Morphology and Electrophysiology of the Through-Conducting Systems in Pennatulid Coelenterates
Recent electrophysiological investigations of colonial anthozoan nervous systems (Anderson and Case, 1975; Shelton, 1975) have supplemented behavioral studies which found that colonial control was either through-conducted (Parker, 1920; Nicol, 1955; Horridge, 1957; Buck, 1973), or restricted to a finite portion of the colony with subsequent incremental spread (Horridge, 1957). In the Pennatulacea, colonial nervous systems have been found to be through-conducting (Anderson and Case, 1975; Shelton, 1975). A possible morphological basis for such coordination, namely ectodermal, mesogleal, and endodermal nerve nets, has been described within the rachis of some pennatulids (Titschack, 1968, 1970; Buisson, 1970). However, there is no conclusive evidence to link these nerve nets with through-conducted colonial coordination, and the exact morphological circuitry has yet to be elucidated. Here we correlate the morphology of possible conducting elements with the colonial behavior and the electrophysiology of the through-conducting systems of five species of pennatulids as a contribution towards determination of the anatomical basis for through-conduction.
KeywordsNerve Cell Conduction Velocity Longitudinal Muscle Water Canal Nerve Bundle
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