Haunost, Mathias (2012) Growth of scyphozoan polyps under different feeding conditions. (Diploma thesis), Christian-Albrechts-Universität Kiel, Kiel, Germany, 88 pp.

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Abstract

Scyphozoa play an important role in marine ecosystems. In recent years, rising numbers of jellyfish have been observed worldwide, with potentially dramatic effects for the food web. Jellyfish have a complex life cycle which includes a changing of generations. The medusae stages are much larger and more visible and have therefore been more intensely studied than the polyp generation, which is smaller, benthic and sessile. Polyps, however, are a crucial life stage in the recruitment of Scyphomedusae and therefore require more investigations in order to assess their importance in marine ecosystems. This study contributes to the understanding of the ecology and food spectrum of the polyps. To date very little is known about the feeding of polyps, in particular with regard to the food size. As food is a determining factor in the survival and development of polyps, this study investigates the size class of food best suited for two different polyp sizes. The polyps were fed with Artemia of four different and distinct size classes and their growth determined with different measurements. The results of this study indicate that larger polyps are capable of feeding on a wider range of prey sizes than the small polyps. Prey organisms of an optimal size have to be smaller than the polyp feeding on it in order to enable direct and complete ingestion of the prey item.

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