GENERAL HISTOLOGY

Detailed explanation-1: -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.

Detailed explanation-2: -Most authors accept the annelids as having three major classes: Polychaeta, Oligochaeta, and Hirudinea. Older systems would place the polychaetes and oligochaetes under the class Chaetopoda because both groups possess setae.

Detailed explanation-3: -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.

Detailed explanation-4: -Burrowing annelids, like the earthworm, play an important role in helping organic matter decompose. Earthworms eat dead plants and animals. When they eat, they also take in soil and tiny pebbles. Earthworms take in nutrients from microorganisms in the material they ingest.