Including the families Enchytraeidae and Propappidae, possibly also some small, less known marine families. Number of species larger than 700. Two families known from fresh waters of NWE: family Enchytraeidae and family Propappidae, with 8 genera and 24 species. Considerably more taxa are living in soil and in the marine littoral of the same region.
Description
Mostly small or medium-sized oligochaetes, of white, yellowish or reddish colour. Chaetae simple-pointed or bifid but never hair-shaped, in various numbers per bundle. Male ducts plesioporous, with testes and male funnels usually in XI, vasa deferentia and male pores in XII; atria usually not developed but penial bulbs with several additional glands often present at male pores. Ovaries in XII. In asexually reproducing forms, all this set can shift forward by several segments. Spermathecae always in V (but ampullae can reach backward by several segments), with ectal pores dorsally or laterally in 4/5 or IV; often communicating with oesophagus by ental duct. The position of spermathecae in V (or IV), with all the remaining reproductive organs lying several segments rearward, is most characteristic of the order.
Burrowing in sediment.
Distribution
Cosmopolitan.
Ecology
In soil, in marine littoral and marine, brackish and freshwater.
Reproduction
Mostly sexual only, with eggs laid in cocoons; asexual reproduction by architomy (fragmentation) in some forms.
Literature
Henle, 1837: 74-90; Vejdovsky, 1879: 50; Vejdovsky, 1884b: 40-42; Michaelsen, 1930: 416-418; Nielsen and Christensen, 1959: 26-29; Brinkhurst and Jamieson, 1971: 654; Chekanovskaya, 1981: 365-370; Kasprzak, 1986: 11-41, 68-78; Coates, 1986: 418-419.