A COMPLETE LIFE-CYCLE OF THE CALYCOPHORAN SIPHONOPHORE MUGGIAEA-KOCHI (WILL) IN THE LABORATORY, UNDER DIFFERENT TEMPERATURE CONDITIONS - ECOLOGICAL IMPLICATIONS

For the first time, a complete life cycle of a siphonophore has been achieved in culture at different temperatures, in the small species Muggiaea kochi. The larval, polygastric and eudoxid stages are described, and their duration and rate of production determined. The results show that the cycle from egg to egg lasts two weeks at 24-degrees-C and three weeks at 18-degrees-C. Furthermore, two types of life cycle have been observed: a short cycle at 18-degrees-C and 24-degrees-C characterized by a short (2-3 weeks) polygastric phase, and a long cycle at 13-degrees-C marked by the persistence of a stationary polygastric phase. The experimental results are discussed in relation to the seasonal distribution of the species in the Bay of Villefranche-sur-mer.