These copepods, which are of small to medium size, exhibit distinct characteristics in their females and males. Females have a rostrum that is divided into two parts, while males possess a reduced and knob-like rostrum. The body segments at both the front and back are rounded in shape. Notably, the head segment, known as the cephalosome, is fused with the first body segment.In females, the fifth leg, referred to as P5, is uniramous, meaning it has a single branch. P5 in females is symmetrical and consists of three segments. On the other hand, in males, the structure of P5 is also uniramous, but the legs are of unequal length. The longer leg is typically found on the left side and is made up of five segments. The fifth segment of this longer leg is short and attaches slightly below the previous segment. In contrast, the shorter leg in males has three segments and is less than half the length of the first segment of the longer leg.The female’s urosome, which is the posterior part of the body, is divided into four segments. It’s worth noting that these copepods can sometimes be confused with Paracalanus females. However, a distinguishing feature is the structure of their P5, which sets them apart from Paracalanus.