Acartia omorii is a species of marine copepod belonging to the family Acartiidae.[1] This species was discovered when specimens previously identified as Acartia clausi were examined and found to belong to a separate species.[2] This species is found around the coast of Japan.[2] It is similar to A. clausi but lacks the prominent spines on the dorsal part of the posterior body segment (metasome).[2]