Segmented Worms, typeAnnelida;

Animals belonging to this phylum are characterized by metamery, which means that they have body built from similar segments. The general layout of the body can be described as an elongated sac or a tube with the mouth opening at one end and the anal opening at the other. These openings are connected by a simple digestive system.

Locomotion organs of a segmented worm consist of bristle clusters or pairs of parapodia (Parapodia are fleshy lateral outgrowths equipped with bristles (setae). They are the locomotion organs of polychatetes).

Segmented worms reproduce sexually. They may have separate sexes or be hermaphroditic. Polychaetes are most often found in marine environment, e.g. sabellids (Sabellidae) and Christmas trees or serpules (Serpullidae). The main difference between Serpullidae and Sabellidae is that the former produce a hard calcareous tube – an external skeleton.