Calanus agulhensis is the dominant large copepod on South Africa's Agulhas Bank, and is an important food item for pelagic fish. This paper reviews current knowledge and understanding of its biology and ecology and includes comparisons with other Calanus species. Its distribution is influenced by the prevailing hydrography, being advected from the eastern to the western Agulhas Bank and then north along the edge of the west coast shelf. Highest biomass of C. agulhensis is on the central Agulhas Bank in the vicinity of a cool ridge of upwelled water that is thought to enhance local retention. Daily vertical migration on the Agulhas Bank is linked to food concentration, with a strong correlation between the extent of migration of large stages (C4-female) and food abundance in the chlorophyll-rich layer. A diel feeding rhythm has been observed, independent of whether or not animals are migrating vertically. Females offered natural assemblages show a preference for the larger particles of the dominant size classes. Development time from egg to adult (20.3 d at 15.5°C) is fast compared with other Calanus species. The long N3 stage duration suggests that it is the first feeding stage. Isochronal growth is approximated, but the equiproportional rule is not adhered to. In the field, growth rate is influenced more by food than by temperature, particularly larger stages that are more frequently food-limited. This is probably because the small phytoplankton cells that dominate at warm temperatures are generally at low concentrations (<2 mg chlorophyll a m–3), insufficient for fast growth of large stages. Egg production following short periods (1–3 d) of starvation returns quickly to normal on the reintroduction of food, an adaptation that may be beneficial in the relatively stable food environment of the Agulhas Bank. Following long periods (9 d) without food, however, many females are unable to regain normal levels of egg production. At present, there is no information on the extent of omnivory in C. agulhensis, and little on the ecology of the naupliar and young copepodite stages. These may be fruitful areas for future research.