[1] They are a dominant component of the open water ecosystems of the northern Pacific Ocean.

[2] Neocalanus are large copepods, reaching body lengths (i.e., prosome length) of more than 8 mm (0.31 in) in Neocalanus plumchrus.

[3] There are six species:[1] Neocalanus flemingeri is predominantly annual, with a significant fraction of biennials in some areas.

The largest females reach prosome length of about 5 mm (0.20 in); males are smaller.

[4] Neocalanus are important food items for many predators, such as North Pacific right whale[5] and least auklet.