Calanus euxinus

Calanus euxinus is a copepod ubiquitous to the Black Sea and the Marmara Sea and a main source of prey for small and juvenile fish as the largest part of the zooplankton biomass.

Calanus euxinus was misidentified originally as a variation of Calanus finmarchicus and Calanus helgolandicus, until being labeled as its own species. Calanus euxinus are considerably larger than Mediterranean species, like Calanus helgolandicus, with a larger lipid reserve.

Previous origin hypotheses, assumed the Black Sea Calanus to be derived from a population of Calanus helgolandicus in the Mediterranean, but more recent phenetic research points to earlier population divergences from the Boreal derived Calanus.