Annelida is a phylum of segmented worms, including earthworms, leeches, and ragworms. They have a cylindrical body divided into segments, each with its own set of organs. They have a well-developed nervous system and a closed circulatory system. Annelida can be found in a variety of habitats, from freshwater to marine environments, and from the tropics to the poles. Their lifespan varies from a few months to several years, depending on the species. The current population of Annelida is estimated to be around 15,000 species.
Name Origin: Annelida is a phylum of segmented worms, and its name is derived from the Latin word for "little ring" or "ring-shaped," referring to the body segments of the worms. The name was first used by Aristotle in the 4th century BC, and was later adopted by Carl Linnaeus in the 18th century.
Related Species: Polychaeta, Hirudinea, Oligochaeta, Echiura