Adaptive Modifications in Paired Fin Epidermis of the Hill-Stream Fish Homaloptera brucei of Kumaun Himalaya: A SEM Investigation

Surface architecture of paired fins of Homaloptera brucei, adapted to life in fast flowing streams, was examined in this study. The epidermis is differentiated into smooth and rough in both the fins. Rough epidermis covering the ventral surface is composed of mainly epithelial cells that are thrown into elongated curved- spine unculi in the pectoral fin and stout and blunt unculi in the pelvic fin. The smooth epidermis covering the remaining parts of the fins is equipped with the epithelial and the mucous cells secreting mucus, which cause a weak adhesion and prepare the substratum for subsequent action of the unculi. A dense network of microridges in the epithelial cells could be interpreted as a means to retain more and more mucus on the surface of epithelial cell.