Copepod bodies are divided into two regions, the forward region is the prosome and the back region the urosome. These regions are separated by the major articulation or flexing point in the body. Different copepod groups have different numbers of segments in the prosome, so no generalization can be made.
Calanoid copepods have enlarge first antennae which they often use for swimming. Calanoids can also be distinguished by a broad prosomes and narrow urosome whereas harpactacoids prosome and urosome are similar widths. In both groups all appendages are found on the prosomal segments except for the spiney appendages on the last body segment called the caudal ramus.