The annelids are a large phylum of segmented worms; consequently, annelids are commonly called simply “segmented worms.” (They are also, by the way, called “ringed worms,” as the worms’ segmented bodies often make them look like they are wrapped in small rings.) There are over 17,000 species in the annelid phylum, according to recent research, and while this is far less diverse than the phylum Nematoda, which is estimated to have approximately 1,000,000 species, the annelids are still extremely diverse relative to other species of animals.