For a parasitic organism such as ascaris what would be the selective advantage of a cuticle

Ascaris is a type of parasitic nematode worm that inhabits the small intestine of its host, which includes humans. The intestine can be a harsh environment for biological material as it is alkaline and contains enzymes to facilitate the break down and absorption of nutrients. The presence of a cuticle can act as a physical barrier, protecting the parasite from these elements. 

Active site is where they touch.