Vejdovsky, 1884a
Description
Stout, transparent worm, usually occurring as a chain of several zooids. Five anterior segments fused forming head and containing muscular pharynx. Prostomium absent. Chaetae in ventral bundles only, absent from III-V. Those of II 4-13 per bundle, 108-165 µm long and less than 2 µm thick, 4-13 per bundle; from VI on 4-6 per bundle, 81-130 µm long. Upper tooth of chaetae slightly longer. In mature individuals, clitellum in 1/2 V-VI, and penial chaetae in VI 2 per bundle, 53-69 µm long, blunt. Length 2.5-7 mm, segment number in the first zooid 8-9. Intermediate in size between Chaetogaster diaphanus and other, smaller species. Can be (and probably was) confused with young individuals of the latter. Blood vessels on the stomach wall can serve as a distinguishing character: In Chaetogaster diaphanus, stomach in V-VII is surrounded by a blood plexus but with several transversal blood vessels in its anterior part, while in Chaetogaster cristallinus the stomach is surrounded by about 20 pairs of distinct transversal blood vessels not forming any plexus (visible in live worms). The notch on the upper edge of the mouth, erroneously attributed to this species by Sperber, 1948, 1950, is rather characteristic of Chaetogaster diaphanus, according to Poddubnaja, 1966.
Crawling on substratum.
Distribution
Almost cosmopolitan.
Ecology
In various freshwater bodies, seldom in slightly brackish water, living on water plants and bottom sediment. Feeding on small invertebrates as cladocerans, chironomid larvae, oligochaetes etc.; ingested prey in stomach well visible through transparent body wall.
Reproduction
Paratomy (budding). Sexually mature individuals rare.
Literature
Vejdovsky, 1884a: 220; Sperber, 1948: 68-71, Figs 7E, K, Pl. II Figs 1-3; Sperber, 1950: 53, Fig. 3E; Poddubnaja, 1966: 120-121; Brinkhurst and Jamieson, 1971: 311-312, Fig. 7.1L-N; Chekanovskaya, 1981: 259-260, Figs 120-121; Hrabe, 1981: 33, Pl. 2 Figs 5-8, 12.