HYDROPHOBIC CAPACITY OF FEATHER ELEMENTS IN PENGUINS (AVES, SPHENISCIFORMES)

Specific differences in wettability of some feather elements (barbs an d barbulas) are absent in penguins. Barbs are moistened better than ba rbules in all feather categories. Fat extraction does not affect wetti ng of plumage elements for all feather categories. At the same time th ere are differences in wettability between the respective elements of surface and inner plumage layers. The latter is moistened better. The top-most layer of the plumage is best moistened due to it is composed of closely packed barbs of contour feathers without barbules (average contact angle is 60 degrees). Contour feather barbs are moistened and stick together resulting in formation of a tiled cover. Capillary forc es draw water into the interbarb gaps thereby plugging the gaps and pr eventing from air coming out of the deeper plumage layers. A similar e ffect has been described earlier for the North Sea seal Callorhinus ur sinus (Romanenko, Sokolov, 1987). The mechanisms, which maintain the a ir layer when diving, are also similar for these two animal groups tha t are not closely related taxonomically.