Nematodes are presumably the most numerous Metazoans in terrestrial habitats. They are represented at all trophic levels and are known to respond to nutrient limitation, prey availability, and microbial resources. Predatory nematodes reside at the highest trophic level, and as such their feeding habits could have a major impact on soil food web functioning. Here, we investigate the effects of gender and developmental stage on the nematode body sizes in coarse and loamy soils. Besides Neodiplogasteridae, our predators are much larger than other soil-dwelling nematodes from their early developmental stage onwards. From juvenile to adult, the predatory Aporcelaimellus (Kruskal–Wallis P < 0.001), Dorylaimoides, and Tripyla (both P < 0.01) show great length increases during their developmental growth, in contrast to their possible prey (almost all P < 0.001). Less than 4% of the prey exceeds the length of the predatory adults, but more than 30% of the prey exceeds the length of the predatory juveniles. Potential body size ratios and some physical problems experienced by small fluid feeders attacking large prey are discussed in an attempt to summarize different prey-searching mechanisms and aggregative predatory responses in the soil system.
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机译：线虫大概是陆地生境中数量最多的后生动物。它们代表了所有营养级别，并且已知对营养限制，猎物可利用性和微生物资源有反应。捕食性线虫处于最高营养水平，因此它们的摄食习惯可能对土壤食物网的功能产生重大影响。在这里，我们调查了性别和发育阶段对线虫体大小在粗壤和壤土中的影响。除新线虫科外，从其早期发育阶段开始，我们的食肉动物就比其他居住在土壤中的线虫大得多。从幼年到成年，掠食性Aporcelaimellus（Kruskal–Wallis P <0.001），Dorylaimoides和Tripyla（P <0.01）与它们的猎物相比，在生长发育过程中长度显着增加（几乎所有P <0.001）。少于4％的猎物超过了捕食者的体长，但超过30％的猎物超过了捕食者的体长。讨论了潜在的体型比率和小型流体饲养者攻击大型猎物所遇到的一些物理问题，以试图总结土壤系统中不同的猎物搜索机制和综合掠食性反应。
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