Distribution and life history of two planktonic copepods, Rhincalanus nasutus and Rhincalanus rostrifrons, in the northwestern Pacific Ocean

► We revealed seasonal OVM of two tropical-subtropical Rhincalanus in the NW Pacific. ► Two Rhincalanus species might have 1 or 2 year life cycles. ► C6 female dormancy is an adaptation to the tropical-subtropical oceans. ► Shallower dormancy of R. rostrifrons is more advantageous in these oceans. ► Seasonal OVM is a common life-history strategy among the Eucalanidae family.