Chaetonotida

Article By:

Hummon, William D. Department of Zoological and Biomedical Sciences, Ohio University, Athens, Ohio.

Last reviewed:October 2019

DOI:https://doi.org/10.1036/1097-8542.123300

An order of the phylum Gastrotricha. Members have Y-shaped pharyngeal lumina. Neodasys is a marine and macrodasyid-like form that reaches 0.8 mm (0.03 in.) in length and has front, side, and rear adhesive tubes. Others seldom exceed 0.3 mm (0.01 in.); they have only two rear adhesive tubes borne on a posterior furca, or none at all. Members of the family Xenotrichulidae have locomotor cilia grouped into cirri; all three genera are marine (illus.a). The family Chaetonotidae comprises half of all gastrotrichs: Musellifer and Halichaetonotus are marine; Polymerurus is freshwater; Aspidiophorus, Chaetonotus (illus.b), Heterolepidoderma, Ichthydium, and Lepidodermella have species in each habitat. Musellifer lives in mud; all others inhabit sands of streams, beaches, or offshore banks, or live in the surface detritus of ponds or lake bottoms. The other seven genera, in four families, are all freshwater and either are rare or tend toward a semiplanktonic life, especially Neogossea and Stylochaeta. Several chaetonotids are easily kept in aquatic microcosms, and a few, such as L. squamata, are readily cultured in pond water on wheat grains. See also: Gastrotricha

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