Morphological differences between free-living soil and freshwater nematodes in relation to their environments

Abstract

Summary There is no single feature to distinguish free-living soil nematodes from freshwater nematodes, also because all free-living nematodes are essentially aquatic. This notwithstanding, by examining the frequencies of some characters of 1141 European species, differences of qualitative/quantitative characters between soil and freshwater nematodes were found. In particular, aquatic and semi-aquatic species are, on average, longer and slimmer than soil species, have a longer tail, greater body weight, smooth cuticle and larger amphids. A new body parameter, length of the pharynx in relation to the length of the whole digestive tract (e), was also taken into consideration.