A class of worms that have very well-developed metameric segmentation. The segments have only a few chaetae (hence the name), but parapodia are not present. They are all hermaphrodites; asexual reproduction is predominant in aquatic forms. Eyes and tentacles are absent. A few marine forms occur but most are freshwater or terrestrial. There are 15 families, and the class is first recorded from the Late Ordovician.
Subjects: Zoology and Animal Sciences — Earth Sciences and Geography.