What happens if the Nematode epidermis becomes damaged?
Nematodes have external skeleton in the form of a cuticle. Their muscles are attached to this external skeleton and when a muscle cell contracts it moves a segment of the cuticle relatively to the other segments, which in turn allows the pushing of the environment and thus, motility. This is very similar to how we, humans, move.

Damaging the cuticle in nematodes results in motility impairment. For example, some C. elegans strains have a mutation that results in a non-normal cuticle formation which makes the animals roll instead of moving peristaltically (like a snake).

In addition, some muscles are not skeletal muscles, or body wall muscles in the case of nematodes. These muscles affect movement of an organ like the pharynx in nematodes or the heart in humans.

for further reading regarding the body wall muscles and cuticle interaction you can see wormatlas.org

References:


Labouesse, M. 2006. Epithelial junctions and attachments. WormBook, ed. The C. elegans Research Community, WormBook, doi/10.1895/wormbook.1.56.1