(Müller, 1774)
Description
Transparent worms with posterior branchial disc. The latter bearing, besides 3-4 pairs of gills, also one pair of finger-like non-contractile palps well visible even in killed worms. No eyes. Dorsal chaetal bundles beginning from V, consisting of one hair chaeta, 85-200 µm long, and one bifid needle chaeta, 45-62 µm long, with shorter upper tooth. Ventral chaetae by 2-5, 54-73 µm long, in anterior bundles upper tooth slightly longer, in posterior bundles, shorter. Length 6-20 mm, segment number in zooids 11-25, in single individuals 35-82.
Crawling on substratum. Able to swim.
Distribution
Cosmopolitan.
Ecology
In freshwater, preferring warmer habitats. Tolerant of oxygen deficiency and pollution. Feeding on detritus. Builds attached or portable cases.
Reproduction
Mostly asexual, by paratomy (budding). Mature individuals and sexual reproduction rare.
Literature
Müller, 1774: 23; Sperber, 1948: 191-194, Fig. 20B-D; Sperber, 1950: 72-73, Fig. 25; Brinkhurst and Jamieson, 1971: 376-377, Fig. 7.17A-D; Chekanovskaya, 1981: 217-218, Fig. 93; Hrabe, 1981: 58-59, Pl. 9 Figs 9-13; Kasprzak, 1981: 110, Figs 266-271.