Grube, 1850
Number of species about 10,000. In fresh waters of NWE, 24 known species representing two orders, Archiannelida and Aeolosomatida, with three families: Family Nerillidae, Family Aeolosomatidae and Family Potamodrilidae.
Description
The largest but vaguely defined, possibly paraphyletic group of traditional annelids, including most of their numerous clades except the well-defined class of Clitellata. It is difficult to find any synapomorphies for Polychaeta, except for nuchal organs, a pair of lateral sensory organs on head end (Rouse and Fauchald, 1995; Purschke, 1997). Presence of parapodia, paired tentacles and palps on anterior end, ventral pharyngeal pad, as well as lack of clitellum etc. are characteristic of many but not all representatives of this class.
Distribution
Cosmopolitan.
Ecology
Mostly marine, less in freshwater, very seldom in soil.
Reproduction
Both sexual and asexual ways of reproduction can occur in different groups.
Literature
Grube, 1850: 281; Fauchald, 1977: 1-188; Rouse and Fauchald, 1995: 269-301; Fauchald and Rouse, 1997: 71-138; Purschke, 1997: 123-143.