Annelid, phylum name Annelida, also called segmented worm, any member of a phylum of invertebrate animals that are characterized by the possession of a body cavity (or coelom), movable bristles (or setae), and a body divided into segments by transverse rings, or annulations, from which they take their name.

Do annelids have segmented worms?

Annelidasegmented worms(Also: ringed worms) The annelids include earthworms, polychaete worms, and leeches. All members of the group are to some extent segmented, in other words, made up of segments that are formed by subdivisions that partially transect the body cavity. Segmentation is also called metamerism.

Why are annelids called segmented worms?

Annelids are often called “segmented worms” because they possess true segmentation of their bodies, with both internal and external morphological features repeated in each body segment. ... Annelids possess a closed circulatory system, lack a well-developed respiratory system, but have well-developed nervous systems.