Biochemical composition of ctenophores

The biochemical composition of three species of North Sea ctenophores, the beroid Beroe gracilis (Künne), the tentaculate Pleurobrachia pileus (Fabricius) and the lobate Bolinopsis infundibulum (Müller), was analysed in terms of total fractions of protein, lipid, ninhydrin-positive substances (NFS), polysaccharides (PS), and low molecular-weight carbohydrates (LMC). The sum of these biochemical fractions was highest in Beroe (128 mg/g dry wt) and much lower in Pleurobrachia (61 mg/g dry wt) and Bolinopsis (27 mg/g dry wt). Beroe shows higher ratios of NPS/protein and LMC/PS than either of the other species. These findings are explained by differences in the morphology and metabolism of the species.In a 3-wk starvation experiment, Pleurobrachia lost ≈65% of its body mass and ≈80% of its organic content after 14 days at 15°C. However, after 10 days, the biochemical composition of the body tissue changed only slightly indicating that all components of body tissue are consumed without any preference for a specific storage material. Therefore the biochemical composition does not necessarily reflect differences in the nutritional conditions of the ctenophores the field.