The negative effect of monogenea on piscine host may vary in the host species. Genus Mizelleus (Monogenea: Ancyrocephalidae) was reported for the first time from the freshwater shark, Wallago attu (Bl. and Schn.) at Lucknow by Jain (1957). Haptor or opisthohaptor of monogenea which is more or less discoid muscular structure situated posteriorly, is the chief adhesive organ. It is usually provided with anchors and marginal hooklets. Anchors, ventral transverse bar, together with the additional supporting dorsal bars (patches) are active elements of haptor while, marginal hooklets serve as secondary supportive participants, whereas, the dorsal transverse bar can be treated as an inactive element in the whole organ of attachment. Functional dynamics detail of haptoral armature is almost unattended. The anchors in case of M. indicus (Jain 1957) Pandey et al. (2003) are disposed one against the other and used to act like four lobed grapnel like a spreader. All components of haptoral armature contribute in one way or another in the process of functional process. Interestingly the worms do not follow the same pattern of sequences during their movements. Various elements and factors are involved in the process. The authors tried to pinpoint the changes in the activity of one major element i.e., dorsal anchor. The movement and change in position/orientation of various elements with reference to dorsal anchors were observed and summarized. Present paper is rare effort in unexplored aspect in monogenea biology.
Keywords: Adduction and abduction; Functional morphology; Haptor; Monogenean.