Neurobiology of Parasitic Flatworms: How Much "Neuro" in the Biology?

The nervous systems in the parasitic Platyhelminthes have generally been considered to be degenerate and of marginal significance, but recent studies have shown these systems to be more significant in the biology of these animals than formerly believed. There are many similarities in the construction and apparent neurochemistry of the nervous systems in the parasitic forms as well as in the free-living Turbellaria. In all forms there appears to be a large neurohormonal component. Though the nervous system appears to be important for many aspects of parasitic flatworm biology, little direct or specific information about the physiology of these systems is yet available.