In the laboratory, a Folsom splitter was used to split the zooplankton samples in to subsamples until each subsample contained approximately 300 specimens. Jellyfish were categorized and identified at the species level according to the keys proposed. The number of jellyfish belonging to each taxon was recorded as in dividuals / m3 (ind/m3). A jellyfish (siphonophores) was included in the sample when ever its nectocalyx (anteriornectophore) was present. Jellyfish that were broken to pieces were ignored during the identification process.