Co-occurrence of hippopodiid siphonophores and their potential prey

It is a truism that the distribution of a predator should reflect that of its potential prey, but this is not well established for marine plankton communities. Purcell (1981) found that many siphonophore species were selective feeders and that one, Hippopodius hippopus, fed exclusively on ostracods. Pugh (1986) speculated that if such a dietary specificity also applied to other hippopodiid species, then a distributional relation between them and ostracods might be expected. This premise is examined using data from Discovery stations in the N.E. Atlantic Ocean. A clear relation is found between the abundance of ostracods and hippopodiids, while copepods have a better relation with other calycophoran siphonophores.