Cultivation experiments on North Sea ctenophores
- W. Greve1
© Biologischen Anstalt Helgoland 1970
1. The development of new cultivation devices, the double kuvette and the phytoplanktonkreisel, made it possible to culture the 4 species of ctenophores occurring in the southern North Sea:Pleurobrachia pileus, Bolinopsis infundibulum, Beroe cucumis andBeroe gracilis. These ctenophores are holoplanktonic organisms of great ecological importance in local marine food chains.
2. The double kuvette, an improved version of the planktonkreisel permits the control of growth and feeding rate without disturbing the test organisms.
3. The phytoplanktonkreisel permits experiments close to habitat conditions with high seston densities and wave action.
4.Beroe gracilis andPleurobrachia pileus could be reared from egg to egg; the other 2 species could be maintained over several weeks.
5. Data are given on the nutrition of all 4 species as well as on their growth rates, development and behavior.
6.Beroe gracilis feed exclusively onPleurobrachia pileus; Beroe cucumis feed mainly onBolinopsis infundibulum.
7. The young stages only ofBolinopsis infundibulum have true larval organs (tentacles) and may be called larvae.
8. Some ecological implications of the findings are discussed.