The diel vertically migrating copepod, Pleuromamma xiphias, migrates approximately 600 m daily, up and down in the water column. At the surface, the copepods feed on plankton at night, and then descend to the depths during the day, likely to escape visual predators. Both the migratory behavior and the physiological pathways that are up- and down-regulated throughout the migration are likely under at least partial circadian clock control. This experiment compares the protein abundances of select physiological processes from copepods collected in situ with copepods incubated in the dark to remove the influence of exogenous stimuli on physiology.