The Epidermis and Sense Organs of the Monogenea and Some Related Groups

Abstract

This chapter discusses the epidermis and sense organs of Monogenea and their larvae and also with the epidermis of some Turbellaria and Aspidogastrea. Although Turbellaria contains free-living forms but they are considered in the chapter because their epidermal fine structure with its function and development is considered to be related particularly to the free-living stages of the larvae of monogeneans. In addition, study of the turbellarians as a whole adds considerably to the knowledge of the range of epidermal structure open to the Platyhelminthes allowing the constancy of epidermal cytomorphology in various groups. It's possible use in taxonomy to be assessed and fostering a dawning appreciation of plasticity upon a basic structural plan in conformation to functional requirement. The Monogenea is a group with a fairly well worked out taxonomy that has been investigated in regard to epidermal fine structure so that the cytoarchitecture of this layer is now known in most of the major groups. Regarding sense organs and nervous systems: the ranges of neurotransmitter types and neurosecretory material need more detailed characterization and the function of neurosecretory products linked with the biology of these worms. More accurate methods for mapping sense organs on marine adult and larval worms, perhaps utilizing specific staining of nerve endings and stereoscan investigations involving critical point drying to preserve ciliary endings, are called for. The electrophysiological response of accessible sense organs (e.g. the haptor papillae of entobdellids) also needs to be studied. In all cases these investigations should be closely related to the overall behavior and biology of the stage under consideration.