Two techniques are described to calculate energy densities for the bell, gonad and oral arm tissues of three scyphozoan jellyfish
(Cyanea capillata, Rhizostoma octopus and Chrysaora hysoscella). First, bomb-calorimetry was used, a technique that is readily
available and inexpensive. However, the reliability of this technique for gelatinous material is contentious. Second, further analysis
involving the more labour intensive proximate-composition analysis (protein, fat and carbohydrate) was carried out on two species
(C. capillata and R. octopus). These proximate data were subsequently converted to energy densities. The two techniques (bombcalorimetry
and proximate-composition) gave very similar estimates of energy density. Differences in energy density were found
both amongst different species and between different tissues of the same species. Mean (±S.D.) energy density estimates for whole
animals from bomb-calorimetry were 0.18 ± 0.05, 0.11 ± 0.04, and 0.10 ± 0.03 kJ g wet mass−1 for C. capillata, R. octopus, and
C. hysoscella respectively. The implications of these low energy densities for species feeding on jellyfish are discussed.
© 2007 Elsevier B.V. All rights reserved.