AP BIOLOGY

Detailed explanation-1: -earthworm, also called angleworm, any one of more than 1, 800 species of terrestrial worms of the class Oligochaeta (phylum Annelida)-in particular, members of the genus Lumbricus.

Detailed explanation-2: -Phylum Annelida is a very broad phylum belonging to the kingdom Animalia. The Annelids are found in aquatic as well as terrestrial environments. These are bilaterally symmetrical invertebrate organisms. Their segmented body distinguishes them from any other organism.

Detailed explanation-3: -Earthworms belong to a class of terrestrial annelids. Hence, earthworms share the characteristics of a typical annelid such as rounded body with segments, presence of a body cavity, complete digestive system, closed circulatory system, and hermaphroditic reproduction.

Detailed explanation-4: -Critical appraisal. 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.