(Schmidt, 1847)
Description
Small transparent worms. Prostomium with distinct thin proboscis. Eyes present. Dorsal bundles beginning from VI. In VI-VIII, they consist of 2-16 extremely long (780-1700 µm) hair chaetae accompanied with 2-6 shorter (280-400 µm) hair chaetae and 10-18 fine single-pointed needle chaetae (66-96 µm). Beginning from IX, 1-3 hair chaetae (165-180 µm) and 1-3 needle chaetae (60 µm) per bundle. In ventral bundles of II-III, 2-7 chaetae with longer upper tooth, 93-99 µm long in II, 66-72 µm long in III. In IV and V, ventral chaetae are lacking; from VI on, ventral chaetae by 3-8, with shorter upper tooth. In mature individuals hooked penial chaetae by 2. Length 2-7.5 mm, segment number in zooids 14-21, in single individuals 23-39. Easy to recognize by its unique long hair chaetae.
Crawling on substratum, swimming.
Distribution
Holarctic, also in Japan.
Ecology
In freshwater. Constructing mucous tubes. Sometimes floating in plankton. Using long hair chaetae for filtering fine food particles from water.
Reproduction
Mostly asexual, by paratomy (budding). Mature individuals and sexual reproduction rare or seasonal.
Literature
Schmidt, 1847: 320; Bourne, 1891: 349; Sperber, 1948: 143-147, Figs 15H-K, 16, 26C, Pl. IX Figs 4-7; Sperber, 1950: 68, Fig. 17H-K; Brinkhurst and Jamieson, 1971: 351-352, Fig. 7.10L-N; Chekanovskaya, 1981: 202-203, Figs 83-84; Hrabe, 1981: 53, Pl. 8 Fig. 16; Kasprzak, 1981: 109, Figs 261-265.