Final answer:
Nematodes possess unique body-wall muscles that attach directly to their nerve cords, resulting in a distinctive whiplike movement, and their cuticle and hydrostatic skeleton system facilitate efficient movement.
Step-by-step explanation:
Two peculiar features of the body-wall muscles in nematodes include their unique attachment and the nature of their muscles.
Firstly, nematode muscles are attached directly to the dorsal and ventral nerve cords. This attachment is distinctive from most animals and results in the characteristic whiplike body movement of nematodes, which is due to the presence of a single layer of longitudinal muscles. Unlike other animals, nematodes do not possess circular muscles, allowing them only side-to-side, wave-like undulation.
Secondly, the body-wall muscles of nematodes facilitate movement in conjunction with their hydrostatic skeleton. This is created by the cuticle that encases the nematode's body, which is rich in collagen and chitin. The cuticle is non-expandable, thus enabling the buildup of fluid pressure in the pseudocoelom, providing a counterforce for muscle contractions; an efficient system for locomotion along solid surfaces.