused on the embryonic development, larvae release characteristics, larval settlement and metamorphosis, growth of juveniles and adult asexual reproduction of M. phyllophila.The results suggested that, M. phyllophila was a hermaphroditic species, and oogenesis and spermatogenesis were asynchronous. The primary oocytes measured30-50μm in diameter, while the mature ones could reach the size of300-400μm by engulfing the nurse cells around them. Spermatogonia were14-16μm big and gathered together inspermatic cysts at the size of97.15±12.11μm. The sizes of sperms ranged from3to5μm with oval grainy shape. The zygotes were spherical, milky white and measured about400-500μm in diameter and incubated in the brood chambers which usually situated at the base of the big osculum. Divisions during the embryonic development were unequal. The larvae were matured in the brooding adult before they released from the osculum. The reproduction cycles of M. phyllophila were affected by water temperature to a large extent, and the reproduction periods always started in the season at a relatively higher water temperature. In this research, we found that oogenesis and embryogenesis lasted from mid-June to November, and spermatogenesis started in the end of May and lasted to the earlyNovember while the larvae release happened from early July to the end of October. Even though we could see the embryos in the sponges in November, no larvae were observed at all. The larvae release of M. phyllophila was found mainly from July to October during the year, while the larvae releasd most at04:30-08:00of the day. The amounts of larvae release were different among individuals. The largest release amount was1.24X104observed within one individual a day M. phyllophila juveniles developed an obvious osculum in seven days after attachment. The survival rates of juveniles were above65%after40days’culture in lab. The sizes of juveniles changed from500μm to3mm. The juveniles which were cultured in lab were transplanted at sea after40days. After being cultured at sea for60days, the mortality of juveniles was very high, and the largest survival rate of juveniles was only27.78%in a single petri dish. Fortunately, the survived individuals all grew well and reached10cm in diameter after200days’growth.The examination on the effects of L-3,4-dihydroxyphenylalanine (L-DOPA), epinephrine and dopamine on larval settlement and metamorphosis of M. phyllophila suggested that all the compounds were not appropriate inducers for larval settlement and metamorphosis in M. phyllophila because they were more or less toxic to the sponge larvae. We researched the effects of some specific physical factors on larval settlement of M. phyllophila, including light (illumination) intensity, substrate types and salinity. The results demonstrated that the larvae were photophobic to light and preferred to settle in the dark. Compared to the smooth sheets, larvae preferred to settle on the relatively rough ropes. The appropriate concentration of salinity was35.It may be an effective way to increasing proliferation of M. phyllophila issues by culturing at sea (with ropes)., for the recent experiment provided a good example of culturing sponge tissues for3months at the survival rate of100%.The tissues grew laterally in the early stage while changed to longitudinally in later period. But some tissues partially died because of enemies as well as water quality and totally died after the temperature dropped. As a result, we hold the point of view that the asexual reproduction of Mycale phyllophila is greatly influenced by temperature.