Oncaeidae are small copepods that serve an important role in marine ecosystems, with high abundance and rich diversity. Studies on the taxonomic diversity of these species still have great deficiencies, and its ecological function status may be underestimated.

The diel vertical distributions of two small copepods, Oithona similis and Oncaea curvata, were investigated at 4-h intervals over a 24-h period under fast ice near Syowa Station during continuous daylight conditions in the Antarctic mid-summer, December

During the austral spring period of 1996, the composition, age structure and physiological activity of zooplankton were studied in the Indian sector of the Southern Ocean. Zooplankton biomass ranged from less than 1 g m−2 in the Northern Polar Front Zone