Figure 23.5: Body Segmentation (A) All of the segments of this marine clam worm, an annelid, are similar. Its appendages are tipped with bristles (setae) that are used for locomotion. (B) Segmentation allows the evolution of differentiation among the segments. The segments of this scorpion, an arthropod, differ in their form, function, and the appendages they bear. (C) Muscular segmentation is clearly visible in the abdomen of this body builder.