| The somites are first formed in the neck, and are added successively behind in the unsegmented posterior region of the embryo. |
| Sipunculans, or peanut worms, have an unsegmented body with a retractable introvert. |
| Moreover, this rod was unsegmented, for the notochord is devoid of segmentation. |
| The fin rays sprouting from the ends are also unique in having a long, stiff unsegmented basal area. |
| These unsegmented worms have been found in Cambrian rocks, such as the legendary Burgess Shale. |
| Phylum Nemertea contains about 1,150 species of unsegmented worms that possess an eversible proboscis contained in a fluid-filled cavity or rhynchocoel. |
