Segmented worms are placed in the phylum Annelida, which consists of over 12,000 species of segmented worms grouped into three classes comprising freshwater worms and earthworms, marine worms, and leeches.

One of our Canadian readers’ two-year-old son and her husband had just finished up a shower when they found this…

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.

A reader recently wrote to us inquiring about the evolution of worms. He asked several specific questions about the evolutionary history of worms, not all of which we can answer, but we can sketch a picture, even if incompletely, of the evolution of worms.

Common species include Aphrodita hastate and A. aculeate. Aphrodita hastate occurs on the North American coast from the Gulf of St. Lawrence to Chesapeake Bay and A. aculeate is a common European species.

Marine worms come in a variety of shapes and sizes. They may be long and thin, plumb and short, flattened and floppy, bright and colorful or dull and dark.