1. Origin of appendages

2. Annelids (Polychaetes)
Metamerism
Segmentally arranged parapodia
Longitudinal muscles contracting in an asymetrical pattern.

3. Oligochaetes Every segment works independent of the other.
Symmetrical wave passes down the length of the organism causing each segment to either be long and slender or short and fat. If short and fat, then bristles come in contact with burrow wall and force is applied.

4. Control
Whether polychaete or oligochaete, each segment has a pair of ganglia.
Supraesophageal ganglia are associated with sensory function, whereas subesophageal ganglia are associated with motor function.