How the structure of the body wall places limitations on shape changes in nematodes?

The body wall of nematodes is composed of a tough cuticle, a layer of muscle, and a hypodermis, which collectively provide structural support and protection. This rigid body wall limits the degree of shape change because it resists deformation, constraining the body to a cylindrical form. As a result, nematodes primarily rely on longitudinal muscle contraction for movement, which allows for bending and thrusting, but restricts more complex shape alterations. Consequently, their movement is largely linear and undulatory, reflecting these anatomical constraints.