On the premise that the effects of body mass. habitat temperature and habitat depth on the metabolism are common across pelagic animal taxa, the respiration rates of fishes and cephalopods were compared with the rates of pelagic crustaceans. which include copepods (109 species), euphausiids (24 ), amphipods (32). mysids (32) and decapods (43) [selected from metazooplankton datasets in the Supporting mate-rials in Ikeda (2014), with fishes (fish) and cephalopods (Ceph) being designated as the dummy variables: