Parasitic Helminthes have all of the following characteristics except:

Parasitic helminths, commonly known as worms, exhibit several important characteristics that define their biology and life cycles. One key characteristic is that they are multicellular organisms, which allows them to develop complex structures and specialized systems needed for their parasitic lifestyle, including reproductive systems that enable them to produce numerous offspring. They also exhibit parasitic behavior, relying on a host for survival and reproduction, which is central to their life cycles.

However, the presence of a cell wall is not one of their characteristics. Unlike organisms such as fungi and plants, which have rigid cell walls made of chitin and cellulose respectively, helminths are covered by a flexible cuticle. This cuticle serves several functions, including protection from the host's immune system, but it is not a cell wall in the traditional sense. Thus, the absence of a cell wall is the distinguishing factor in this context.