Only the vermiform stages of any nematode species have the ability to move through soil, water, or tissue.
Movement is aided by four sets of longitudinal muscles that extend throughout the entire body.
Contractions in pairs of these muscles enable movement in a dorsal-ventral plane. When vermiform nematodes are extracted from soil and placed in a dish of water under the microscope, they are usually lying on their sides. The nematode body is a pressurized system in which the elastic cuticle acts as a hydrostatic skeleton providing a back force following muscular contraction that allows forward movement. Phytonematology Study Guide. University of California, Division of Agriculture and Natural Resources.