INVERTEBRATE ZOOLOGY IN THREE BOOKS - BOOK 1 - H.Y. Shcherbak - 1995

SUBKINGDOM MULTICELLULAR ANIMALS (METAZOA)

SECTION EUMETAZOA

PHYLUM NEMATHELMINTHES

CLASS NEMATODA (NEMATODES)

Subclass Chromadoria

Most chromadorians are free-living marine forms, less commonly found in freshwaters and soils, and rarely as invertebrates commensals.

These are very small nematodes with long body bristles bearing small papillae-like receptors. The stoma contains Teeth and onchia. The cuticle of chromadorians is annulated, with the rings often encrusted with thickenings of various shapes. These nematodes feed on unicellular Algae or small animals. Some of them—the plectids (order Plectida)—have adapted to life in freshwater bodies and soil, where they feed on decomposing organic matter, ingesting liquid decay products along with Bacteria. The most widespread orders are Chromadorida and Plectida, which comprise free-living marine, and less frequently freshwater and soil-dwelling forms (Fig. 203).

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Fig. 203. Order Chromadorida (Chromadorina longisetosa) — anterior (a) and posterior (b) ends of the body:

1 — sensory setae; 2 — labial papillae; 3 — onchia:



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