ROLE OF EPIDERMAL CILIA IN DEVELOPMENT OF THE AUSTRALIAN LUNGFISH, NEOCERATODUS-FORSTERI (OSTEICHTHYES, DIPNOI)

In common with the embryos of other anamniotes, young of the Australia n lungfish, Neoceratodus forsteri, have ciliated cells in the epidermi s. These first appear at stage 28, similar to 10 days before hatching, and develop progressively to a peak in numbers and in activity at sta ge 44, just after hatching. After this point, ciliary action in the ep idermal cells slowly declines, and cilia disappear completely from the outer surface of the hatchling by stage 52. Cilia are lost earlier fr om the oral epithelium, between stages 45 and 46, and from the epithel ium covering the gills and lining the operculum at stage 51, although they are retained in the nares and in the cavity of the olfactory orga n.To assess possible functions for the ciliated epidermis in lungfish hatchlings, the presence of cilia in the epidermis of young N. forster i is compared with landmarks of development. The ciliated epidermal ce lls are not associated with movements of the embryo within the egg cap sule, nor are they a part of a feeding mechanism. They are not related to oxygen uptake. The ciliated epidermis appears to function as a mec hanism for clearing the animal of particles and settling organisms bef ore hatching, when the egg membranes have developed holes, and after h atching, when the young fish is living among the submerged rootlets of trees growing on the river bank or in dense stands of aquatic plants. The function of a ciliated epidermis in N. forsteri hatchlings in rel ation to microhabitat is discussed. (C) 1996 Wiley-Liss, Inc.